B位异价离子(Al,Cr)置换对Li_(3x)La_(2/3-x)TiO_3离子电导率的影响

Effects of B-site Ion(Al, Cr) Substitution on the Ionic Conductivity of

研究了B位Al,Cr异价离子置换对Li3xLa2/3-xTiO3(x=0.13)离子电导率的影响。结果表明:用适量离子半径较小的Al3+(0.535A)置换Ti4+(0.605A)可有效地提高其离子电导率,当B位铝离子的置换量为y=0.02时,组分为(Li0.39La0.54)1+y/2AlyTi1-yO3的材料其室温下的体离子电导率σb=(1.58d:0.01)×10-3S·cm-1,这一结果是迄今为止钙钛矿锂离子导体材料文献报道的最好水平。然而,分析结果表明,离子电导率的提高难以用锂离子迁移“瓶颈”尺寸的变化,TiO6八面体张缩能力及A位阳离子和空位的有序性来解释,因B位异价离子置换而引发的Li+离子键强度的变化被认为是导致锂离子电导率提高的原因。

The effect of B-Site aliovalent ion (Al, Cr) substitution on the ionic conductivity of Li3xLa2/3-xTiO3 was investigated. The results show that partial substitution of smaller Al3+ for Ti4+ is effective to enhance the ionic conductivity of Li3xLa2/3-xTiO3. At 300K, the maximum bulk conductivity of (1.58±0.01) × 10-3S·cm-1 observed from the composition of (Li0.39La0.54)1+y/2 AlyTi1-yO3 with y=0.02(x=0.13), is the highest yet reported for known perovskite solutions at room temperature. The conductivity enhancement is due to the substitution-induced bond strength change rather than due to bottleneck size change for Li migration, TiO6-octahedron tilting or A-site cation ordering.