Using an effective field theory with correlations, magnetic properties of an octahedral chain described by a mixed spin Ising model are investigated. Unique phenomena such as multiple hysteresis loops, saturation magn...Using an effective field theory with correlations, magnetic properties of an octahedral chain described by a mixed spin Ising model are investigated. Unique phenomena such as multiple hysteresis loops, saturation magnetization, and reverse flip of the magnetization plateaus occur when certain typical parameters are applied. These results may be helpful to further investigate the magnetic properties of one-dimensional systems and could potentially be utilized in the design of spin devices.展开更多
The tremendous potential of triboelectric generators-TENGs for converting mechanical energy into electrical energy places them as one of the most promising energy harvesting technologies. In this work, the fabrication...The tremendous potential of triboelectric generators-TENGs for converting mechanical energy into electrical energy places them as one of the most promising energy harvesting technologies. In this work, the fabrication of enhanced performance TENGs using Ag octahedron nano-assemblies on ITO as electrodes significantly increases the electric charge collection of the induced tribocharges. Thereby, nanostructured electrical contacts coated with Ag macroscale nano-assemblies with octahedral features were obtained by the electrodeposition technique on flexible PET/ITO substrates. Consequently, the nanostructured triboelectric generator-TENG exhibited 65 times more maximum output power, and almost 10 times more open circuit output voltage than that of a TENG with non-nanostructured contacts passing from μW to m W capabilities, which was attributed to the increment of intrinsic interface states due to a higher effective contact area in the former. Likewise, output performances of TENGs also displayed an asymptotic behavior on the output voltage as the operating frequency of the mechanical oscillations increased, which is attributed to a decrement in the internal impedance of the device with frequency. Furthermore, it is shown that the resulting electrical output power can successfully drive low power consumption electronic devices. On that account, the present research establishes a promising platform which contributes in an original way to the development of the TENGs technology.展开更多
The structural, magnetic and electronic properties of the double perovskite Ba2SmNbO6 （for the simple cubic structure where no octahedral tilting exists anymore） are studied using the density functional theory withi...The structural, magnetic and electronic properties of the double perovskite Ba2SmNbO6 （for the simple cubic structure where no octahedral tilting exists anymore） are studied using the density functional theory within the generalized gradient approximation as well as taking into account the on-site Coulomb repulsive interaction. The total energy, the spin magnetic moment, the band structure and the density of states are calculated. The optimization of the lattice constants is 8.5173 A, which is in good agreement with the experimental value 8.5180 A. The calculations reveal that Ba2SmNbO6 has a stable ferromagnetic ground state and the spin magnetic moment per molecule is 5.00μB/f.u. which comes mostly from the Sin3＋ ion only. By analysis of the band structure, the compound exhibits the direct band gap material and half-metallic ferromagnetic nature with 100% spin-up polarization, which implies potential applications of this new lanthanide compound in magneto-electronic and spintronic devices.展开更多
The competition between dimensionality and ordering in multiferroic materials is of great interest for both fundamental physics and potential applications. Combining first-principles calculations with micromagnetic si...The competition between dimensionality and ordering in multiferroic materials is of great interest for both fundamental physics and potential applications. Combining first-principles calculations with micromagnetic simulations, we investigate recently synthesized ultrathin perovskite bismuth ferrite(BFO) films. Our numerical results reveal that, at the monolayer limit, the ferroelectricity of BFO is missing because the octahedral distortions are constrained. However, the monolayer bismuth ferrite is a topological antiferromagnetic metal with tunable bimeron magnetic structure. The dual topologically non-trivial characteristics make monolayer bismuth ferrite a multifunctional building block in future spintronic devices.展开更多
