Дэлгэрэнгүй мэдээлэл

In this work, the transition metal copper (Cu) doped Zn1-xCuxO nanoparticles were synthesized by different doping concentration of Cu (x=1, 3, 5 and 7 M%) through surfactant free benzyl alcohol route method in which zinc acetate and copper acetate were selected as precursors. We have carried out the spin polarized density functional calculations based on the plane wave (PW) and projector augmented wave (PAW) methods using the generalized gradient approximation (GGA) by Perdew and Wang (PBE), as implemented in the QUANTUM ESPRESSO package within the framework of density functional theory (DFT). The following electronic states are treated, as valence electrons of Cu(3d104s1), Zn(3d104s2) and O(2s22p4) for atoms. The wave functions and charge densities are expressed as plane waves up to a kinetic energy cutoff of 60 and 300 Ry, respectively. We have done calculations on the hexagonal wurtzite ZnO unit cell and ZnO (3×3×2) supercell including the 36 Zn and 36 O atoms. For the Cu-doped ZnO nanoparticles 2 coppers are placed in the crystal structure at 3 different distances: short, medium, and long. We used the tetrahedral method when we evaluate the electronic total and projected density of state (DOS). For the self-consistent field (SCF) iterations, the total energy convergence is 10- 5 eV. The occupation numbers of electrons are expressed Gaussian distribution function with an electronic temperature of kT = 0.02 Ry. To express the strong correlated effect of electrons in the Cu(3d) and Zn(3d) states, we have chosen to be U = 3.5 and 8.5 eV respectively, using the simplified rotational-invariant formulation based on the linear response method. The numerical error in the magnetic energy gain was 3 meV. The ionic positions are relaxed at the fixed lattice parameters until the residual forces are less than 0.05eV/Å. An experimental result was validated theoretically by performing DFT calculations. Our predicted values of lattice parameters were agreed with our experimental values of crystal structure, in which the errors of the lattice parameter a are 1.14% and 1.01% by the PW and PAW methods, respectively. Our results of magnetism are shown that the hole-mediated ferromagnetism of Cu-doped ZnO is created by the double exchange mechanism, as created localized empty holes on the localized t2g state of Cu ions due to the bound magnetic polarons. These results agree with our experimental results

Amorphous molybdenum disulfide has shown potential as a hydrogen evolution catalyst, but the origin of its high activity is unclear, as its atomic structure. Here, we have developed a classical inter-atomic potential using the charge equilibration neural network method, and we have employed it to generate atomic models of amorphous MoS2 by melting and quenching processes. The amorphous phase contains an abundance of molybdenum and sulphur atoms in low coordination. Beside the 6-coordinated molybdenum typical of the crystalline phases, a substantial fraction displays coordinations 4 and 5. The amorphous phase is also characterized by the appearance of direct S-S bonds. Density functional theory shows that the amorphous phase is metallic, with a considerable contribution of the 4-coordinated molybdenum to the density of states at the Fermi level. S-S bonds are related to reduction of sulphur, with the excess electrons spread over several molybdenum atoms. Moreover, S-S bond formation is associated with a distinctive broadening of the 3s states which could be exploited for experimental characterization of the amorphous phases. The large variety of local environments, and the high density of electronic states at the Fermi level may play a positive role in increasing the electrocatalytic activity of this compound.

This paper presents an efficient and accurate method for solving the time-dependent Hartree-Fock equations for the helium atom in the ground state and single excited states. Instead of the usual finite difference method, the radial coordinate is discretized by the discrete variable representation (DVR), which constructed from Coulomb wave functions. The Coulomb wave function discrete variable representation (CWDVR) method uses many times fewer grid points than other numerical calculations. The resulting grid points of CWDVR are unevenly distributed, so that if 𝑘 is selected, one has a finer grid near the origin and coarser grid at greater distances, or in case of dispute, if 𝑍 parameters are selected, one has a finer grid at greater distance and a coarser grid at the origin.

Ferrites are the unique magnetic materials which that exhibit electrical as well as magnetic properties and hence are commercially and significantly important magnetic material. The types, quantities, and placements of the metal cations in the crystalline structure have a significant impact on the physicochemical properties of ferrites. Due to their unique and remarkable properties, nanocrystalline magnetic materials have attracted attention from various fields, such as physics, chemistry, biology, medicine, materials science, and engineering. Ferrites based on crystal structure and compositions, are classified, as spinel, garnet and hexaferrite. A brief investigation to various structures of ferrites materials such as Nickel (Ni) substituted Magnesium ferrite (Mg1-xNixFe2O4), Bismuth (Bi) substituted Barium hexaferrite (BaFe12-xBixO19) and 4d, 5d elements substituted iron phosphide compound (Fe2P) are explained herein. Using the first-principles method within framework of density functional theory (DFT) as implemented in the VASP, OpenMX and Vampire packages, we have performed the calculations by the ab initio pseudopotential projected augmented wave method with the Generalized Gradient Approximation (GGA). The Brillouin zone was integrated to different k-point sets generated by the Monkhorst-Pack method centered at the 5x5x5 (spinel) and 5x5x9 (hexagonal) points with optimized the energy cutoff of 500eV. Fig. 1 shows, our structures of spinel (Mg1-xNixFe2O4), hexagonal (BaFe12-xBixO19) and hexagonal (Fe2P) soft and hard magnetic materials.

Хүчтэй соронзон шинж чанар бүхий SmFe12(ThMn12) нэгдлийн тогтвортой бүтцийг туршилтын аргаар гарган авах нь бэрхшээлтэй байдаг. Бүтцийн тогтворжилтыг хольц элементүүдийн тусламжтайгаар, ялангуяа Ti-ийн атомаар хольцолж сайжруулдаг байна. Ti-ийг хольцолж өгсөнөөр фазын тогтворжилтыг сайжруулж нэгэн төрлийн кристалл бүтэц гарган авах боломжтой боловч системийн нийт соронзон шинж чанарт сөргөөр нөлөөлдөг. Энэхүү ажилд бид соронзон шинж чанарыг сайжруулах зорилгоор Ti атом хольцолсон SmFe12 нэгдэл дахь Fe-ийн атомуудыг тодорхой концентрациар Co атомуудаар давхар хольцлон соронзон шинж чанарын өөрчлөлтийг нягтын функциональ онолын (НФО) арга ашиглан гүйцэтгэв. Онолын судалгааны үр дүнгээс ThMn12 бүтэц бүхий SmFe11.5Ti0.5 нэгдлийн Co-ийн агууламжаас хамааруулан нийт соронзон, ханасан соронзон (Ms) болон соронзон анизотропын утгуудыг тодорхойлов. Co атом хольцлоход соронзон анизотроп болон соронзон моментыг өсгөх боломжтойг онолын тооцооллын үр дүн харуулж байна.

Төмрийн фосфид (Fe2P) нэгдэл нь гексагональ бүтэцтэй бөгөөд соронзон шинж чанар бүхий байдлаараа сүүлийн 50 жил судлаачдын сонирхолыг татаж байна[1]. Техник технологийн хувьд соронзон анизотроп их байдаг тул тогтмол соронзон (permanent magnet) материалд хэрэглэх боломжтой гэж үздэг. Гэвч ферромагнетик төлөвөөс фарамагнетик төлөвт шилжих Кюри температур нь туршилагаар 214K байдаг нь энэ материалын сул тал юм. Иймд энэ судалгааны зорилго нь Fe2P нэгдлийн Fe-ийн байршилд шилжилтийн 3d элементүүдээр хольцолж материалын нийт соронзжилт, корцетив хүчийг өсгөхийн тулд соронзон анизотроп энергийг өсгөх онолын судалгааг нягтын функциональ онолын (НФО) аргад суурилсан VASP програм хэрэглэн гүйцэтгэв. Мөн Кюрийн температурыг өсгөхийн тулд фосфорын байранд Si-ийн атом суулган тооцооцохдоо Монте Карло аргад суурилсан OPENMX, TB2J болон VAMPIRE програм ашиглан тооцоолол хийв. Онолын судалгааны үр дүнгээс химийн үелэх системийн Mn болон Si элементээр Fe2-xMnxP1-ySiy нэгдлийг зэрэг хольцлон нийт соронзжилт, корцетив хүч, Кюрийн температурыг өсгөх боломжтойг онолын судалгаагаар харууллаа.

