By using the re-derived formulae for both line-strength of electricdipole transition and simple J-mixing coefficients within the 4f shell in a rare-earthion, the spectroscopic properties of the luminescent material Eu...By using the re-derived formulae for both line-strength of electricdipole transition and simple J-mixing coefficients within the 4f shell in a rare-earthion, the spectroscopic properties of the luminescent material Eu3+ =Y2O3 and laser crystals Tb3+:=YAlO3 and Nd3+:YVO4, are investigated in detail. On the basis of three fitting Ω parameters and the effective reduced matrix elements, the spectral linestrengths, spontaneous emission probabilities, fluorescent branching ratios and lifetimeare calculated. The better agreement between theoretical results and experimental dataindicates the importance of J-mixing in the spectroscopic study of laser crystals.展开更多
Any electronic eigenstate of the paramagnetic ion open-shell is characterized by the three independent multipole asphericities for and 6 related to the second moments of the relevant crystal-field splittings by , wher...Any electronic eigenstate of the paramagnetic ion open-shell is characterized by the three independent multipole asphericities for and 6 related to the second moments of the relevant crystal-field splittings by , where . The Ak as the reduced matrix elements can serve as a reliable measure of the state capability for the splitting produced by the k-rank component of the crystal-field Hamiltonian. These multipolar characteristics allow one to verify any fitted crystal-field parameter set by comparing the calculated second moments and the experimental ones of the relevant crystal-field splittings. We present the multipole characteristics Ak for the extensive set of eigenstates from the lower parts of energy spectra of the tripositive 4 f N ions applying in the calculations the improved eigenfunctions of the free lanthanide ions obtained based on the M. Reid f-shell programs. Such amended asphericities are compared with those achieved for the simplified Russell-Saunders states. Next, they are classified with respect to the absolute or relative weight of Ak in the multipole structure of the considered states. For the majority of the analyzed states (about 80%) the Ak variation is of order of only a few percent. Some essential changes are found primarily for several states of Tm3+, Er3+, Nd3+, and Pr3+ ions. The detailed mechanisms of such Ak changes are unveiled. Particularly, certain noteworthy cancelations as well as enhancements of their magnitudes are explained.展开更多
<正> The transverse spin-2 Ising ferromagnetic model with a longitudinal crystal-field is studied within themean-field theory based on Bogoliubov inequality for the Gibbs free energy.The ground-state phase diagr...<正> The transverse spin-2 Ising ferromagnetic model with a longitudinal crystal-field is studied within themean-field theory based on Bogoliubov inequality for the Gibbs free energy.The ground-state phase diagram and thetricritical point are obtained in the transverse field Ω/zJ-longitudinal crystal D/zJ field plane.We find that there are thefirst order-order phase transitions in a very small range of D/zJ besides the usual first order-disorder phase transitionsand the second order-disorder phase transitions.展开更多
We report on the first high-resolution study of LiLuF4:Tm3+. The accurate energy level scheme of Tm3+ in the LiLuF4 matrix was obtained for the 3H6,5,4, 3F4,3,2, and 1G4 multiplets. It was shown that electric-dipole t...We report on the first high-resolution study of LiLuF4:Tm3+. The accurate energy level scheme of Tm3+ in the LiLuF4 matrix was obtained for the 3H6,5,4, 3F4,3,2, and 1G4 multiplets. It was shown that electric-dipole transitions dominate for all the studied multiplets except the 3H5 one.展开更多
Based on the first-principle calculations for 3D Hofmann-like spin-crossover (SCO) compound [Fe(C4H4N2){Pt(CN)4}], the discrepancy of transition mechanism is clarified with quantitatively distinguishable evidence of s...Based on the first-principle calculations for 3D Hofmann-like spin-crossover (SCO) compound [Fe(C4H4N2){Pt(CN)4}], the discrepancy of transition mechanism is clarified with quantitatively distinguishable evidence of second order phase transition. It shows that the stretch around 0.2 ? of Fe-N bond length leads to the continuous structure expansion, as the energy splitting ΔEHL between low-spin and high-spin states reduces from 2.554 2 eV to -0.327 8 eV, and the crystal-field splitting (CFS) is reduced from 1.845 8 eV to 0.420 8 eV meanwhile. A physics image relating the calculations results with CFS in the frame of ligand-field theory is presented, which manifests that CFS is a necessary parameter to be introduced directly in the theory of spin-state transition.展开更多