The biggest challenging issue in photocatalysis is efficient separation of the photoinduced carriers and the aggregation of photoexcited electrons on photocatalyst’s surface.In this paper,we report that double metall...The biggest challenging issue in photocatalysis is efficient separation of the photoinduced carriers and the aggregation of photoexcited electrons on photocatalyst’s surface.In this paper,we report that double metallic co-catalysts Ti3C2 MXene and metallic octahedral(1T)phase tungsten disulfide(WS2)act pathways transferring photoexcited electrons in assisting the photocatalytic H2 evolution.TiO2 nanosheets were in situ grown on highly conductive Ti3C2 MXenes and 1T-WS2 nanoparticles were then uniformly distributed on TiO2@Ti3C2 composite.Thus,a distinctive 1T-WS2@TiO2@Ti3C2 composite with double metallic co-catalysts was achieved,and the content of 1T phase reaches 73%.The photocatalytic H2 evolution performance of 1T-WS2@TiO2@Ti3C2 composite with an optimized 15 wt%WS2 ratio is nearly 50 times higher than that of TiO2 nanosheets because of conductive Ti3C2 MXene and 1T-WS2 resulting in the increase of electron transfer efficiency.Besides,the 1T-WS2 on the surface of TiO2@Ti3C2 composite enhances the Brunauer–Emmett–Teller surface area and boosts the density of active site.展开更多
Lattice,charge,orbital,and spin are the four fundamental degrees of freedom in condensed matter,of which the interactive coupling derives tremendous novel physical phenomena,such as high-temperature superconductivity...Lattice,charge,orbital,and spin are the four fundamental degrees of freedom in condensed matter,of which the interactive coupling derives tremendous novel physical phenomena,such as high-temperature superconductivity（high-T_c SC） and colossal magnetoresistance（CMR） in strongly correlated electronic system.Direct experimental observation of these freedoms is essential to understanding the structure-property relationship and the physics behind it,and also indispensable for designing new materials and devices.Scanning transmission electron microscopy（STEM） integrating multiple techniques of structure imaging and spectrum analysis,is a comprehensive platform for providing structural,chemical and electronic information of materials with a high spatial resolution.Benefiting from the development of aberration correctors,STEM has taken a big breakthrough towards sub-angstrom resolution in last decade and always steps forward to improve the capability of material characterization;many improvements have been achieved in recent years,thereby giving an indepth insight into material research.Here,we present a brief review of the recent advances of STEM by some representative examples of perovskite transition metal oxides;atomic-scale mapping of ferroelectric polarization,octahedral distortions and rotations,valence state,coordination and spin ordering are presented.We expect that this brief introduction about the current capability of STEM could facilitate the understanding of the relationship between functional properties and these fundamental degrees of freedom in complex oxides.展开更多
The interfacial enhanced ferromagnetism in maganite/ruthenate system is regarded as a promising path to broaden the potential of oxide-based electronic device applications.Here,we systematically studied the physical p...The interfacial enhanced ferromagnetism in maganite/ruthenate system is regarded as a promising path to broaden the potential of oxide-based electronic device applications.Here,we systematically studied the physical properties of La_(1-x)Ca_(x)MnO_(3)/SrRuO_(3)superlattices and compared them with the La1-x Cax MnO_(3)thin films and bulk compounds.The La_(1-x)Ca_(x)MnO_(3)/SrRuO_(3)superlattices exhibit significant enhancement of Curie temperature(TC)beyond the corresponding thin films and bulks.Based on these results,we constructed an extended phase diagram of La_(1-x)Ca_(x)MnO_(3)under interfacial engineering.We considered the interfacial charge transfer and structural proximity effects as the origin of the interfaceinduced high TC.The structural characterizations revealed a pronounced increase of B-O-B bond angle,which could be the main driving force for the high TCin the superlattices.Our work inspires a deeper understanding of the collective effects of interfacial charge transfer and structural proximity on the physical properties of oxide heterostructures.展开更多
The spin-orbit interaction of the 5d electron needs to be taken into account to give the proper energy structure for the 4fN-1 5d configuration of heavy lanthanide ions occupying a site with ligands forming an octahed...The spin-orbit interaction of the 5d electron needs to be taken into account to give the proper energy structure for the 4fN-1 5d configuration of heavy lanthanide ions occupying a site with ligands forming an octahedron. This paper derives theoretical results for the energy structure by treating the t2 orbitals as quasi p orbitals and then using angular-momentum coupling techniques. An analytic expression for the electric dipole absorption line strengths between 4fN multiplets and 4fN- 1 5d states is given in terms of various angular-momentum quantum numbers and re-coupling coefficients. The result is then applied to interpret the excitation spectrum of Cs2NaYF6：Er3＋. Tbe high-spin and lowspin states of Cs2NaYF6：Er3＋ are discussed in terms of the wavefunctions obtained by using the developed theoretical model.展开更多