Herein the pure LiYF4 and rare-earth-doped M-LiYF4 (M =Pr and Nd) compounds are synthesized by environmentally friendly and solid-state reaction methods. We have calculated the structure and electronic structure of these materials by the first-principles techniques using the PAW and PW methods with the Generalized Gradient Approximation (GGA-PBE), which are implemented on the Quantum Espresso package within the framework of Density Functional Theory (DFT). The optical properties of pure and rearearth-doped LiYF4 compounds were investigated by comparing theoretical and experimental methods. The outcomes of XRD, optical absorption, and emission measurements show that the doped samples are successfully synthesized. Our results of the optical properties of the Pr and Nd-doped LiYF4 compounds are demonstrated. The optical absorption and emission results of Pr-doped LiYF4 compounds obtain that this material can emit radiation with several wavelengths in visible ranges.

The self-consistent Hartree-Fock (HF) equations for helium atom are solved using the Coulomb Wave Function Discrete Variable Representation (CWDVR) approach. In this work, the atomic structure of the helium atom is determined by solving HF equations approximated by a Slater determinant. The self-consistent HF equations for ortho and para Helium atoms are solved the Coulomb Wave Function Discrete Variable approach. The exchange term is often approximated as an inhomogeneous or an effective potential so that the HF equations become a set of ordinary differential equations (which can be solved using the usual shooting methods). The discrete variable method is used for the uniform and optimal spatial grid discretization and solution of the HF equation. We illustrate that the calculated electronic energies for the helium atom are in good agreement with other best available values.

Ferrites are the unique magnetic materials which that exhibit electrical as well as magnetic properties and hence are commercially and significantly important magnetic material. The types, quantities, and placements of the metal cations in the crystalline structure have a significant impact on the physicochemical properties of ferrites [1]. Due to their unique and remarkable properties, nanocrystalline magnetic materials have attracted attention from various fields, such as physics, chemistry, biology, medicine, materials science, and engineering. Ferrites based on crystal structure and compositions, are classified, as spinel, garnet and hexaferrite. A brief investigation to various structures of ferrites materials such as Nickel (Ni) substituted Magnesium ferrite (Mg1-xNixFe2O4), Bismuth (Bi) substituted Barium hexaferrite (BaFe12-xBixO19) and 4d, 5d elements substituted iron phosphide compound (Fe2P) are explained herein. Using the first-principles method within framework of density functional theory (DFT) as implemented in the VASP, OpenMX and Vampire packages, we have performed the calculations by the ab initio pseudopotential projected augmented wave method with the Generalized Gradient Approximation (GGA). The Brillouin zone was integrated to different k-point sets generated by the Monkhorst-Pack method centered at the 5x5x5 (spinel) and 5x5x9 (hexagonal) points with optimized the energy cutoff of 500eV. Fig.1 shows, our structures of spinel (Mg1-xNixFe2O4), hexagonal (BaFe12-xBixO19) and hexagonal (Fe2P) soft and hard magnetic materials.

Herein the pure LiYF4 and rare-earth-doped M-LiYF4 (M =Pr and Nd) compounds are synthesized by environmentally friendly and solid-state reaction methods. We have calculated the structure and electronic structure of these materials by the first-principles techniques using the PAW and PW methods with the Generalized Gradient Approximation (GGA-PBE) implemented the Quantum Espresso package within the framework of Density Functional Theory (DFT). The optical properties of pure and rear-earth-doped LiYF4 compounds were investigated by comparing theoretical and experimental methods. The outcomes of XRD, optical absorption, and emission measurements show that the doped samples are successfully synthesized. Our results of the optical properties of the Pr and Nddoped LiYF4 compounds are demonstrated. The optical absorption and emission results of Pr-doped LiYF4 compounds obtain that this material can emit radiation with several wavelengths in visible ranges.

Herein we have explored the structural and electronic properties of pure and G/Li4Ti5O12 (LTO) compounds using the first-principles method based on the density functional theory, as an anode material for lithium-ion batteries. We have shown that the LTO material exhibits insulating behavior with the bandgap of 2.94 and 3.6 eV using the GGA and GGA+U calculations respectively. The diffusion pathways are optimized and the energy barriers of lithium migration are calculated with the climbing nudged elastic band method (CI-NEB). Results show that lithium diffusion in the charged state energy barrier is 0.24 eV respectively. In addition, We investigated the interfacial electronic structure, charge transfer properties, and Formation energy of graphene physisorption and chemisorption on the LTO(111) surfaces (Oxygen, Lithium, Titanium, and Lithium Titanium combined surfaces) from calculations. Calculations presented interface G/LTO(111)O chemisorption other interfaces G/LTO(111)Li, G/LTO(111)Ti,Li physisorption properties. Hence, The calculations show that a slight charge transfer occurs in the physisorption case while a significant charge transfer takes place in the chemisorption configuration. The most stable structures for calculating formation energy were surfaces with G/LTO(111)Li, G/LTO(111)O аnd G/LTO(111)Ti, Li.

Using first-principles density functional theory calculations we investigate the effect of a nickel substitution on the structural, electronic, and magnetic properties of magnesium ferrite Mg1−xNixFe2O4 (x = 0, 0.4, and 1). The calculated lattice constant (8.38 Å) and magnetic moment (3.57 μB) of Fe atom are in reasonable agreement with the present experimental values from the present neutron scattering measurements. The presence of Ni is found to decrease the electronic band gap and eventually leads to a metallic character at x = 1. Moreover, based on the Maxwell–Boltzmann statistical analyses, we have predicted that Mg1−xNixFe2O4 phases can have mixed spin configurations in a real sample, which in turn determines the measured magnetic properties.

Herein, we have predicted the electronic and magnetic properties and magnetocrystalline anisotropy (MCA) of the most stabilized antiferromagnetic (AFM) ground state of bulk chalcopyrite (CuFeS2) and films with various different thicknesses. We have shown that the easy axis of the bulk structure is along the [001] direction and it agrees with the results of neutron measurements. For the CuFeS2 film, our results have indicated that the ground state of ultra-thin film is ferromagnetic (FM) and the easy axis of ultra-thin film is in-plane. As the thickness of the film increases, its ground state becomes the AFM, and the easy axis is changed as an out-plane. It may be a natural candidate material for integrating spintronics.

We have presented the results of detailed studies of oxygen vacancy and niobium (Nb) substituted spinel Li4Ti5O12 (LTO) materials using the first-principles method within the framework of the density functional theory (DFT). We have shown that the ground state of oxygen vacancy and Nb-substituted LTO is paramagnetic (PM), and the Nb substitution is most stable on the 16d sites of both the Li and Ti ions. Our results indicate that the Nb substitution in the 16d site of Li-ion becomes the n-type metallic material. But the oxygen vacancy containing NbT i substituted LTO is changed from the p-type to the n-type, as increased concentration of Nb ions.

Энэхүү судалгааны ажлаар бид феррит соронзон нано бөөм болох Mg1−xNixFe2O4 (x=0.4, 0.6, 0.8) нэгдлийн инверсийн зэргээс хамаарч соронзон шинж чанар хэрхэн өөрчлөгдөх болон бүтцийн тогтворжилтын судалгааг квант механикийн нягтын функционалийн онол (НФО) ашиглан гүйцэтгэв. Тооцооллын үр дүнд системийн нийт соронзжилт инверсийн зэргээс хамаарч буурч байв. Харин бүтцийн хувьд Ni агууламжаас үл хамаарч инверсийн зэрэг δ = 0.9 байгаа тохиолдолд систем хамгийн тогтвортой байгааг тогтоолоо.

Herein, using first-principles density functional theory (DFT) calculations, we have investigated the effects of Bi substitution on the structural, electronic, and magnetic properties of barium hexaferrite (BaFe12-xBixO19, x = 0; 0.5; 1.5 and 2). As a result of the calculation, it was determined that the most stable structure exists if the spin of the Fe atom on the 2a, 2b, and 12k positions of the barium hexaferrite compound is taken in the upward direction. The calculated lattice constant ( c/a = 3.9) and magnetic moment (4.24 μB) of iron ions are in reasonable agreement with other experimental works. Moreover, the presence of bismuth reduces the electronic band gap. Energy gain and magnetic anisotropy energy calculations for FIM, FM, and NM states were performed for the most stable states. It has been established that the most stable structural state is characteristic of х = 0.5. It has been calculated that substitution by the large Bi3+ ion dramatically changed the electronic structure and sharply reduced the band gap. This paper is the first step towards establishing the nature of the distribution of ions in M-type hexaferrites under conditions of substitution by ions with a large ionic radius.

