用固相法制备M型钡铁氧体Ba1-xLaxFe12-xCoxO19（x=0~0.45）,研究了取代量和烧结温度对材料致密化及磁性能的影响。结果表明,烧结样品的密度随烧结温度的升高而逐渐增大,并趋于稳定;在相同的烧结温度下,烧结样品的密度随取代量的增加而...用固相法制备M型钡铁氧体Ba1-xLaxFe12-xCoxO19（x=0~0.45）,研究了取代量和烧结温度对材料致密化及磁性能的影响。结果表明,烧结样品的密度随烧结温度的升高而逐渐增大,并趋于稳定;在相同的烧结温度下,烧结样品的密度随取代量的增加而减小。在1050℃烧结时,饱和磁化强度MS随取代量的增加而减小,磁晶各向异性场Ha随取代量的增加先增加后减小,Ha在取代量x=0.3时取得极大值630 k A/m。展开更多
Numerical simulations based on a new regularized phase-field model were presented, to simulate the solidification of hexagonal close-packed materials with strong interfacial energy anisotropies. Results show that the ...Numerical simulations based on a new regularized phase-field model were presented, to simulate the solidification of hexagonal close-packed materials with strong interfacial energy anisotropies. Results show that the crystal grows into facet dendrites,displaying six-fold symmetry. The size of initial crystals has an effect on the branching-off of the principal branch tip along the<100> direction, which is eliminated by setting the b/a(a and b are the semi-major and semi-minor sizes in the initial elliptical crystals, respectively) value to be less than or equal to 1. With an increase in the undercooling value, the equilibrium morphology of the crystal changes from a star-like shape to facet dendrites without side branches. The steady-state tip velocity increases exponentially when the dimensionless undercooling is below the critical value. With a further increase in the undercooling value, the equilibrium morphology of the crystal grows into a developed side-branch structure, and the steady-state tip velocity of the facet dendrites increases linearly. The facet dendrite growth has controlled diffusion and kinetics.展开更多
Based on the effective-field theory with self-spin correlations and the differential operator technique, physical properties of the spin-2 system with biaxial crystal field on the .simple cubic, body-centered cubic, a...Based on the effective-field theory with self-spin correlations and the differential operator technique, physical properties of the spin-2 system with biaxial crystal field on the .simple cubic, body-centered cubic, as well as faced-centered lattice have been studied. The influences of the external longitudinal magnetic field on the magnetization, internal energy, specific heat, and susceptibility have been discussed in detail The phenomenon that the magnetization in the ground state shows quantum effects produced by the biaxial transverse crystal field has been found.展开更多
Based on the strong magnetic anisotropy along the symmetry of the crystal, we construct a U（2） non-Abelian gauge potential for the molecular nanomagnet Mn12 by varying the external magnetic field adiabatically. More...Based on the strong magnetic anisotropy along the symmetry of the crystal, we construct a U（2） non-Abelian gauge potential for the molecular nanomagnet Mn12 by varying the external magnetic field adiabatically. Moreover, the non-Abelian geometric phase and the unitary matrix operation, which are tile key steps to realize the universal holonomic quantum computing in the degenerate subspace, are also obtained by means of choosing an evolution path properly.展开更多
采用固相法制备M型六角锶铁氧体(SrFe_(12)O_(19))材料,利用Bi_2O_3作为烧结助剂以改善材料的低温烧结特性,系统研究了材料的晶体结构、电学性能和磁学性能。结果表明:当烧结温度降低至900℃时可以获得单相的SrFe_(12)O_(19)铁氧体材料...采用固相法制备M型六角锶铁氧体(SrFe_(12)O_(19))材料,利用Bi_2O_3作为烧结助剂以改善材料的低温烧结特性,系统研究了材料的晶体结构、电学性能和磁学性能。结果表明:当烧结温度降低至900℃时可以获得单相的SrFe_(12)O_(19)铁氧体材料。Bi_2O_3的添加对低温烧结材料的电学性能和磁学性能影响显著,可以提高材料的电阻率ρ、饱和磁化强度M_s、內禀矫顽力H_(ci)和磁晶各向异性场H_a。低温烧结材料的ρ、M_s、H_(ci)和H_a分别可以达到0.42×10~8?·cm、285.6 k A·m^(-1)、347.3 kA·m^(-1)和1546.6 kA·m^(-1),在非互易LTCC(低温共烧陶瓷)铁氧体器件领域具有重要的应用前景。展开更多