We report comprehensive investigations into the structure of high-quality(111)-oriented SrRuO_(3)films on SrTiO_(3)substrates to elucidate the effect of(111)heteroepitaxial strain.We found that SrRuO_(3)film with a th...We report comprehensive investigations into the structure of high-quality(111)-oriented SrRuO_(3)films on SrTiO_(3)substrates to elucidate the effect of(111)heteroepitaxial strain.We found that SrRuO_(3)film with a thickness of~40 nm is compressively strained in plane on the substrate with full coherency.Nevertheless,the out-of-plane spacing is almost the same as in the bulk,which is at odds with the conventional paradigm.By probing a series of half-order Bragg reflections using synchrotron-based x-ray diffraction combined with analyses of the scanning transmission electron microscopy images,we discovered that the heteroepitaxial strain is accommodated via significant suppression of the degree of c+octahedral tilting and the formation of three equivalent domain structures on the(111)SrTiO_(3)substrate.This anomalous effect sheds light on the understanding of an unconventional paradigm of film-substrate coupling for the(111)heteroepitaxial strain.展开更多
The distribution of He in η-Fe2C has been studied by first-principles calculations.The formation energies of interstitial He and substitutional He（replacing Fe） are 3.76 eV and 3.49 eV,respectively,which are remark...The distribution of He in η-Fe2C has been studied by first-principles calculations.The formation energies of interstitial He and substitutional He（replacing Fe） are 3.76 eV and 3.49 eV,respectively,which are remarkably smaller than those in bcc Fe,indicating that He is more soluble in η-Fe2C than in bcc Fe.The binding potencies of both a substitutionalinterstitial He pair（1.28 eV） and a substitutional-substitutional He pair（0.76 eV） are significantly weaker than those in bcc Fe.The binding energy between the two He atoms in an interstitial-interstitial He pair（0.31 eV） is the same as that in bcc Fe,but the diffusion barrier of interstitial He（0.35 eV） is much larger than that in bcc Fe,suggesting that it is more difficult for the interstitial He atom to agglomerate in η-Fe2C than in bcc Fe.Thus,self-trapping of He in η-Fe2C is less powerful than that in bcc Fe.As a consequence,small and dense η-Fe2C particles in ferritic steels might serve as scattered trapping centers for He,slow down He bubble growth at the initial stage,and make the steel more swelling resistant.展开更多
This report presents a first-principles investigation of the structural, electronic, and optical properties of perovskite oxynitrides BaTaO2 N by means of density functional theory（DFT） calculations using the full-p...This report presents a first-principles investigation of the structural, electronic, and optical properties of perovskite oxynitrides BaTaO2 N by means of density functional theory（DFT） calculations using the full-potential linearized augmented plane wave（FP-LAPW） method. Three possible structures（P4mm, I4/mmm, and Pmma） are considered according to the TaO4N2 octahedral configurations. The calculated structural parameters are found to be in good agreement with the previous theoretical and experimental results. Moreover, the electronic band structure dispersion, total, and partial densities of electron states are investigated to explain the origin of bandgaps and the contribution of each orbital＇s species in the valence and the conduction bands. The calculated minimum bandgaps of the P4 mm, I4/mmm, and Pmma structures are 1.83 e V, 1.59 e V, and 1.49 e V, respectively. Furthermore, the optical properties represented by the dielectric functions calculated for BaTaO2 N show that the I4/mmm phase absorbs the light at a large window in both the visible and UV regions,whereas the other two structures（P4mm and Pmma） are more active in the UV region. Our investigations provide important information for the potential application of this material.展开更多
The yttrium iron garnet（YIG） samples are prepared at different temperatures from 900℃ to 1300℃ by the metalorganic decomposition（MOD） method. The chemical composition and crystal structure of the samples are stu...The yttrium iron garnet（YIG） samples are prepared at different temperatures from 900℃ to 1300℃ by the metalorganic decomposition（MOD） method. The chemical composition and crystal structure of the samples are studied by scanning electron microscope（SEM）, XRD, and Mossbauer spectrometer. It is shown that the ratio of ferric ions on two types of sites, the octahedral and the tetrahedral, is increased with the sintering temperature. At 1300℃, the pure garnet phase has been obtained, in which the ferric ions ratio is 2：3 leading to the minimum magnetic coercivity and maximum saturation magnetization. These results provide a route to synthesize pure YIG materials as the basic materials used in various spintronics applications.展开更多
基金Project supported by National Natural Science Foundation of China(Grant No.51920105011)the Key R&D Program of Liaoning Province of China(Grant No.2020JH2/10300079)。
文摘Using an effective field theory with correlations, magnetic properties of an octahedral chain described by a mixed spin Ising model are investigated. Unique phenomena such as multiple hysteresis loops, saturation magnetization, and reverse flip of the magnetization plateaus occur when certain typical parameters are applied. These results may be helpful to further investigate the magnetic properties of one-dimensional systems and could potentially be utilized in the design of spin devices.
