Laboratório de Materiais Vítreos, Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, 13565-905 São Carlos-SP, Brazil.
J Chem Phys. 2011 Dec 21;135(23):234504. doi: 10.1063/1.3666835.
Conductivity data of the xAgI(1 - x)AgPO(3) system (0 ≤ x ≤ 0.5) were collected in the liquid and glassy states. The difference in the dependence of ionic conductivity on temperature below and above their glass transition temperatures (T(g)) is interpreted by a discontinuity in the charge carrier's mobility mechanisms. Charge carrier displacement occurs through an activated mechanism below T(g) and through a Vogel-Fulcher-Tammann-Hesse mechanism above this temperature. Fitting conductivity data with the proposed model allows one to determine separately the enthalpies of charge carrier formation and migration. For the five investigated compositions, the enthalpy of charge carrier formation is found to decrease, with x, from 0.86 to 0.2 eV, while the migration enthalpy remains constant at ≈0.14 eV. Based on these values, the charge carrier mobility and concentration in the glassy state can then be calculated. Mobility values at room temperature (≈10(-4) cm(2) V(-1) s(-1)) do not vary significantly with the AgI content and are in good agreement with those previously measured by the Hall-effect technique. The observed increase in ionic conductivity with x would thus only be due to an increase in the effective charge carrier concentration. Considering AgI as a weak electrolyte, the change in the effective charge carrier concentration is justified and is correlated to the partial free energy of silver iodide forming a regular solution with AgPO(3).
收集了 xAgI(1-x)AgPO(3) 系统（0 ≤ x ≤ 0.5）在液态和玻璃态下的电导率数据。离子电导率对温度的依赖性低于和高于其玻璃化转变温度（T(g)）之间的差异，通过载流子迁移率机制的不连续性来解释。在 T(g)以下，载流子的位移通过激活机制发生，而在高于该温度时，则通过 Vogel-Fulcher-Tammann-Hesse 机制发生。用提出的模型拟合电导率数据，可以分别确定载流子形成和迁移的焓。对于所研究的五个组成部分，载流子形成焓随 x 从 0.86 eV 降低到 0.2 eV，而迁移焓在 ≈0.14 eV 处保持不变。基于这些值，可以计算出玻璃态下的载流子迁移率和浓度。室温下的迁移率值（≈10(-4) cm(2) V(-1) s(-1)）与 AgI 含量的变化不大，与之前通过 Hall 效应技术测量的值吻合较好。因此，离子电导率随 x 的增加仅归因于有效载流子浓度的增加。考虑到 AgI 是弱电解质，有效载流子浓度的变化是合理的，与银碘化物形成规则溶液的部分银碘化物的自由能变化有关。
