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摘要: 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T2s=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T2l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。
Abstract: 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. T2s of lithium ions in solid phase still obeys Gaussian law of decay, T2s =127 μs, but T2l 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), T2l 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.
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