非晶锂离子导体B2O3-0.7Li2O-0.7LiCl-xAl2O3晶化初期的核磁共振研究

通过真空密封热处理、避免了样品晶化后吸水引起的误差,采用脉冲法在293K和77K测量了晶化过程初期三种非晶锂离子导体B₂O₃-0.7Li₂O-0.7LiCl-xAl₂O₃(x=0.15,0.10和0.05)的⁷Li核磁共振谱。发现在低温(77K)只有固相锂离子对应的自旋-自旋弛豫时间T₂=87μs,严格按高斯函数衰减。在室温下固相锂离子对应的T_2s=127μs,仍是高斯型;但液相锂离子对应的T₂却按洛仑兹函数衰减。这反映出锂离子导体的固-液二相性。三种非晶B₂O₃-0.7Li₂O-0.7LiCl-xAl₂O₃(x=0.15,0.10和0.05)分别在热处理温度401,388和381℃附近,其液相锂离子对应的T_2l都剧增,其吸收谱线宽都变窄。由此再次验证了非晶母体与微晶之间的两相界面效应的物理图象。 关键词：

7Li NMR INVESTIGATIONS DURING PER-CRYSTALLIZATION PROCESS IN AMORPHOUS IONIC CONDUCTOR B2O3- 0.7Li2O-0.7LiCl-xAl2O3

To avoid absorbing moisture from the air, we have sealed all samples in high vacuum, and performed ⁷Li NMR investigations during pre-crystallization process of amorphous ionic conductor B₂O₃-0.7Li₂O-0.7LiCl-xAl₂O₃(x = 0.15, 0.10 and 0.05) at 293 K and 77 K. We find that there is only spin-spin relaxation time of lithium ions in solid phase, T₂= 87μs, which obeys Gaussian decay law at 77 K. At. room temperature all lithium ions devide into two phases. T_2s of lithium ions in solid phase still obeys Gaussian law of decay, T_2s =127 μs, but T_2l of lithium ions in liquid phase obeys Lorentzian law. For three amorphous lithium-ionic conductor B₂O₃-0.7Li₂O-0.7LiCl-xAl₂O₃ (x = 0.15, 0.10 and 0.05), T_2l of lithium ions in liquid phase increases rapidly, i.e. their width of ⁷Li NMR absorption line becomes much narrower at about 401°,388°and 381℃ respectively. Hence the physical picture of interfacial effect between amorphous matrix and the crystallites is again confirmed.