基金Consejo Nacional de Ciencia y Tecnología of México (CONACYT) for her Doctoral scholarshippostgraduate studies department at CIMAVMonterrey for fellowship support。
文摘The tremendous potential of triboelectric generators-TENGs for converting mechanical energy into electrical energy places them as one of the most promising energy harvesting technologies. In this work, the fabrication of enhanced performance TENGs using Ag octahedron nano-assemblies on ITO as electrodes significantly increases the electric charge collection of the induced tribocharges. Thereby, nanostructured electrical contacts coated with Ag macroscale nano-assemblies with octahedral features were obtained by the electrodeposition technique on flexible PET/ITO substrates. Consequently, the nanostructured triboelectric generator-TENG exhibited 65 times more maximum output power, and almost 10 times more open circuit output voltage than that of a TENG with non-nanostructured contacts passing from μW to m W capabilities, which was attributed to the increment of intrinsic interface states due to a higher effective contact area in the former. Likewise, output performances of TENGs also displayed an asymptotic behavior on the output voltage as the operating frequency of the mechanical oscillations increased, which is attributed to a decrement in the internal impedance of the device with frequency. Furthermore, it is shown that the resulting electrical output power can successfully drive low power consumption electronic devices. On that account, the present research establishes a promising platform which contributes in an original way to the development of the TENGs technology.
文摘The structural, magnetic and electronic properties of the double perovskite Ba2SmNbO6 （for the simple cubic structure where no octahedral tilting exists anymore） are studied using the density functional theory within the generalized gradient approximation as well as taking into account the on-site Coulomb repulsive interaction. The total energy, the spin magnetic moment, the band structure and the density of states are calculated. The optimization of the lattice constants is 8.5173 A, which is in good agreement with the experimental value 8.5180 A. The calculations reveal that Ba2SmNbO6 has a stable ferromagnetic ground state and the spin magnetic moment per molecule is 5.00μB/f.u. which comes mostly from the Sin3＋ ion only. By analysis of the band structure, the compound exhibits the direct band gap material and half-metallic ferromagnetic nature with 100% spin-up polarization, which implies potential applications of this new lanthanide compound in magneto-electronic and spintronic devices.
基金supported by the National Natural Science Foundation of China (Grant No. 12174382)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant Nos. XDB0460000 and XDB28000000)the Innovation Program for Quantum Science and Technology (Grant Nos. 2024ZD0300104 and 2021ZD0302600)。
文摘The competition between dimensionality and ordering in multiferroic materials is of great interest for both fundamental physics and potential applications. Combining first-principles calculations with micromagnetic simulations, we investigate recently synthesized ultrathin perovskite bismuth ferrite(BFO) films. Our numerical results reveal that, at the monolayer limit, the ferroelectricity of BFO is missing because the octahedral distortions are constrained. However, the monolayer bismuth ferrite is a topological antiferromagnetic metal with tunable bimeron magnetic structure. The dual topologically non-trivial characteristics make monolayer bismuth ferrite a multifunctional building block in future spintronic devices.