Polarized upconversion luminescence(UCL)of lanthanide-doped micro/nano-crystals has shown great promise in single-particle tracking and super-resolution bioimaging.However,because of the spectral line broadening and m...Polarized upconversion luminescence(UCL)of lanthanide-doped micro/nano-crystals has shown great promise in single-particle tracking and super-resolution bioimaging.However,because of the spectral line broadening and multiple sites of lanthanide in upconversion particles(UCPs),the crystal-field(CF)polarization components of UCL are usually undistinguishable.Herein,we report the linearly polarized UCL in LiLuF_(4):Yb^(3+)/Er^(3+) single microcrystals with resolvable CF transition lines and a polarization degree up to 0.82.The CF levels and CF transition lines of Er^(3+),as well as their emission polarization anisotropy,are unraveled for the first time through low-temperature and high-resolution photoluminescence(PL)and UCL spectroscopies.By taking advantage of the well-resolved and highly-polarized CF transition lines of Er^(3+),we demonstrate the application of LiLuF_(4):Yb^(3+)/Er^(3+) single microcrystals as anisotropic UCL probes for orientation tracking.These findings provide fundamental insights into the polarization anisotropy of UCL in lanthanide-doped single particles,thus laying a foundation for the future design of anisotropic luminescent probes towards versatile applications.展开更多
Magnetic Fe films grown on single-crystal Mg O(001) and(011) substrates were prepared by direct current magnetron sputtering. The experimental results showed that by applying an external magnetic field of about 300 Oe...Magnetic Fe films grown on single-crystal Mg O(001) and(011) substrates were prepared by direct current magnetron sputtering. The experimental results showed that by applying an external magnetic field of about 300 Oe to film during deposition, a fourfold cubic magnetic anisotropy on Mg O(001) substrate and a twofold uniaxial magnetic anisotropy on Mg O(011) substrate were generated, compared to the isotropic magnetization of Fe film grown without applying the external magnetic field.Our results suggested that external magnetic field during preparation effectively induced relatively higher surface mobility of sputtered Fe atoms and further promoted the crystallization of Fe film and the enhancement of magnetic anisotropy.展开更多
基金supported by the National Natural Science Foundation of China(Grant Numbers 51702285,51772269)the Zhejiang Provincial Natural Science Foundation(Grant Number LY17F040003).
文摘用固相法制备M型钡铁氧体Ba1-xLaxFe12-xCoxO19（x=0~0.45）,研究了取代量和烧结温度对材料致密化及磁性能的影响。结果表明,烧结样品的密度随烧结温度的升高而逐渐增大,并趋于稳定;在相同的烧结温度下,烧结样品的密度随取代量的增加而减小。在1050℃烧结时,饱和磁化强度MS随取代量的增加而减小,磁晶各向异性场Ha随取代量的增加先增加后减小,Ha在取代量x=0.3时取得极大值630 k A/m。
基金Project(10834015) supported by the National Natural Science Foundation of ChinaProject(12SKY01-1) supported by the Doctoral Fund of Shangluo University,ChinaProject(14JK1223) supported by the Scientific Research Program of Shaanxi Provincial Education Department,China
文摘Numerical simulations based on a new regularized phase-field model were presented, to simulate the solidification of hexagonal close-packed materials with strong interfacial energy anisotropies. Results show that the crystal grows into facet dendrites,displaying six-fold symmetry. The size of initial crystals has an effect on the branching-off of the principal branch tip along the<100> direction, which is eliminated by setting the b/a(a and b are the semi-major and semi-minor sizes in the initial elliptical crystals, respectively) value to be less than or equal to 1. With an increase in the undercooling value, the equilibrium morphology of the crystal changes from a star-like shape to facet dendrites without side branches. The steady-state tip velocity increases exponentially when the dimensionless undercooling is below the critical value. With a further increase in the undercooling value, the equilibrium morphology of the crystal grows into a developed side-branch structure, and the steady-state tip velocity of the facet dendrites increases linearly. The facet dendrite growth has controlled diffusion and kinetics.
基金The project supported by the Natural Science Foundation of Liaoning Province under Grant＇ No. 20041021, the Scientific Research Foundation of the Educational Department of Liaoning Province under Grant No. 2004C006, and National Natural Science Foundation of China under Grant No. 50477049.