Copper-doped ZnO nanoparticles with a dopant concentration varying from 1–7 mol% were synthesized and their structural, magnetic, and photocatalytic properties were studied using XRD, TEM, SQUID magnetometry, EPR, UV-vis spectroscopy, and first-principles methods within the framework of density functional theory (DFT). Structural analysis indicated highly crystalline Cu-doped ZnO nanoparticles with a hexagonal wurtzite structure, irrespective of the dopant concentration. EDX and EPR studies indicated the incorporation of doped Cu2+ ions in the host ZnO lattice. The photocatalytic activities of the Cu-doped ZnO nanoparticles investigated through the degradation of methylene blue demonstrated an enhancement in photocatalytic activity as the degradation rate changed from 9.89 × 10−4 M min−1 to 4.98 × 10−2 M min−1. By the first-principles method, our results indicated that the Cu(3d) orbital was strongly hybridized with the O(2p) state below the valence band maximum (VBM) due to covalent bonding, and the ground states of the Cu-doped ZnO is favorable for the ferromagnetic state by the asymmetry of majority and minority states due to the presence of unpaired electron.

In this work, some properties of the InAs/InGaAs quantum well (QW) were calculated, such as the wave functions and the charge density of the 2D free electron gas (2DEG) by solving the Poisson- Schroedinger equation. The thinner capping layer gives charge densities forming inside the QW that are higher than the thicker values. The optimal thickness of the capping layer can be 10 nm due to the most stable charge density and fully symmetrical wave functions. Our result indicates that higher charge densities can be found with higher Si-delta doping concentrations. However, the distance of the Si-delta doping also affects the charge population. The charge density linearly decreases with a higher Si-delta doping spacer; the thickness was chosen as 7nm. We performed the growth with different concentrations of Si with optimal thicknesses and compared them with the calculated values. There is good agreement between the simulations and experiments with the lower Si-doping concentrations.

Бид энэхүү судалгааны ажлаар хүрээлэн буй орчинд ээлтэй горимоор, хатуу төлөвийн урвалын арга ашиглан LiYF4 болон газрын ховор элемент Pr3+ ионоор хольцлосон Pr:LiYF4 нэгдлүүд гарган авсан болон үзэгдэх гэрлийн мужид цацаргалт хийх Pr:LiYF4 нэгдлийн оптик шинж чанарыг судалсан үр дүнг танилцуулж байна. Рентген дифракц болон оптик шингээлтийн хэмжилтийн үр дүнгээс эдгээр ээжүүдийг амжилттай гарган авсан болох нь харагдаж байна. Pr:LiYF4-ийн оптик шингээлт болон цацаргалтын спектрийн хэмжилтээс энэхүү материал нь үзэгдэх гэрлийн янз бүрийн долгионы уртын мужид цацаргалт хийх боломжтой материал болохыг үзүүлэв.

МУИС-ийн Лазерын судалгааны төвийн судалгааны нэг чухал чиглэл нь лазерын материалын судалгаа юм. Лазер бодисын харилцан үйлчлэлийн судалгаанд судалж буй дээжийн шинж чанараас хамааруулан янз бүрийн долгионы урт бүхий лазераар өдөөн судлах шаардлага гардаг. Иймээс бид үзэгдэх гэрлийн мужид янз бүрийн долгионы урттай, илүү үр ашигтай лазерын ажиллагаа, гаралтын чадал бүхий цацаргалт хийх лазерын материалын судалгааг хийж байна. Энэхүү ажлаар нил улаан туяаны мужид цацаргалт хийдэг LiYF4 лазерын материалыг газрын ховор элемент Pr-аар хольцлон сайжруулж үзэгдэх гэрлийн мужид янз бүрийн долгионы урт бүхий лазерын цацаргалт хийх материал (Pr:LiYF4) гарган авах онолын тооцооны болон туршилтын судалгааны зарим үр дүнгээс танилцуулах болно.

The ferrite magnetic nanoparticles have been studied in many fields such as microwave devices, semiconductors, low magnetic materials, gas sensing, and hyperthermia therapy [1]. The hyperthermia therapy can be realized by the application of an AC magnetic field from external coils to cancer tumors using magnetic ferrite materials. Magnetite has been mainly investigated as the candidate material for this type of therapy [2-3]. In this study, we considered Nickel (Ni) substituted Magnesium ferrite Mg1-xNixFe2O4 (x=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) using the first-principles method within framework of density functional theory (DFT) as implemented in the VASP (Vienna Ab initio Simulation package). The calculations were performed by the pseudopotential planewave self-consistent field (PWscf) method with the Generalized Gradient Approximation (GGA). The Brillouin zone was integrated to different k-point sets generated with the Monkhorst-Pack method centered at the 5x5x5 point with optimized 500eV energy cutoff. The stability of the structure is calculated for the normal, the fully inverse, and partially inverse structure of pure MgFe2O4 Figure 1 shows, our created structure of ܰ݅Ni substituted MgFe2O4 in the partially inverse type. From the optimization, partially inverse was found most stable structure from all of the types. We have predicted the lattice parameter and magnetic moments from the spin-polarized calculation for ݃Mg1-xNixFe2O4 (x=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) compounds and compared them with neutron diffraction results. Neutron diffraction measurements were performed at HRFD JINR, Dubna [1]. References [1] W.B.K.Putri, E.A.Setiadi, V.Herika, A.P.Tetuko and P.Sebayang (2019). Natural iron sand-based Mg1-xNixFe2O4 nanoparticles as potential adsorbents for heavy metal removal synthesized by co-precipitation method. IOP Conf. Series: Earth and Environmental Science 277, 012031, 1755-1315. [2] B.Khongorzul, N.Tsogbadrakh and D.Sangaa (2017). Theoretical investigation of structure and magnetic property of cubic MgFe2O4. Mongolian Journal of Physics 25, ISSN 2311-1097, 50-54. [3] E.Uyanga, D.Sangaa, H.Hirazawa, N.Tsogbadrakh, N.Jargalan , I.A.Bobrikov , A.M.Balagurov (2018). Structural investigation of chemically synthesized Ferrite magnetic nanomaterials. Journal of Molecular Structure, 1160, 1 447-454. [4] D.Sangaa, B.Khongorzul, E.Uyanga, N.Jargalan, N.Tsogbadrakh, H.Hirazawa (2018). An overview of Investigation for Ferrite Magnetic Nanomaterials, Solid State Phenomena.

In this study, the adsorption of hazardous atoms including lead on the silica surface (SiO2 [001]) was investigated using the first-principles method within the framework of density functional theory (DFT). We performed the full structural optimization and found the most stable configuration. Four different sites were considered for the surface of silica, as well as four different sites for the surface of silica with an Al atom, and the adsorption energy along with the equilibrium geometry was determined. When the absorption energy was calculated at the four positions, the surface of silica and the surface of silica with Al had the same higher absorption at the first site (-6.66 eV and -9.11 eV). The value of the absorption energy indicates that a strong chemical bond has been formed between the lead and the surface. The maximum values for the absorption energy of the lead atoms were -6.93 eV for the silica surface and -9.11 eV for the silica surface with the Al atom. Furthermore, the structure added by aluminum with the ratio of 1:5 to build a similar structure of a zeolite crystal. Which provided more absorption energy. The value of the absorption energy indicates that a strong chemical bond has been formed between the lead and the surface. The density of state (DOS) is shown that the bandgap was 2.78 eV for the silica surface and 2.65 eV for the silica surface with Al atoms. The addition of the lead atom reduced the width of the bandgap due to the creation of a trapping layer within the bandgap.

We have calculated the energies of excited states for the He, Li, and Be atoms by the time dependent self-consistent Kohn Sham equation using the Coulomb Wave Function Discrete Variable Representation CWDVR) approach. The CWDVR approach was used the uniform and optimal spatial grid discretization to the solution of the Kohn-Sham equation for the excited states of atoms. Our results suggest that the CWDVR approach is an efficient and precise solutions of excited-state energies of atoms. We have shown that the calculated electronic energies of excited states for the He, Li, and Be atoms agree with the other researcher values.