基金fundings from the National Natural Science Foundation of China (Nos. 51872173 and 51772167)Taishan Scholarship of Young Scholars (No. tsqn201812068)+2 种基金Natural Science Foundation of Shandong Province (No. ZR2017JL020)Taishan Scholarship of Climbing Plan (No. tspd20161006)Key Research and Development Program of Shandong Province (No. 2018GGX102028)
文摘The biggest challenging issue in photocatalysis is efficient separation of the photoinduced carriers and the aggregation of photoexcited electrons on photocatalyst’s surface.In this paper,we report that double metallic co-catalysts Ti3C2 MXene and metallic octahedral(1T)phase tungsten disulfide(WS2)act pathways transferring photoexcited electrons in assisting the photocatalytic H2 evolution.TiO2 nanosheets were in situ grown on highly conductive Ti3C2 MXenes and 1T-WS2 nanoparticles were then uniformly distributed on TiO2@Ti3C2 composite.Thus,a distinctive 1T-WS2@TiO2@Ti3C2 composite with double metallic co-catalysts was achieved,and the content of 1T phase reaches 73%.The photocatalytic H2 evolution performance of 1T-WS2@TiO2@Ti3C2 composite with an optimized 15 wt%WS2 ratio is nearly 50 times higher than that of TiO2 nanosheets because of conductive Ti3C2 MXene and 1T-WS2 resulting in the increase of electron transfer efficiency.Besides,the 1T-WS2 on the surface of TiO2@Ti3C2 composite enhances the Brunauer–Emmett–Teller surface area and boosts the density of active site.
基金Project supported by the National Key Basic Research ProjectChina(Grant No.2014CB921002)+1 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB07030200)the National Natural Science Foundation of China(Grant Nos.51522212 and 51421002)
文摘Lattice,charge,orbital,and spin are the four fundamental degrees of freedom in condensed matter,of which the interactive coupling derives tremendous novel physical phenomena,such as high-temperature superconductivity（high-T_c SC） and colossal magnetoresistance（CMR） in strongly correlated electronic system.Direct experimental observation of these freedoms is essential to understanding the structure-property relationship and the physics behind it,and also indispensable for designing new materials and devices.Scanning transmission electron microscopy（STEM） integrating multiple techniques of structure imaging and spectrum analysis,is a comprehensive platform for providing structural,chemical and electronic information of materials with a high spatial resolution.Benefiting from the development of aberration correctors,STEM has taken a big breakthrough towards sub-angstrom resolution in last decade and always steps forward to improve the capability of material characterization;many improvements have been achieved in recent years,thereby giving an indepth insight into material research.Here,we present a brief review of the recent advances of STEM by some representative examples of perovskite transition metal oxides;atomic-scale mapping of ferroelectric polarization,octahedral distortions and rotations,valence state,coordination and spin ordering are presented.We expect that this brief introduction about the current capability of STEM could facilitate the understanding of the relationship between functional properties and these fundamental degrees of freedom in complex oxides.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2016YFA0401003,2017YFA0403502,and2020YFA0309100)the National Natural Science Foundation of China(Grant Nos.11974326,12074365,11804342,U2032218,and 51872278)+1 种基金the Fundamental Research Funds for the Central Universities,China(Grant Nos.WK2030000035 and WK2340000102)Hefei Science Center of Chinese Academy of Sciences(Grant No.2020HSC-UE014)。
文摘The interfacial enhanced ferromagnetism in maganite/ruthenate system is regarded as a promising path to broaden the potential of oxide-based electronic device applications.Here,we systematically studied the physical properties of La_(1-x)Ca_(x)MnO_(3)/SrRuO_(3)superlattices and compared them with the La1-x Cax MnO_(3)thin films and bulk compounds.The La_(1-x)Ca_(x)MnO_(3)/SrRuO_(3)superlattices exhibit significant enhancement of Curie temperature(TC)beyond the corresponding thin films and bulks.Based on these results,we constructed an extended phase diagram of La_(1-x)Ca_(x)MnO_(3)under interfacial engineering.We considered the interfacial charge transfer and structural proximity effects as the origin of the interfaceinduced high TC.The structural characterizations revealed a pronounced increase of B-O-B bond angle,which could be the main driving force for the high TCin the superlattices.Our work inspires a deeper understanding of the collective effects of interfacial charge transfer and structural proximity on the physical properties of oxide heterostructures.
