Li3VO4-Li4TO4(T=Ge,Si)固溶体离子导体7Li的NMR研究

在150—573K温度范围内,研究了固溶体Li₃VO₄-Li₄TO₄(T=Ge,Si)系统不同成分的⁷Li的NMR谱。发现γ_II相固溶体室温⁷Li的NMR线宽和自旋晶格弛豫时间T₁的值都比Li₄GeO₄,Li₄SiO₄和Li₃VO₄小约一个数量级。这表明在γ_II相固溶体离子导体中,Li⁺离子运动有可能比固溶前有数量级增长。同时还发现⁷Li的电四极分裂伴线数随成分和温度而异,以及伴线强度百分比依赖于温度。这反映γ_II相的不同成分中,间隙Li⁺离子占有的不等价位置个数不同,而Li⁺离子在每个不等价位置上的占有率又随温度而变化。关键词：

7Li NMR STUDIES ON IONIC CONDUCTOR IN THE SOLID SOLUTIONS Li3VO4-Li4TO4 (T = Ge, Si)

The ⁷Li NMR spectra of the solid solutions between Li₃VO₄ and Li₄TO₄ (T=Ge, Si) with different composition were investigated in the range 150-573 K. It was found that the values of ⁷Li NMR linewidth and spin-lattice relaxation time T₁ in γ_II phase solid solutions are about an order of magnitude less than that of Li₄GeO₄, Li₄SiO₄, and Li₃VO₄ at room temperature. The temperature dependence of the number and the intensity ratio of ⁷Li NMR quadrupole satellite lines, and the composition dependence of the former were observed. It is suggested that the Li⁺ ions in samples of γ_II structural compositions move probably about one order of magnitude faster than that of the three pure compounds. The number of inequivalent sites occupied by the Li⁺ ions changes with the composition. The occupancy of the Li⁺ ions in the inequivalent sites changes with the temperature.