We have investigated the magnetic properties of semiconducting molybdenum disulfide (MoS2) monolayer (ML) using the plane wave self-consistent field (PWscf) method within the framework of density functional theory (DFT). The pristine semiconducting bulk MoS2 is nonmagnetic (NM), due to the spin pairing of two electrons. We have indicated that the carriermediated ferromagnetism is available on the MoS2 ML as both the hole and electron carriers. The ordinary neutral S (VS0) vacancy creates the localized vacancy defect level and this level does not create the ferromagnetic (FM) state due to the spin pairing of two electrons by three Mo dangling bonds. While we have shown that the FM state is possible to create the FM state, due to the additional hole and electron carriers on the valency band and localized vacancy defect level by positively and negatively charged S (VS1+ and VS1- ) and positively charged Mo (VMo1+) vacancies.

Энэхүү ажилд литийн ионы батарейн анодын материал болох шпинел Li4Ti5O12 нэгдлийг цагаан тугалга (Sn) болон нүүрстөрөгчийн нано мяндас (carbon nanofiber) - аар хольцолж Li3.9Sn0.1Ti5O12, Li3.9Sn0.1Ti5O12/CNF нэгдлүүдийг золь гелийн аргаар гарган авч, дээжүүдийн бүтэц, шинж чанарыг онол болон туршлагын аргуудаар судалсан үр дүнг харуулав. Дээжийн кристалл бүтцийн шинж чанарыг судлахад рентген дифракцийн арга (XRD), нил улаан туяаны спектроскоп (FTIR)-ийн аргуудыг ашиглав. Онолын загварчлалын QUANTUM ESPRESSO багц програмаар Нягтын функционалийн онол дээр суурилсан ab initio квант механикийн аргыг ашиглан кристалл бүтэц ба электрон бүтцийн тооцооллыг гүйцэтгэлээ. Li3.9Sn0.1Ti5O12-ийн төлөвийн нягтыг тооцоолоход хориотой бүсийн өргөн цэвэр Li4Ti5O12-тай харьцуулахад харьцангуй бага буюу Eg=1.35 эВ байгааг харууллаа.

Энэхүү судалгааны ажилд литийн ионы батарейн анодын материалд ашиглах шпинел Li4Ti5O12 (LTO) нэгдлийг графенаар хольцлох үеийн электрон бүтцийг ab initio квант механикийн арга хэрэглэн судаллаа. Онолын загварчлалд шпинел LTO нэгдлийг дан үет графенаар хольцлосон атомын бүтцийг ашигласан бөгөөд Li4Ti5O12 нэгдлийн [100], [010] болон [001] кристаллографийн хавтгайнуудыг дан үет графенаар хольцлох үеийн электрон бүтцэд үүсэх нөлөөг судаллаа. LTO/Графен композит нэгдлийн тооцоог Нягтын функционалийн онол (НФО)-д суурилсан QUANTUM ESPRESSO багц програм ашиглан гүйцэтгэв. Тооцоонд тухайн байрлал дахь Кулоны түлхэлцлийн хүчний нөлөөг тооцох GGA+U-ийг ашиглан төлөвийн нягтыг тооцож, хориотой бүсийн өргөнийг онолоор тодорхойлов.

Transition-metal sulfides are an important class of Earth materials with a fascinating diversity of structure types that exhibit a host of technologically relevant electronic, magnetic, and catalytic properties. Because of the prominent role of sulfides as a source of nonferrous metals, the oxidation state of metals in these compounds has been extensively used in order to rationalize their fundamental crystal properties, the processes of mineral formation and breakdown, mineral processing, and their participation in environmental contamination associated with mining activities. However, it is surprising to find that, after numerous studies, there is still some debate on the assignation of oxidation states in a common mineral of prominent economic relevance such as chalcopyrite (CuFeS2) with a very high Neel temperature (TN = 823 K) , which represents the bulk of the world supplies of copper. Ternary chalcogenide compounds have recently attracted great attention due to their important physical and chemical properties and promising potential applications in solar power engineering and spintronics. The chalcopyrites compounds such as CuAlS2, CuInSe2, CuGaSe2, CuInS2 and CuFeS2 are typical representatives of the ternary chalcogenide family. They are semiconductors with a very broad band gap distribution from 3.5 to 0.6 eV. The CuFeS2 has the three phases, such as α - CuFeS2 tetragonal with a = 5.25 and c = 10.32 Å; β - CuFeS2 is cubic with a = 10.06 Å, and γ - CuFeS2 is tetragonal with a = 10.58 and c = 5.37 Å. The α-phase is antiferromagnetic, the β-phase is ferromagnetic and the γ-phase is non-magnetic behavior. In this study, we will consider the electronic structure, magnetism and magnetocrystalline anisotropy of α - CuFeS2 compound. Our calculations are based on the plane wave self - consistent field (PWscf) method using the generalized gradient approximation (GGA) by Perdew, Burke and Enzerhof (PBE) within the framework of spin polarized density functional theory (DFT), as implemented in the QUANTUM ESPRESSO package.

A density-functional approach for the calculation of singly, double excited states of atomic system have been calculated using a nonvariational, exchange potential within the nonrelativistic Hohenberg-Kohn-Sham density functional theory (DFT). The self-consistent Kohn-Sham equations for manyelectron atoms are solved using the Coulomb wave function Discrete Variable Method (CWDVR). The gradient-free representation functional is used to incorporate exchange functional. The discrete variable method is used for the uniform and optimal spatial grid discretization and solution of the Kohn-Sham equation. The equation is numerically solved using the CWDVR method. First time we have reported the solution of the Kohn-Sham equation on the excited state problem for the He, Li, Be atoms by the CWDVR method. Our results suggest that CWDVR approach shown to be an efficient and precise solution of excited state energies of atoms. We illustrate that the calculated electronic energies for corresponding atoms are in good agreement with other best available values. Estimating the energies and splitting of the 1s2s singlet and triplet states of atoms yields qualitatively correct results. Using a sixline computer program, the 1s2s energies calculated by matrix diagonalization using a seven-state basis improve the results to 0.4% error or better. A single-Slater-determinant energy of the electronic configuration is calculated by using these electron spin orbitals. Finally, a multiplet energy of an excited state is evaluated from the single-Slater-determinant energies of the electronic configurations involved in terms of Slater’s diagonal sum rule.

We investigated the effects of graphene doping on the structural and electronic properties of an anode material spinel Li4Ti5O12 for lithium ion batteries. Spinel structured Li4Ti5O12 has poor intrinsic electronic properties. In order to enhance it, a graphene was used, as additional composition. The Li4Ti5O12/graphene composites have been successfully synthesized by reduction process of graphene oxide via hydrothermal treatment. The morphology, crystal structure and elemental compositions of the prepared composites are characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-Ray diffraction (XRD), Fourier transform Infrared spectroscopy (FT-IR) and Thermogravimetric Analysis (TGA). The Li4Ti5O12/graphene composites exhibit a well-defined cubic spinel structure with an average particle size of approximately 400-500 nm. In the present study, in order to understand the effects of graphene coatings adsorbed on the surface of Li4Ti5O12, we have predicted by the first principles calculations based on the density functional theory (DFT).

Spinel Li4Ti5O12 (LTO) is one of the most promising candidate anode material for Li-ion battery (LIB) known, as zero strain material, it has poor intrinsic electronic properties. In order to enhance it, we have investigated effect of doping on electronic conductivity of spinel LTO phase structure. We consider the carrier and transition metal doping effect on structure and electronic structure of spinel LTO. It is shown that the doping can improve the electronic conduction of spinel LTO. Our calculations were based on the projector augmented wave (PAW) method with the generalized gradient approximation (GGA+U+J0) including the Hubbard U parameter for exchange correlation functional within the framework of density functional theory (DFT).

Herein, the spinel Co1-xZnxFe2O4 (x = 0, 0.2, 0.4 and 0.6) powder samples have been prepared by the solid-state reaction method. We have carried out the measurements of crystal structure, element analysis, material characterization, magnetic property and Curie temperature using the X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometer, and the first-principles calculations within the framework of the density functional theory (DFT). The EDS measurement indicates that the Co1-xZnxFe2O4 powder samples have been successfully synthesized and exhibited the cubic spinel structures. Both the lattice constant and crystallite size increase with the Zn concentration due to the larger ionic radius of Zn2+ ion than the Co2+ ion. The concentration ratio of the Co2+ and Co3+ ions can be predicted by the distribution of cations between the A and B sites by the XPS measurement. For the magnetic properties, the residual magnetization, coercivity and Curie temperature decrease monotonically as the Zn concentration increases, while the saturation magnetization initially increases and then decreases at the room temperature. For the Co0.8Zn0.2Fe2O4 sample, the magnetic saturation reaches the maximum value of 62.98 Am2kg-1, due to a large amount of the Co3+ ions. The adequate replacement of Zn ion for the Co site can improve the magnetic properties of spinel Co1-xZnxFe2O4 powders, and effectively regulates the Curie temperature.