A mean-field approximation (MFA) is used to treat the crystal-field and transverse-field effects of the spin-1 Ising modle in the presence of longitudinal field. In spite of its simplicity, this scheme still gives the...A mean-field approximation (MFA) is used to treat the crystal-field and transverse-field effects of the spin-1 Ising modle in the presence of longitudinal field. In spite of its simplicity, this scheme still gives the satisfied results.展开更多
The 4f-5d transitions of Er3+ ions doped in crystals were widely studi ed due to their potential applications in quantum cutting phosphors and VUV lase rs,etc.The theory to do the calculations of 4f-5d transitions and...The 4f-5d transitions of Er3+ ions doped in crystals were widely studi ed due to their potential applications in quantum cutting phosphors and VUV lase rs,etc.The theory to do the calculations of 4f-5d transitions and various rela ted aspects,such as the ways to determining various parameters,were summarized .The impacts of various interactions on the spectra were also demonstrated clea rly with Er3+ ions in crystals CaF2 and LiYF4.Predicted results were compared w ith measured spectra.展开更多
As a promising narrow-band phosphor,SrLiAl_(3)N_(4)has a seemingly ultra-small total crystal-field splitting of only 2400 cm^(-1)with Ce^(3+)as dopant ions.This paper is devoted to unravel this anomalous phenomenon ba...As a promising narrow-band phosphor,SrLiAl_(3)N_(4)has a seemingly ultra-small total crystal-field splitting of only 2400 cm^(-1)with Ce^(3+)as dopant ions.This paper is devoted to unravel this anomalous phenomenon based on semi-quantitative crystal-field calculations.The results show that there may exist undetected excitation peaks immersed in the host excitation band,and the calibrated crystal-field splitting is 27000 cm^(-1).comparable to those of other Ce^(3+)doped phosphors.In the end the effect of polyhedral deformation on energy level is briefly discussed.展开更多
We report on the crystal-field(CF)levels of Nd^3+in Nd3CrGe3Be2O14,a representative of recently synthesized Be-containing langasites.They are the first in the family to contain two magnetic subsystems,1 D chromium and...We report on the crystal-field(CF)levels of Nd^3+in Nd3CrGe3Be2O14,a representative of recently synthesized Be-containing langasites.They are the first in the family to contain two magnetic subsystems,1 D chromium and Kagome-like rare-earth ones.High-resolution broad-band temperature-dependent spectra allow us to find all five CF Kramers doublets of the ground 4I9/2 CF multiplet and 38 levels of the excited 4I11/2,13/2,15/2,4F3/2,4F5/2+2H9/2,4F7/2+4S3/2 and 4F9/2 CF multiplets.These data form a basis for a future exploration of this interesting two-sublattice magnet with frustrated interactions.Optical transitions between Kramers doublets of Nd^3+indicate magnetic activity of 1D-chromium chains at T<20 K.展开更多
文摘By using the re-derived formulae for both line-strength of electricdipole transition and simple J-mixing coefficients within the 4f shell in a rare-earthion, the spectroscopic properties of the luminescent material Eu3+ =Y2O3 and laser crystals Tb3+:=YAlO3 and Nd3+:YVO4, are investigated in detail. On the basis of three fitting Ω parameters and the effective reduced matrix elements, the spectral linestrengths, spontaneous emission probabilities, fluorescent branching ratios and lifetimeare calculated. The better agreement between theoretical results and experimental dataindicates the importance of J-mixing in the spectroscopic study of laser crystals.
文摘Any electronic eigenstate of the paramagnetic ion open-shell is characterized by the three independent multipole asphericities for and 6 related to the second moments of the relevant crystal-field splittings by , where . The Ak as the reduced matrix elements can serve as a reliable measure of the state capability for the splitting produced by the k-rank component of the crystal-field Hamiltonian. These multipolar characteristics allow one to verify any fitted crystal-field parameter set by comparing the calculated second moments and the experimental ones of the relevant crystal-field splittings. We present the multipole characteristics Ak for the extensive set of eigenstates from the lower parts of energy spectra of the tripositive 4 f N ions applying in the calculations the improved eigenfunctions of the free lanthanide ions obtained based on the M. Reid f-shell programs. Such amended asphericities are compared with those achieved for the simplified Russell-Saunders states. Next, they are classified with respect to the absolute or relative weight of Ak in the multipole structure of the considered states. For the majority of the analyzed states (about 80%) the Ak variation is of order of only a few percent. Some essential changes are found primarily for several states of Tm3+, Er3+, Nd3+, and Pr3+ ions. The detailed mechanisms of such Ak changes are unveiled. Particularly, certain noteworthy cancelations as well as enhancements of their magnitudes are explained.
