Inverse correlation between the ionic and thermal conductivities of single crystals of M1–xRxF2 + x (M = Ca, Ba; R—rare-earth element) fluorite solid solutions

Resumo

The logarithm of the 500-K fluoride ion conductivity of M_1–xR_xF_{2 + x} (M = Ca, Ba; R = rare-earth element) crystals is shown to be inversely correlated with their 100-K thermal conductivity: materials with high ionic conductivity have low thermal conductivity and vice versa. For groups of solid solutions containing defect clusters similar in structure, the correlation coefficient is about 0.85.