New (1-x)Bi0.5Na0.5TiO3 + xCaFeO3-δ solid solution compounds were fabricated using a sol–gel method. The CaFeO3-δ materials were mixed into host Bi0.5Na0.5TiO3 materials to form a solid solution that exhibited similar crystal symmetry to those of Bi0.5Na0.5TiO3 phases. The random distribution of Ca and Fe cations in the Bi0.5Na0.5TiO3 crystals resulted in a distorted structure. The optical band gaps decreased from 3.11 eV for the pure Bi0.5Na0.5TiO3 samples to 2.34 eV for the 9 mol% CaFeO3-δ-modified Bi0.5Na0.5TiO3 samples. Moreover, the Bi0.5Na0.5TiO3 samples exhibited weak photoluminescence because of the intrinsic defects and suppressed photoluminescence with increasing CaFeO3-δ concentration. Experimental and theoretical studies via density functional theory calculations showed that pure Bi0.5Na0.5TiO3 exhibited intrinsic ferromagnetism, which is associated with the possible presence of Bi, Na, and Ti vacancies and Ti3+-defect states. Further studies showed that such an induced magnetism by intrinsic defects can also be enhanced effectively with CaFeO3-δ addition. This study provides a basis for understanding the role of secondary phase as a solid solution in Bi0.5Na0.5TiO3 to facilitate the development of lead-free ferroelectric materials.

Бид энэхүү ажлын хүрээнд нягтын функциональ арга ашиглан Y3Fe5O12 нэгдлийн онолын судалгааг гүйцэтгэллээ. Судалгааны ажлын үр дүнд температураас хамаарсан соронзон шинж чанар, статик соронзон орон дахь хувийн дулаан багтаамж болон Кюрийн температурын хамааралыг тооцооллоо.

In this study, the structure and electronic properties of the spinel compound Li4Ti5O12 (LTO) are investigated both theoretical and experimental methods. The experimental studies of structural and electronic properties were performed by X-ray diffraction and UV-visible spectroscopy. The first principles calculations allowed to establish the relationship between the structure and electronic properties. The spinel type structure of LTO is refined by the Rietveld analysis using the X-ray diffraction (XRD). The band gap of LTO was determined to be 3.55 eV using the UV-visible absorption spectra. The Density functional theory (DFT) augmented without and with the Hubbard U correction (GGA and GGA +U+J0) is used to elucidate the electronic structure of LTO. We have performed systematic studies of the first principles calculations based on the GGA and GGA+U for the crystal structure and electronic properties of spinel LTO. We propose that a Hubbard U correction improves the DFT results.

Herein, a metastable phase of β‐W type V3Ga is identified to exhibit an itinerant semiconducting antiferromagnetism. Density functional theory plus Hubbard U (DFT+U) calculations predict the β‐W type structure as a possible metastable phase, although energetically less favorable than the previously known D03 phase, which is successfully synthesized with good crystallinity by alternating evaporation method with postannealing process rather than traditional coevaporation method. Such a metastable β‐W phase results in an antiferromagnetic (AFM) order up to at least 500 K and highly conductive semiconducting behavior. The antiferromagnetism in the β‐W type V3Ga can be understood in terms of strong Coulomb repulsion and Hund's rule coupling between the nearest neighbor V 3d orbital states and their covalent bonding with the Ga 4p orbitals. These results are further verified by an exchange bias phenomenon revealed in antiferro/ferromagnet hybrid heterostructure of V3Ga and Fe films, where the strong hybridization between Fe 3d and V 3d orbital states at the interface gives rise to the robust perpendicular magnetic anisotropy therein. Herein, a novel route is used to prepare an AFM semiconductor material for antiferromagnet spintronics.

Нягтын функционалын онолын Кон-Шэмийн тэгшитгэлээр гелийн атомын нэг удаа өдөөгдсөн синглет, триплет төлөвүүдийн нягт ба энергийг тооцоолсон. Кон-Шэмийн тэгшитгэлийг бөмбөлөг координатын системд Кулоны долгион функцтэй дискрет хувьсагчийн аргаар бодсон. Энд координатыг жигд биш, оптималаар дискретчилж, нарийвчлал сайтай шийдийг гаргаж авч тооцоолсон. Тооцооны үр дүнгүүдийг Рой нарын псевдоспектриал аргаар тооцоолсон ба туршлагын үр дүнтэй харьцуулахад гелийн нэг удаа өдөөгдсөн синглет төлөвийн энергийн зөрүү нь 2.23%, гелийн нэг удаа өдөөгдсөн триплет төлөвийн энергийн зөрүү нь 2.20 % байна.

Нягтын функционалын онолын Кон-Шэмийн тэгшитгэлээр гелийн атомын нэг удаа өдөөгдсөн синглет, триплет төлөвүүдийн нягт ба энергийг тооцоолсон. Кон-Шэмийн тэгшитгэлийг бөмбөлөг координатын системд Кулоны долгион функцтэй дискрет хувьсагчийн аргаар бодсон. Энд координатыг жигд биш, оптималаар дискретчилж, нарийвчлал сайтай шийдийг гаргаж авч тооцоолсон. Тооцооны үр дүнгүүдийг Рой нарын псевдоспектриал аргаар тооцоолсон ба туршлагын үр дүнтэй харьцуулахад гелийн нэг удаа өдөөгдсөн синглет төлөвийн энергийн зөрүү нь 2.23%, гелийн нэг удаа өдөөгдсөн триплет төлөвийн энергийн зөрүү нь 2.20 % байна.

Current methods in theoretical solid-state physics, mainly facing a problem under the computational aspect, allow one to calculate the properties of materials by using techniques, which do not rely on input from experimental information. Such methods, based on quantum mechanics, are commonly denoted as first - principles or ab initio simulations. The first-principles simulation consists of two parts: Ab initio Ground state Total Energy calculations and Ab initio Thermodynamics calculations. These theoretical advances make it possible, to consider the electronic structure calculations and related other calculations, as a complementary tool to the experiment, which is in fact, completely independent from experimental inputs. Spintronics (meaning “spin transport electronics”) emerged from discoveries in the spin-dependent electron transport phenomena in solid-state devices. The next-generation spintronics devices make progress towards significant downscaling of the dimensions of devices, ultrafast read and write speed, and greatly reduced power consumption, which expects excellent spintronics materials possessing both high spin polarization (SP) and high spin injection (SI) efficiency simultaneously. We talk about the modern developments of electronic structure simulation and advanced energy magnetic materials with the applications of spintronics, such as diluted magnetic semiconductors, heusler alloys, and spinel ferrite, etc.

The self-consistent Kohn-Sham equations for many-electron atoms are solved using Discrete Variable Method. Wigner type functional is used to incorporate correlation functional. The discrete variable method is used for the uniform and optimal spatial grid discretization and solution of the Kohn-Sham equation. The equation is numerically solved using the CWDVR method. The results of the calculation for He, Li, Be, B, C, N, and O atoms are in good agreement with other best available values.

Spinel structured Li4Ti5O12 (LTO) is one of the most promising candidate anode material for Li-ion battery (LIB) known as zero strain material, it has poor intrinsic electronic properties. In order to enhance it, we have investigated the effect of doping on the electronic conductivity of the Li4Ti5O12 (LTO) cubic spinel phase structure. The electronic band structures of pristine LTO and doped LTO have been calculated using the first-principles method within the framework of density functional theory (DFT). It is shown that doping can improve the electronic conduction of LTO. In this study, we will consider the doping effect on the electronic structure of carrier and transition metal doped LTO spinel. Our calculations are based on the projector augmented wave (PAW) method using the generalized gradient approximation (GGA) within the framework of DFT.