文摘<正> The transverse spin-2 Ising ferromagnetic model with a longitudinal crystal-field is studied within themean-field theory based on Bogoliubov inequality for the Gibbs free energy.The ground-state phase diagram and thetricritical point are obtained in the transverse field Ω/zJ-longitudinal crystal D/zJ field plane.We find that there are thefirst order-order phase transitions in a very small range of D/zJ besides the usual first order-disorder phase transitionsand the second order-disorder phase transitions.
基金supported by the Russian Academy of Sciences under the grant of the Program "Quantum physics of condensed matter"the grant 09-02-01067-a of the Russian Foundation for Basic Research
文摘We report on the first high-resolution study of LiLuF4:Tm3+. The accurate energy level scheme of Tm3+ in the LiLuF4 matrix was obtained for the 3H6,5,4, 3F4,3,2, and 1G4 multiplets. It was shown that electric-dipole transitions dominate for all the studied multiplets except the 3H5 one.
基金Supported by the Major State Basic Research Development of China(973 Program)(No.2006CB921606)the Ministry of Education(No.309020)
文摘Based on the first-principle calculations for 3D Hofmann-like spin-crossover (SCO) compound [Fe(C4H4N2){Pt(CN)4}], the discrepancy of transition mechanism is clarified with quantitatively distinguishable evidence of second order phase transition. It shows that the stretch around 0.2 ? of Fe-N bond length leads to the continuous structure expansion, as the energy splitting ΔEHL between low-spin and high-spin states reduces from 2.554 2 eV to -0.327 8 eV, and the crystal-field splitting (CFS) is reduced from 1.845 8 eV to 0.420 8 eV meanwhile. A physics image relating the calculations results with CFS in the frame of ligand-field theory is presented, which manifests that CFS is a necessary parameter to be introduced directly in the theory of spin-state transition.
文摘A mean-field approximation (MFA) is used to treat the crystal-field and transverse-field effects of the spin-1 Ising modle in the presence of longitudinal field. In spite of its simplicity, this scheme still gives the satisfied results.
基金Project supported by the National Natural Science Foundation of China (10874173,10704090,11074315,11011120083)the Foundation of the Education Committee of Chongqing (KJ090523)the Knowledge Innovation Project of the Chinese Academy of Sciences (KJCX2-YW-M1)
文摘The 4f-5d transitions of Er3+ ions doped in crystals were widely studi ed due to their potential applications in quantum cutting phosphors and VUV lase rs,etc.The theory to do the calculations of 4f-5d transitions and various rela ted aspects,such as the ways to determining various parameters,were summarized .The impacts of various interactions on the spectra were also demonstrated clea rly with Er3+ ions in crystals CaF2 and LiYF4.Predicted results were compared w ith measured spectra.
基金Projects supported by the National Natural Science Foundation of China(51832005,51602019).
文摘As a promising narrow-band phosphor,SrLiAl_(3)N_(4)has a seemingly ultra-small total crystal-field splitting of only 2400 cm^(-1)with Ce^(3+)as dopant ions.This paper is devoted to unravel this anomalous phenomenon based on semi-quantitative crystal-field calculations.The results show that there may exist undetected excitation peaks immersed in the host excitation band,and the calibrated crystal-field splitting is 27000 cm^(-1).comparable to those of other Ce^(3+)doped phosphors.In the end the effect of polyhedral deformation on energy level is briefly discussed.
基金Project supported by the Russian Foundation for Basic Research(17-02-00603)
文摘We report on the crystal-field(CF)levels of Nd^3+in Nd3CrGe3Be2O14,a representative of recently synthesized Be-containing langasites.They are the first in the family to contain two magnetic subsystems,1 D chromium and Kagome-like rare-earth ones.High-resolution broad-band temperature-dependent spectra allow us to find all five CF Kramers doublets of the ground 4I9/2 CF multiplet and 38 levels of the excited 4I11/2,13/2,15/2,4F3/2,4F5/2+2H9/2,4F7/2+4S3/2 and 4F9/2 CF multiplets.These data form a basis for a future exploration of this interesting two-sublattice magnet with frustrated interactions.Optical transitions between Kramers doublets of Nd^3+indicate magnetic activity of 1D-chromium chains at T<20 K.