基金supported by the National Natural Science Foundation of China(Grant Nos 10874173 and 10774140)
文摘The spin-orbit interaction of the 5d electron needs to be taken into account to give the proper energy structure for the 4fN-1 5d configuration of heavy lanthanide ions occupying a site with ligands forming an octahedron. This paper derives theoretical results for the energy structure by treating the t2 orbitals as quasi p orbitals and then using angular-momentum coupling techniques. An analytic expression for the electric dipole absorption line strengths between 4fN multiplets and 4fN- 1 5d states is given in terms of various angular-momentum quantum numbers and re-coupling coefficients. The result is then applied to interpret the excitation spectrum of Cs2NaYF6：Er3＋. Tbe high-spin and lowspin states of Cs2NaYF6：Er3＋ are discussed in terms of the wavefunctions obtained by using the developed theoretical model.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0303600)the National Natural Science Foundation of China(Grant No.11974409)the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB33000000)
文摘We report comprehensive investigations into the structure of high-quality(111)-oriented SrRuO_(3)films on SrTiO_(3)substrates to elucidate the effect of(111)heteroepitaxial strain.We found that SrRuO_(3)film with a thickness of~40 nm is compressively strained in plane on the substrate with full coherency.Nevertheless,the out-of-plane spacing is almost the same as in the bulk,which is at odds with the conventional paradigm.By probing a series of half-order Bragg reflections using synchrotron-based x-ray diffraction combined with analyses of the scanning transmission electron microscopy images,we discovered that the heteroepitaxial strain is accommodated via significant suppression of the degree of c+octahedral tilting and the formation of three equivalent domain structures on the(111)SrTiO_(3)substrate.This anomalous effect sheds light on the understanding of an unconventional paradigm of film-substrate coupling for the(111)heteroepitaxial strain.
基金Project supported by the Research Key Project of Science and Technology of Education Bureau of Henan Province,China(Grant Nos.14A140030,15A140032,15B150010,and 15A430037)the Innovation Talents Program of Science and Technology of Institution of Higher Education of Henan Province,China(Grant No.14HASTIT044)
文摘The distribution of He in η-Fe2C has been studied by first-principles calculations.The formation energies of interstitial He and substitutional He（replacing Fe） are 3.76 eV and 3.49 eV,respectively,which are remarkably smaller than those in bcc Fe,indicating that He is more soluble in η-Fe2C than in bcc Fe.The binding potencies of both a substitutionalinterstitial He pair（1.28 eV） and a substitutional-substitutional He pair（0.76 eV） are significantly weaker than those in bcc Fe.The binding energy between the two He atoms in an interstitial-interstitial He pair（0.31 eV） is the same as that in bcc Fe,but the diffusion barrier of interstitial He（0.35 eV） is much larger than that in bcc Fe,suggesting that it is more difficult for the interstitial He atom to agglomerate in η-Fe2C than in bcc Fe.Thus,self-trapping of He in η-Fe2C is less powerful than that in bcc Fe.As a consequence,small and dense η-Fe2C particles in ferritic steels might serve as scattered trapping centers for He,slow down He bubble growth at the initial stage,and make the steel more swelling resistant.
文摘This report presents a first-principles investigation of the structural, electronic, and optical properties of perovskite oxynitrides BaTaO2 N by means of density functional theory（DFT） calculations using the full-potential linearized augmented plane wave（FP-LAPW） method. Three possible structures（P4mm, I4/mmm, and Pmma） are considered according to the TaO4N2 octahedral configurations. The calculated structural parameters are found to be in good agreement with the previous theoretical and experimental results. Moreover, the electronic band structure dispersion, total, and partial densities of electron states are investigated to explain the origin of bandgaps and the contribution of each orbital＇s species in the valence and the conduction bands. The calculated minimum bandgaps of the P4 mm, I4/mmm, and Pmma structures are 1.83 e V, 1.59 e V, and 1.49 e V, respectively. Furthermore, the optical properties represented by the dielectric functions calculated for BaTaO2 N show that the I4/mmm phase absorbs the light at a large window in both the visible and UV regions,whereas the other two structures（P4mm and Pmma） are more active in the UV region. Our investigations provide important information for the potential application of this material.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11004095,11104134,61271077,50977042,and 10904061)
文摘The yttrium iron garnet（YIG） samples are prepared at different temperatures from 900℃ to 1300℃ by the metalorganic decomposition（MOD） method. The chemical composition and crystal structure of the samples are studied by scanning electron microscope（SEM）, XRD, and Mossbauer spectrometer. It is shown that the ratio of ferric ions on two types of sites, the octahedral and the tetrahedral, is increased with the sintering temperature. At 1300℃, the pure garnet phase has been obtained, in which the ferric ions ratio is 2：3 leading to the minimum magnetic coercivity and maximum saturation magnetization. These results provide a route to synthesize pure YIG materials as the basic materials used in various spintronics applications.
