The experimental monoclinic CF parameter （CFP） sets obtained by Duan et al. （Phys. Rev. B 75 （2007） 195130） for Er3＋ and Nd3＋ ions in YAIO3 were reanalyzed. These CFPs fitted using R-approach, i.e. with the mo...The experimental monoclinic CF parameter （CFP） sets obtained by Duan et al. （Phys. Rev. B 75 （2007） 195130） for Er3＋ and Nd3＋ ions in YAIO3 were reanalyzed. These CFPs fitted using R-approach, i.e. with the monoclinic second-rank CFP set to zero, and additionally with one six-rank CFP fixed to zero, turned out to be non-standard. In order to understand better the low symmetry aspects involved in the fitted CFPs and extract useful structtral information inherent in monoclinic CFPs, an approach comprising four methods was utilized. First, superposition model （SPM） was applied to calculate CFPs in the crystallographic axis system. Second, the principal values for the SPM determined CFPs and the orientation of the principal axis system w.r.t, the crystallographic axis system were obtained using the procedure 3DD for diagonalization of the 2rid-rank CFPs. Third, analysis of higher symmetry approximations, i.e. orthorhombic and tea＇agonal, was carried out using the pseudosymmetry axes method. Fourth, the closeness factors and norm ratios were employed for quantitative comparisons of various CFP sets. Partial results for Er3＋ ions in YAlO3 were presented here, whereas detailed results would be given in a follow-up paper.展开更多
The three sets of crystal field parameters （CFPs） obtained from spectroscopic and magnetic susceptibility studies of Tb3＋（4f^8） ions in TbAlO3 by Gruber et al. （J. Lumin. 128 （2008） 1271） were reanalyzed. The...The three sets of crystal field parameters （CFPs） obtained from spectroscopic and magnetic susceptibility studies of Tb3＋（4f^8） ions in TbAlO3 by Gruber et al. （J. Lumin. 128 （2008） 1271） were reanalyzed. These sets, fitted from experimental energy levels, are physically equivalent and correspond to specific choices of the axis system. Proper interpretation of experimental data for Tb3＋ ions at monoclinic C8 symmetry sites in TbAlO3 crystal requires clarification of several intricate low syrmnetry aspects, namely, （a） three equivalent forms of monoclinic CF Hamiltouian, （b） relative orientation of the crystallographic axis system w.r.t, the symmetry-adapted axis system, （c） monoclinic standardization of CFPs, （d） distinction between the actual and apparent low symmetry effects exhibited by CFPs, and （e） nominal nature of all fitted CFP sets. For this purpose, modeling of CFPs for Tb3＋ in TbAlO3 was carried out using at the first stage only the Coulomb, i.e. point charge, eonlribntions in the exchange charge model. The point charge model calculated CFPs disagree with the experimental CFPs, especially the rank k=6 CFPs. To explain this discrepancy and to verify the correcmess of the theoretical CFP calculations additionally the superposition model was employed. The methods of analysis and modeling of CFP sets for monoclinic symmetry cases proposed here proved useful for the studied case as well as might be used for other ion-host systems exhibiting monoclinic or triclinic local site symmetry. Partial results for Tb3＋ ions in TbAlO3 were presented here, whereas detailed results were given in a follow-up paper.展开更多
基金supported by the research grant from the Polish Ministry of Science and Tertiary Education in the years 2006-2009
文摘The experimental monoclinic CF parameter （CFP） sets obtained by Duan et al. （Phys. Rev. B 75 （2007） 195130） for Er3＋ and Nd3＋ ions in YAIO3 were reanalyzed. These CFPs fitted using R-approach, i.e. with the monoclinic second-rank CFP set to zero, and additionally with one six-rank CFP fixed to zero, turned out to be non-standard. In order to understand better the low symmetry aspects involved in the fitted CFPs and extract useful structtral information inherent in monoclinic CFPs, an approach comprising four methods was utilized. First, superposition model （SPM） was applied to calculate CFPs in the crystallographic axis system. Second, the principal values for the SPM determined CFPs and the orientation of the principal axis system w.r.t, the crystallographic axis system were obtained using the procedure 3DD for diagonalization of the 2rid-rank CFPs. Third, analysis of higher symmetry approximations, i.e. orthorhombic and tea＇agonal, was carried out using the pseudosymmetry axes method. Fourth, the closeness factors and norm ratios were employed for quantitative comparisons of various CFP sets. Partial results for Er3＋ ions in YAlO3 were presented here, whereas detailed results would be given in a follow-up paper.
基金supported by the research grant from the Polish Ministry of Science and Tertiary Education in the years 2006-2009
文摘The three sets of crystal field parameters （CFPs） obtained from spectroscopic and magnetic susceptibility studies of Tb3＋（4f^8） ions in TbAlO3 by Gruber et al. （J. Lumin. 128 （2008） 1271） were reanalyzed. These sets, fitted from experimental energy levels, are physically equivalent and correspond to specific choices of the axis system. Proper interpretation of experimental data for Tb3＋ ions at monoclinic C8 symmetry sites in TbAlO3 crystal requires clarification of several intricate low syrmnetry aspects, namely, （a） three equivalent forms of monoclinic CF Hamiltouian, （b） relative orientation of the crystallographic axis system w.r.t, the symmetry-adapted axis system, （c） monoclinic standardization of CFPs, （d） distinction between the actual and apparent low symmetry effects exhibited by CFPs, and （e） nominal nature of all fitted CFP sets. For this purpose, modeling of CFPs for Tb3＋ in TbAlO3 was carried out using at the first stage only the Coulomb, i.e. point charge, eonlribntions in the exchange charge model. The point charge model calculated CFPs disagree with the experimental CFPs, especially the rank k=6 CFPs. To explain this discrepancy and to verify the correcmess of the theoretical CFP calculations additionally the superposition model was employed. The methods of analysis and modeling of CFP sets for monoclinic symmetry cases proposed here proved useful for the studied case as well as might be used for other ion-host systems exhibiting monoclinic or triclinic local site symmetry. Partial results for Tb3＋ ions in TbAlO3 were presented here, whereas detailed results were given in a follow-up paper.