Transition-metal sulfides are an important class of Earth materials with a fascinating diversity of structure types that exhibit a host of technologically relevant electronic, magnetic, and catalytic properties. Because of the prominent role of sulfides as a source of nonferrous metals, the oxidation state of metals in these compounds has been extensively used in order to rationalize their fundamental crystal properties, the processes of mineral formation and breakdown, mineral processing, and their participation in environmental contamination associated with mining activities. However, it is surprising to find that, after numerous studies, there is still some debate on the assignation of oxidation states in a common mineral of prominent economic relevance such as chalcopyrite (CuFeS2) with a very high Neel temperature (TN = 823 K) , which represents the bulk of the world supplies of copper. Ternary chalcogenide compounds have recently attracted great attention due to their important physical and chemical properties and promising potential applications in solar power engineering and spintronics. The chalcopyrites compounds such as CuAlS2, CuInSe2, CuGaSe2, CuInS2 and CuFeS2 are typical representatives of the ternary chalcogenide family. They are semiconductors with a very broad bandgap distribution from 3.5 to 0.6 eV. The CuFeS2 has the three phases, such as α - CuFeS2 tetragonal with a = 5.25 and c = 10.32 Å; β - CuFeS2 is cubic with a = 10.06 Å, and γ - CuFeS2 is tetragonal with a = 10.58 and c = 5.37 Å. The α-phase is antiferromagnetic, the β-phase is ferromagnetic and the γ-phase is non-magnetic behavior. In this study, we will consider the electronic structure, magnetism and magnetocrystalline anisotropy of α - CuFeS2 compound. Our calculations are based on the plane wave self - consistent field (PWscf) method using the generalized gradient approximation (GGA) by Perdew, Burke and Enzerhof (PBE) within the framework of spin-polarized density functional theory (DFT), as implemented in the QUANTUM ESPRESSO package.

A series of Mg1-xCaxFe2O4 ferrites was prepared by a solid-state reaction method. The crystal structure, the morphology and chemical composition, the magnetic properties of the ferrites were investigated by using XRD, SEM and VSM, respectively. The heating performance was measured in an alternating magnetic field (25 kHz). The results show that the ferrites form the single-phase cubic spinel structure in the Ca content x between 0 and 0.3, while a tetragonal phase forms at x=0.4. The lattice constants, the coercivity and the grain sizes increase with x, while the saturation magnetization changes nonlinearly. The saturation magnetization (Ms) reaches a maximum of 16.37 A·m2·kg-1 and the heating property is maximum at x = 0.1. It turns out that appropriate amounts of Ca substitution for Mg could improve the magnetic and heating performance of the ferrites, which have potential application and promising approaches for tumor therapy.

The self-consistent Kohn-Sham equations for many-electron atoms are solved using the Coulomb wave function Discrete Variable Method (CWDVR). Wigner type functional is used to incorporate correlation functional. The discrete variable method is used for the uniform and optimal spatial grid discretization and solution of the Kohn-Sham equation. The equation is numerically solved using the CWDVR method. First time we have reported the solution of the Kohn-Sham equation on the ground state problem for the many-electronic atoms by the CWDVR method. Our results suggest CWDVR approach shown to be an efficient and precise solution of ground-state energies of atoms. We illustrate that the calculated electronic energies for He, Li, Be, B, C, N and O atoms are in good agreement with other best available values.

The distribution of oxygen functional groups on the surface of graphene oxide (GO) has been investigated experimentally and theoretically. Atomic layer deposition of TiOx was used to clarify the location of oxygen functional groups. We found that the oxygen functional groups are distributed in the form of islands, which is confirmed using aberration corrected transmission electron microscopy and X-ray photoelectron spectroscopy. The density functional studies further support these findings. The evolution of oxygen functional groups was also investigated with GO treated at 150, 200, 250, and 300 0C. In addition, the reduction of epoxide and hydroxyl groups on the GO surface at different temperatures has been discussed in connection with ab initio molecular dynamics simulations.

Хувьсах соронзон оронд дулаан ялгаруулдаг шпинел бүтэцтэй феррит төрлийн соронзон нано материалыг хавдрын эсрэг халуун (hyperthermia) эмчилгээнд хэрэглэх зорилгоор судалж байна. Дулаан ялгаруулдаг шинж чанар нь материалын химийн найрлага, ионуудын тархалт, спины чиглэл болон бэлтгэх аргаас шууд хамаардаг. Хатуу төлвийн урвалын арга ашиглан гарган авсан (𝑀𝑔𝑥−1𝐶𝑢𝑥)𝐹𝑒2𝑂4 феррит нунтаг материалын хувьсах соронзон оронд дулаан ялгаруулдаг учир шалтгаан, механизм болон соронзон шинж чанарыг рентген дифракц, нейтрон дифракц, синхротрон цацрагийн сарнилын аргаар судлав. Соронзон материалын дулаан ялгаруулдаг механизмыг тайлбарлах үүднээс 𝑀𝑔𝐹𝑒2𝑂4, 𝐶𝑢𝐹𝑒2𝑂4, (𝑀𝑔𝑥−1𝐶𝑢𝑥)𝐹𝑒2𝑂4 болон 𝑀𝑔𝐹𝑒2𝑂4, 𝑀𝑔(𝐹𝑒𝑥𝐴𝑙2−𝑥)𝑂4 нэгдлүүдийн электрон, соронзон төлвийг квант механикийн тулгуур зарчмын онолоор тооцоолж бодсон үр дүнг тусгав.

Herein, we propose and provide evidence for the experimentally and theoretically promising route of exploring spintronics materials with high performance via a synthetic hybrid of half-metallic ferromagnet and diluted magnetic semiconductor. Crystalline and well-ordered [Co2FeGe/Ge(Mn)]n superlattice, which is free of secondary phase separation, were prepared by the hybridization of end members, Co2FeGe and Ge(Mn), using the molecular beam epitaxy technique. Besides comparable magnetic properties with respect to the Co2FeGe films, the superlattice sample exhibits superior properties in electric conductivity and spin polarization, thus enhancing in favor of the spin injection efficiency. These results demonstrate the high feasibility of spintronics materials with low saturation magnetization, small coercivity, high Curie temperature, and high spin injection efficiency through the proposed route in this work.

Cementite-type carbides are of interest for magnetocaloric applications owing to their temperature- or pressure-induced magnetic phase transition. Here, using first-principles calculations, we investigate the magnetism and the magnetic phase transition in iron carbide (Fe3C) with the substitution of Cr atoms at Fe sites with the strain effect. The presence of Cr atoms is found to give rise to a second-order magnetic phase transition from a ferromagnetic phase for Fe3C to a nonmagnetic phase in chromium carbide (Cr3C).While the ternary Fe2CrC and Cr2FeC compounds prefer the ferrimagnetic ground state, the magnitudes of both the Fe and Cr spin moments, which are antiparallel in orientation, decrease as x increases in Fe3−xCrxC (x = 0, 1, 2, and 3). Furthermore, the fixed spin-moment calculations indicate that the magnetization of Fe3−xCrxC compounds can be delicately altered via the strain effect and that the magnetic-nonmagnetic phase transition occurs at an early stage of Cr substitution, x = 2.

We have performed the study of electrochemical properties of the spinel Li4Ti5O12 anode materials in Li-ion batteries. The Li4Ti5O12 was successfully synthesized by a solid state reaction method at different temperatures according to the Li4Ti5O12 cubic spinel phase structure. The synthesized samples were characterized by X-ray diffraction (XRD). In this study, we used a first principle method, based on the density functional theory to explore electronic structure. We have shown that the Li4Ti5O12 anode material exhibits an insulating behavior with the band gap of 3.3 eV and the Li7Ti5O12 becomes metallic as Li atoms inserted in Li4Ti5O12 anode material.

