Temperature Dependence of the Li NMR Spectrum and Atomic Motion in LiNbO3
Temperature Dependence of the Li NMR Spectrum and Atomic Motion in LiNbO3
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LiNbO3 中 Li NMR 谱和原子运动的温度依赖性
DOI：
10.1063/1.1674513
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发表时间：
1970
影响因子：
4.4
通讯作者：
T. Halstead
中科院分区：
文献类型：
--
作者：
T. Halstead
在24 ~ 680°C的温度范围内测量了LiNbO3单晶的电四极耦合常数和Li核磁共振谱线宽，并根据Li的运动进行了解释。四极耦合常数的线性增加是不寻常的，假定是由于锂的各向异性振动。导出了温度变化的简单表达式，该表达式仅依赖于< z2 >−(x2 >)和∂4V /∂4z，其中< z2 >是Li的振动均方振幅，V是Li位点的晶体电势。∂4V /∂z4是通过离子晶格求和计算的。提出了四极耦合常数的线性增加是各向异性振动的光原子的特征。线宽数据的分析，假设Li原子扩散，得到D0 = 1.8 × 10−5m2sec−1和e = 1.62 eV。
Electric quadrupole coupling constants and linewidths of the Li NMR spectrum of a single crystal of LiNbO3 were measured at temperatures between 24 and 680°C and are interpreted in terms of the motion of Li. The linear increase of the quadrupole coupling constant is unusual and is assumed to be due to the anisotropic vibration of Li. A simple expression for the temperature variation is derived which depends only on 〈z2〉 − (x2〉 and ∂4V / ∂4z, where 〈z2〉 is a mean square amplitude of vibration of Li, and V is the crystal electric potential at a Li site. ∂4V / ∂z4 was computed by an ionic lattice summation. It is suggested that a linear increase of the quadrupole coupling constant is characteristic of a light atom that vibrates anisotropically. Analysis of the linewidth data, assuming that Li atoms diffuse, gives D0 = 1.8 × 10−5m2sec−1 and e = 1.62 eV.