基于完全对角化方法,研究了~4B_1(3d^3)态离子在四角对称晶场中的磁相互作用,分析了自旋哈密顿参量(b02,g∥,g⊥,Δg)的微观起源.结果表明在被考虑的大部分晶场区域,人们通常考虑的SO(spin orbit)磁相互作用的贡献最为重要;然而,对于零...基于完全对角化方法,研究了~4B_1(3d^3)态离子在四角对称晶场中的磁相互作用,分析了自旋哈密顿参量(b02,g∥,g⊥,Δg)的微观起源.结果表明在被考虑的大部分晶场区域,人们通常考虑的SO(spin orbit)磁相互作用的贡献最为重要;然而,对于零场分裂参量b02而言,来自其他机理(包括SS(spin orbit),SOO(spin other orbit),SO SS SOO)的贡献在大部分晶场区域超过了20%;在部分晶场区域,其他机理的贡献甚至超过SO机理的贡献.详细地分析了Macfarlane零场分裂参量b02近似三阶微扰理论的收敛性,结果表明该理论在大部分晶场区域收敛性较差.讨论了3d3态离子第一激发态2Eg分裂的微观起源.并利用群论方法解释了在C4v和C3v对称晶场中2Eg态分裂的不同机理.展开更多
Mixed alkali and alkaline earth oxide glasses of RO-Li2O-Na2O-K2O-B2O3(R = Zn, Mg, Sr and Ba) system were studied by electron paramagnetic resonance (EPR) and optical absorption spectroscopy. Cu2+ and VO2+ ions were u...Mixed alkali and alkaline earth oxide glasses of RO-Li2O-Na2O-K2O-B2O3(R = Zn, Mg, Sr and Ba) system were studied by electron paramagnetic resonance (EPR) and optical absorption spectroscopy. Cu2+ and VO2+ ions were used as the spin probes. The glasses containing 1 mole% of Cu2+ and 2mole% of VO2+ were prepared by the melt quenching method. X-ray diffraction studies of the samples did not reveal crystalline phases. EPR measurements were made at X-band frequencies with 100 kHz field modulation, at 310 K. Optical spectra were recorded in the wavelength range 300 nm - 800 nm. From the EPR spectra the spin-Hamiltonian parameters were evaluated. The spin-Hamiltonian parameter values in the case of Cu2+ indicated that the ground state of Cu2+ was orbital (2B1g) and the site symmetry around Cu2+ is tetragonally distorted octahedral. The variation of gll and All with the alkaline earth oxide (RO) composition was found to be non-linear which may be due to the change in the ligand field strength at the site of Cu2+ ions. From the spin-Hamiltonian parameters of VO2+, it was observed that the vanadyl ions exist as VO2+ ions in octahedral coordination with tetragonal compression and have C4V symmetry with ground state dxy. Tetragonality (△gll/△g) of V4+ ion sites exhibited non-linear variation with RO content, which indicated change in the ligand field at the site of V4+. A broad optical absorption band was observed in the glass containing Cu2+ ions corresponding to the 2B1g → 2B2g transition. From the EPR and optical data the bond parameters were evaluated. In the case of VO2+ ions, the covalency rates were estimated.展开更多
文摘基于完全对角化方法,研究了~4B_1(3d^3)态离子在四角对称晶场中的磁相互作用,分析了自旋哈密顿参量(b02,g∥,g⊥,Δg)的微观起源.结果表明在被考虑的大部分晶场区域,人们通常考虑的SO(spin orbit)磁相互作用的贡献最为重要;然而,对于零场分裂参量b02而言,来自其他机理(包括SS(spin orbit),SOO(spin other orbit),SO SS SOO)的贡献在大部分晶场区域超过了20%;在部分晶场区域,其他机理的贡献甚至超过SO机理的贡献.详细地分析了Macfarlane零场分裂参量b02近似三阶微扰理论的收敛性,结果表明该理论在大部分晶场区域收敛性较差.讨论了3d3态离子第一激发态2Eg分裂的微观起源.并利用群论方法解释了在C4v和C3v对称晶场中2Eg态分裂的不同机理.
文摘Mixed alkali and alkaline earth oxide glasses of RO-Li2O-Na2O-K2O-B2O3(R = Zn, Mg, Sr and Ba) system were studied by electron paramagnetic resonance (EPR) and optical absorption spectroscopy. Cu2+ and VO2+ ions were used as the spin probes. The glasses containing 1 mole% of Cu2+ and 2mole% of VO2+ were prepared by the melt quenching method. X-ray diffraction studies of the samples did not reveal crystalline phases. EPR measurements were made at X-band frequencies with 100 kHz field modulation, at 310 K. Optical spectra were recorded in the wavelength range 300 nm - 800 nm. From the EPR spectra the spin-Hamiltonian parameters were evaluated. The spin-Hamiltonian parameter values in the case of Cu2+ indicated that the ground state of Cu2+ was orbital (2B1g) and the site symmetry around Cu2+ is tetragonally distorted octahedral. The variation of gll and All with the alkaline earth oxide (RO) composition was found to be non-linear which may be due to the change in the ligand field strength at the site of Cu2+ ions. From the spin-Hamiltonian parameters of VO2+, it was observed that the vanadyl ions exist as VO2+ ions in octahedral coordination with tetragonal compression and have C4V symmetry with ground state dxy. Tetragonality (△gll/△g) of V4+ ion sites exhibited non-linear variation with RO content, which indicated change in the ligand field at the site of V4+. A broad optical absorption band was observed in the glass containing Cu2+ ions corresponding to the 2B1g → 2B2g transition. From the EPR and optical data the bond parameters were evaluated. In the case of VO2+ ions, the covalency rates were estimated.