Abstract The number of charge-discharge cycles in the lithium- iron- phosphate battery is limited by cathode degradation due to phase separation LiFePO4 → FePO4 + LiFePO4 .Same nature separation occurs spontaneously under ambient conditions in an optically transparent solid solution Na1-xAgxBr through formula Na1-xAgxBr → NaBr + AgBr. The mechanism of phase separation in Na1-xAgxBr can be used as a possible model of degradation of LiFePO4 cathode. In this paper, to study the phase separation in Na1-xAgxBr, a thin films of solid solutions at x = 0, 0.25, 0.50, 0.75, 1.0, were fabricated by rapid vacuum deposition (1-5 nm / s) of powder mixture on a glass or quartz substrates. Were also fabricated sandwiched films of the same thickness (100 nm), NaBr (t1) + AgBr (t2) where the thicknesses of layers t1 (t2) varied as 0 (100); 20 (80); 40 (60); 60 (40); 80 (20); 100 (0) nm. The absorption spectra of the films in a broad optical range of 200-900 nm, including the area of transparency of both layers and the absorption band of edge exciton of AgBr were measured with a daily interval. Morphological changes (granulation) in films were photographed through an optical microscope with 1000-fold magnification. The growth of the granules in a film were accompanied by transparency loss due to light scattering at the grains and widening of edge excitonic absorption band of AgBr. Annealing the films at 2000C before and after granulation slowed a growth of the granules, but did not lead to their disappearing. The work offers possible mechanism of granulation process in these films. Keywords: Thin films of a solid solution of Na1-xAgxBr, growth of granules, light scattering on a granules, excitonic absorption. Литература 1. Н.Тувжаргал, Б. Бат-Отгон, Ж. Даваасамбуу, Г. Еколд “ Изучение магнитных свойств и кинетики фазового разделения в LiхFePo4” Ученые записки Монгольского национального университета, серия “Физика” № 362 (17), стр. 108-110 (2012) 2. De Li, Haoshen Zhau “Two-phase transition of Li-intercalation compounds in Li-ion batteries” Materials Today, Volume 17, Issue 9, pages 451-463, November 2014. 3. This work has been done with financial support of the advanced research project of National University 4. of Mongolia on title: “Study of static displacement and phase transitions in solid solutions” (2016), 5. And the research project: “The investigation of heavy metal contamination of soil on Hanbogd and 6. Tsogttsetsii villages of Umnugobi province, where located OyuTolgoi and TavanTolgoi mines” (2015) 7. supported by the Asia Research Center, Mongolia and Korea Foundation for Advanced Studies, Korea. Acknowledgement This work has been done with financial support of the advanced research project of National University of Mongolia on title: “Study of static displacement and phase transitions in solid solutions” (2016), and the research project: “The investigation of heavy metal contamination of soil on Hanbogd and Tsogttsetsii villages of Umnugobi province, where located Oyu Tolgoi and Tavan Tolgoi mines” (2015) supported by the Asia Research Center, Mongolia and Korea Foundation for Advanced Studies, Korea.

Abstract The number of charge-discharge cycles in the lithium- iron- phosphate battery is limited by cathode degradation due to phase separation LiFePO4 → FePO4 + LiFePO4 .Same nature separation occurs spontaneously under ambient conditions in an optically transparent solid solution Na1-xAgxBr through formula Na1-xAgxBr → NaBr + AgBr. The mechanism of phase separation in Na1-xAgxBr can be used as a possible model of degradation of LiFePO4 cathode. In this paper, to study the phase separation in Na1-xAgxBr, a thin films of solid solutions at x = 0, 0.25, 0.50, 0.75, 1.0, were fabricated by rapid vacuum deposition (1-5 nm / s) of powder mixture on a glass or quartz substrates. Were also fabricated sandwiched films of the same thickness (100 nm), NaBr (t1) + AgBr (t2) where the thicknesses of layers t1 (t2) varied as 0 (100); 20 (80); 40 (60); 60 (40); 80 (20); 100 (0) nm. The absorption spectra of the films in a broad optical range of 200-900 nm, including the area of transparency of both layers and the absorption band of edge exciton of AgBr were measured with a daily interval. Morphological changes (granulation) in films were photographed through an optical microscope with 1000-fold magnification. The growth of the granules in a film were accompanied by transparency loss due to light scattering at the grains and widening of edge excitonic absorption band of AgBr. Annealing the films at 2000C before and after granulation slowed a growth of the granules, but did not lead to their disappearing. The work offers possible mechanism of granulation process in these films. Keywords: Thin films of a solid solution of Na1-xAgxBr, growth of granules, light scattering on a granules, excitonic absorption. Литература 1. Н.Тувжаргал, Б. Бат-Отгон, Ж. Даваасамбуу, Г. Еколд “ Изучение магнитных свойств и кинетики фазового разделения в LiхFePo4” Ученые записки Монгольского национального университета, серия “Физика” № 362 (17), стр. 108-110 (2012) 2. De Li, Haoshen Zhau “Two-phase transition of Li-intercalation compounds in Li-ion batteries” Materials Today, Volume 17, Issue 9, pages 451-463, November 2014. 3. This work has been done with financial support of the advanced research project of National University 4. of Mongolia on title: “Study of static displacement and phase transitions in solid solutions” (2016), 5. And the research project: “The investigation of heavy metal contamination of soil on Hanbogd and 6. Tsogttsetsii villages of Umnugobi province, where located OyuTolgoi and TavanTolgoi mines” (2015) 7. supported by the Asia Research Center, Mongolia and Korea Foundation for Advanced Studies, Korea. Acknowledgement This work has been done with financial support of the advanced research project of National University of Mongolia on title: “Study of static displacement and phase transitions in solid solutions” (2016), and the research project: “The investigation of heavy metal contamination of soil on Hanbogd and Tsogttsetsii villages of Umnugobi province, where located Oyu Tolgoi and Tavan Tolgoi mines” (2015) supported by the Asia Research Center, Mongolia and Korea Foundation for Advanced Studies, Korea.

Abstract Average copper recovery at the Erdenet Mining Corporation (EMC) is 86.5% and stable without any significant seasonal changes, while molybdenum recovery is lower (46%) and changes drastically during spring-summer season of each year. This molybdenum recovery volatility is the subject of this study. We suggest the bad and random molybdenum recovery is caused by seasonal changes of composition of dissolved salts, oxygen in circulating water that used for flotation enrichment at the EMC. The Central Research Laboratory (CRL) of the EML measures once at every month content of elements Cu, Fe, Ca, Mg, Mo and salt forming ions SO4 2- , HCO3 1- , CO3 2- and pH, hardness, dry residue in the circulating water. As shows our correlation analyses of CRL monthly data with weather data such as monthly average air temperature and moisture, wind speed, and precipitation during 2008-2011 years, content of dominant ions Ca2+, Mg2+ , SO4 2- , HCO3 1- and other ions in the circulating water changes seasonally: in summer-autumn season (July-to-October) content of dominant ions and dissolved oxygen, carbon dioxide changes rapidly in consistent with rainfall net amount and wind intensity; during winter time (November – to - March), when the artificial lake is mostly covered with ice, content of two dominant ions pair Ca2+ - SO4 2- is high and stable, simultaneously, content of dissolved oxygen falls 3-4 times to 2-3 ppm level. During March-April period, artificial lake ice cover melts and dilutes circulating water, decreasing the dry residue of the circulating water up to 15-20%. The end of May-to- end of June period is very special. During this relatively warm, dry, and windy time, the surface water of the artificial lake intensively evaporates and circulating water becomes thick as during winter peak time. At the same time, because of high intense dry winds, artificial lake enriches with dissolved oxygen and carbon dioxide gases. So the circulating water contains higher amount of dissolved oxygen and SO4 2- ions during the spring-to-summer period. Surface of molybdenite particles in the pulp media can be oxidized in two steps if a presence of dissolved oxygen and SO4 2- ions are simultaneous and sufficient. This two step surface oxidation increases hydrophilic property of the molybdenite particles in the pulp and consequently decreases their floatability and finally causes bad recovery of molybdenum at the EMC during the spring-to-summer period. Acknowledgement: This work has been done with financial support of the advanced research project of National University of Mongolia on title “Study of static displacement and phase transitions in solid solutions” (2016) and the research project: “The investigation of heavy metal contamination of soil on Hanbogd and Tsogttsetsii villages of Umnugobi province, where located Oyu Tolgoi and Tavan Tolgoi mines” (2015) supported by the Asia Research Center, Mongolia and Korea Foundation for Advanced Studies, Korea.

