Abstract

The electrical conductivity σ of a series of multidomain LiNbO₃:Zn,Mg crystals prepared via direct doping in the composition ranges ~1 ± 0.02 mol % MgO and ~2.8–4.6 mol % ZnO has been shown to undergo a sharp increase at T* ≈ 800 K, accompanied by anomalies in temperature dependences of their dielectric permittivity, ε(T). The largest increase in their static bulk conductivity near T* has been observed in a narrow composition range (≈1 ± 0.02 mol % MgО and ≈3.9–4.3 mol % ZnO). Above T*, the LiNbO₃:Zn,Mg crystals have an activation enthalpy for ionic conduction (H_a ≈ 1.76–2.15 eV) and enthalpy of transport (H_m ≈ 1.66–2.06 eV) unusually high for cation conductors, whereas below T* both quantities are characteristic of Li⁺ ion conduction in LiNbO₃ crystals (Н_а ≈ 1.15–1.35 eV and Н_m ≈ 1.0–1.1 eV). The anomalous increase in H_a and H_m is caused by the formation of associated vacancies (divacancies) and correlated pair hopping of Li⁺ ions above T*.

中文翻译：

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450-900 K温度范围内直接掺杂的LiNbO 3：Zn，Mg晶体的电导率和介电常数

摘要

通过直接掺杂制备的一系列多畴LiNbO ₃：Zn，Mg晶体的电导率σ在〜1±0.02 mol％MgO和〜2.8-4.6 mol％ZnO范围内已显示出在T *时急剧增加。≈800 K，伴随着介电常数ε（T）的温度依赖性异常。在狭窄的组成范围内（≈1±0.02 mol％MgО和≈3.9-4.3mol％ZnO）观察到它们在T *附近的静态体积电导率的最大增加。以上Ť *，铌酸锂₃：锌，镁晶体具有离子导电的活化焓（ħ_一个≈1.76-2.15 EV）和运输的焓（ħ_米 ≈1.66-2.06 eV）的异常高为阳离子导体，而低于Ť *两个量为Li的特性⁺在铌酸锂离子传导₃晶体（Н _а ≈1.15-1.35 eV和Н_米≈1.0-1.1电子伏特）。H _a和H _m的异常增加是由相关空位（微晶）的形成以及高于T *的Li ⁺离子的相关成对跳跃引起的。