文摘Based on the effective-field theory with self-spin correlations and the differential operator technique, physical properties of the spin-2 system with biaxial crystal field on the .simple cubic, body-centered cubic, as well as faced-centered lattice have been studied. The influences of the external longitudinal magnetic field on the magnetization, internal energy, specific heat, and susceptibility have been discussed in detail The phenomenon that the magnetization in the ground state shows quantum effects produced by the biaxial transverse crystal field has been found.
基金Supported by the National Natural Science Foundation of China under Grant Nos. 11074154, 11074184, and 11075099the National Science Funding of Zhejiang Province under Grant No. Y6090001
文摘Based on the strong magnetic anisotropy along the symmetry of the crystal, we construct a U（2） non-Abelian gauge potential for the molecular nanomagnet Mn12 by varying the external magnetic field adiabatically. Moreover, the non-Abelian geometric phase and the unitary matrix operation, which are tile key steps to realize the universal holonomic quantum computing in the degenerate subspace, are also obtained by means of choosing an evolution path properly.
基金Scientific Research Foundation of Education Office of Sichuan Province(13Z198)Young and Middle-aged Academic Leaders of Scientific Research Funds of Chengdu University of Information Technology(J201222)
文摘采用固相法制备M型六角锶铁氧体(SrFe_(12)O_(19))材料,利用Bi_2O_3作为烧结助剂以改善材料的低温烧结特性,系统研究了材料的晶体结构、电学性能和磁学性能。结果表明:当烧结温度降低至900℃时可以获得单相的SrFe_(12)O_(19)铁氧体材料。Bi_2O_3的添加对低温烧结材料的电学性能和磁学性能影响显著,可以提高材料的电阻率ρ、饱和磁化强度M_s、內禀矫顽力H_(ci)和磁晶各向异性场H_a。低温烧结材料的ρ、M_s、H_(ci)和H_a分别可以达到0.42×10~8?·cm、285.6 k A·m^(-1)、347.3 kA·m^(-1)和1546.6 kA·m^(-1),在非互易LTCC(低温共烧陶瓷)铁氧体器件领域具有重要的应用前景。
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(CAS,XDB20000000)the National Natural Science Foundation of China(U1805252,21875250,11774345,12074379,21771185,12074380,and 21975257)+1 种基金the Youth Innovation Promotion Association of the CAS(2020305)the Natural Science Foundation of Fujian Province(2020I0037).
文摘Polarized upconversion luminescence(UCL)of lanthanide-doped micro/nano-crystals has shown great promise in single-particle tracking and super-resolution bioimaging.However,because of the spectral line broadening and multiple sites of lanthanide in upconversion particles(UCPs),the crystal-field(CF)polarization components of UCL are usually undistinguishable.Herein,we report the linearly polarized UCL in LiLuF_(4):Yb^(3+)/Er^(3+) single microcrystals with resolvable CF transition lines and a polarization degree up to 0.82.The CF levels and CF transition lines of Er^(3+),as well as their emission polarization anisotropy,are unraveled for the first time through low-temperature and high-resolution photoluminescence(PL)and UCL spectroscopies.By taking advantage of the well-resolved and highly-polarized CF transition lines of Er^(3+),we demonstrate the application of LiLuF_(4):Yb^(3+)/Er^(3+) single microcrystals as anisotropic UCL probes for orientation tracking.These findings provide fundamental insights into the polarization anisotropy of UCL in lanthanide-doped single particles,thus laying a foundation for the future design of anisotropic luminescent probes towards versatile applications.
基金supported by the National Natural Science Foundation of China(51332001 and 51402164)Tsinghua University Initiative Scientific Research Program(2014Z21010 and 2014Z01006)
文摘Magnetic Fe films grown on single-crystal Mg O(001) and(011) substrates were prepared by direct current magnetron sputtering. The experimental results showed that by applying an external magnetic field of about 300 Oe to film during deposition, a fourfold cubic magnetic anisotropy on Mg O(001) substrate and a twofold uniaxial magnetic anisotropy on Mg O(011) substrate were generated, compared to the isotropic magnetization of Fe film grown without applying the external magnetic field.Our results suggested that external magnetic field during preparation effectively induced relatively higher surface mobility of sputtered Fe atoms and further promoted the crystallization of Fe film and the enhancement of magnetic anisotropy.