Molybdenum recovery efficiency seasonal instability at the Erdenet Mining Corporation Average copper recovery at the Erdenet Mining Corporation (EMC) is 86.5% and stable without any significant seasonal changes, while molybdenum recovery is lower (46%) and changes drastically during spring-summer season of each year. This molybdenum recovery volatility is the subject of this study. We suggest the bad and random molybdenum recovery is caused by seasonal changes of composition of dissolved salts, oxygen in circulating water that used for flotation enrichment at the EMC. The Central Research Laboratory (CRL) of the EML measures once at every month content of elements Cu, Fe, Ca, Mg, Mo and salt forming ions SO4 2-, HCO31-, CO32- and pH, hardness, dry residue in the circulating water. As shows our correlation analyses of CRL monthly data with weather data such as monthly average air temperature and moisture, wind speed, and precipitation during 2008-2011 years, content of dominant ions Ca2+, Mg2+ , SO4 2-, HCO31- and other ions in the circulating water changes seasonally: in summer-autumn season (July-to-October) content of dominant ions and dissolved oxygen, carbon dioxide changes rapidly in consistent with rainfall net amount and wind intensity; during winter time (November – to - March), when the artificial lake is mostly covered with ice, content of two dominant ions pair Ca2+ - SO4 2- is high and stable, simultaneously, content of dissolved oxygen falls 3-4 times to 2-3 ppm level. During March-April period, artificial lake ice cover melts and dilutes circulating water, decreasing the dry residue of the circulating water up to 15-20%. The end of May-to- end of June period is very special. During this relatively warm, dry, and windy time, the surface water of the artificial lake intensively evaporates and circulating water becomes thick as during winter peak time. At the same time, because of high intense dry winds, artificial lake enriches with dissolved oxygen and carbon dioxide gases. So the circulating water contains higher amount of dissolved oxygen and SO4 2- ions during the spring-to-summer period. Surface of molybdenite particles in the pulp media can be oxidized in two steps if a presence of dissolved oxygen and SO4 2- ions are simultaneous and sufficient. This two step surface oxidation increases hydrophilic property of the molybdenite particles in the pulp and consequently decreases their floatability and finally causes bad recovery of molybdenum at the EMC during the spring-to-summer period. Acknowledgement: This work has been done with financial support of the advanced research project of National University of Mongolia on title “Study of static displacement and phase transitions in solid solutions” (2016) and the research project: “The investigation of heavy metal contamination of soil on Hanbogd and Tsogttsetsii villages of Umnugobi province, where located Oyu Tolgoi and Tavan Tolgoi mines” (2015) supported by the Asia Research Center, Mongolia and Korea Foundation for Advanced Studies, Korea.

In recently, the CuFe2O4, MgFe2O4, MgAl2O4 and their mixed alloys, which are crystalline minerals composed of iron oxide in combination with some other metal, are becoming useful materials to the cancer tumor due to the heat generation ability [1, 2, 3]. The magnetic material such as fine ferrite powder having high heat generation ability in AC magnetic field was studied for application to thermal coagulation therapy of cancer tumor. The Mg1- XCuXFe2O4 type ferrite powders that have high heat generation ability in AC magnetic field were prepared by solid reaction method. The cubic type ferrite structure was obtained for x = 0 - 0.6 samples calcined at 1200oC, and the mixture phase of cubic and tetragonal structures were obtained for x = 0.7, 0.8 samples from XRD result [4]. The Al3+ substituted MgAlxFe2-xO4 ferrite was prepared by sol-gel method and MgAlxFe2-xO4 is better is prepared by a sol-gel method than a solid reaction method. From XRD results, the peak of the single phase of cubic crystal was obtained by calcined at 1200℃ [5]. The magnetic behaviour exhibited by the ferrites is called ferrimagnetism; it is quite different from the magnetization (called ferromagnetism) that is exhibited by metallic materials such as iron. In ferromagnetism there is only one kind of lattice site, and unpaired electron spins (the motions of electrons that cause a magnetic field) line up in one direction within a given domain. In ferrimagnetism, on the other hand, there is more than one kind of lattice site, and electron spins align so as to oppose one another — some being “spin-up” and some being “spin-down”— within a given domain. Incomplete cancellation of opposing spins leads to a net polarization, which, though somewhat weaker than for ferromagnetic materials, can be quite strong. Here we present the results of the magnetic property and their magnetic phase transition from the magnetic phase to the non magnetic phase in the MgAlxFe1-xO4 (x = 0, 1 and 2) alloys using the local spin density approximation (LSDA) by Perdew and Wang (PW91) [6] within the framework of DFT [7, 8], as implemented in the QUANTUM ESPRESSO package [9]. Our results are shown that the first – order magnetic phase transition occurs when the MgFe2O4 transfers to MgAl2O4 by the Al substitution doping. ACKNOWLEDGMENTS This work was supported by the project titled “Study of the Structure and Magnetic Property for Mixed Metal containing Compounds” for the Mongolian Foundation for Science and Technology in Mongolia. REFERENCES 1. T. MAEHARA, K. KONISHI, T. KAMIMORI, H. AONO, H. HIRAZAWA, T. NAOHARA, S. NOMURA, H. KIKKAWA, Y. WATANABE AND K. KAWACHI, J. Mater. Sci. 40, 135 (2005). 2. H. HIRAZAWA, H. AONO, T. NAOHARA, T. MAEHARA, M. SATO AND Y. WATANABE, J. Magn. Magn. Mater. 323, 675 (2011). 3. S. UTSUNOMIYA, H. HIRAZAWA, H. AONO, T. NAOHARA, T. MAEHARA AND Y. WATANBE, J. Magn. Soc. Jpn. 37, 291 (2013). 4. T. SHIRAISHI, H. HIRAZAWA, D.SANGAA, N.TSOGBADRAKH, AND H. AONO, “The Magnetic Properties for Mg1-xCuxFe2O4 Having High Heat Generation Ability in an AC Magnetic Field”, (poster presentation), The 2nd International Symposium on Frontier in Materials Science, 19 – 21 November, 2015, Waseda University, Tokyo, Japan 5. Y. ITO, H. HIRAZAWA, D.SANGAA, N. TSOGBADRAKH, AND H. AONO, “Heat Generation Ability in AC Magnetic Field of MgAlxFe2-xO4 Ferrite Powder Prepared by Sol-Gel Method”, (poster presentation), The 2nd International Symposium on Frontier in Materials Science, 19 – 21 November, 2015, Waseda University, Tokyo, Japan 6. J. P. PERDEW AND Y. WANG, Phys. Rev. B 45, 13244 (1992). 7. P. HOHENBERG AND W. KOHN, Phys. Rev. 136, B864 (1964). 8. W. KOHN AND L. J. SHAM, Phys. Rev. 140, A1133 (1965). 9. P. GIANMOZZI AND et al. J. Phys.: Condens. Matter 21, 395502 (2009).

In calculations of the crystal lattice dynamics and elastic constants is still popular equations of G.L.Squires1, which are expressed through the Born-von-Karman force constants. The equations of G.L.Squires are successfully used by W.M.Shyu and G.D.Gaspari2 for calculations of elastic constants of simple FCC and BCC metals within pseudopotential theory, but it was revealed that the theoretical values of Born-von-Karman force constants significantly differ from experimental values calculated from the fitting of experimental phonon spectra. The Born-von-Karman force constants are not so convenient to use in fitting procedures of phonon spectra, because it is necessary up to six types of force constants on depending on the atomic coordinates. The temperature dependent elastic constants are usually dominated by anharrmonic interactions and the full theoretical treatment is rather involved.3 Our calculations are based on the plane wave self-consistent field (PWscf) method using the generalized gradient approximation (GGA) by Perdew and Wang (PW91)4 within the framework of density functional theory (DFT),5-6 as implemented in the QUANTUM ESPRESSO package.7 The following electronic state is treated as valence: Fe(3s23p63d64s1) and Cr(3s23p63d54s1) for atoms. The interaction between the ions and valence electrons is expressed as the ultrasoft pseudopotential.8 The wave functions are expressed as plane waves up to a kinetic energy cutoff of 40 Ry. The summation of charge densities is done using the special k-points generated by the 14x14x14 Monkhorst-Pack meshes.9 We used the tetrahedral method10 when we evaluate the electronic density of state (DOS). For the self-consistent cycle the total energy convergence is 10-5 eV. The occupation numbers of electrons are expressed Gaussian distribution function with an electronic temperature of kT = 0.001 Ry. The atomic ionic positions are relaxed at the fixed lattice parameters until the residual forces are less than 0.05 eV/Å. In this presentation, we will present the results of the magnetic phase stability, and predictions of lattice parameter and temperature dependent elastic constants of pure bcc Fe (FM), mixed bcc Fe0.5Cr0.5 (FM) and pure bcc Cr (AFM) using the quantum mechanical simple method by Fuchs11 and semiemperical Varshni expression.12 We will also compare the current results with the previous methods.13-14

Al substituted MgAlXFe2-XO4 that have high heat generation ability in the AC magnetic field was obtained by Sol-Gel method. The heat generation ability was improved by Al3+ substitution, the highest heat generation property (ΔT=127.2oC) was confirmed for X=0.25 sample. This high heat generation ability was depended on hysteresis loss value, the hysteresis loss for X=0.25 samples were significantly increased in the AC magnetic field.