Ionic conductivity of congruently melting Ca0.6Sr0.4F2 and Ca1 − x − ySryRxF2 + x (R = La, Ce, Pr, Nd) single crystals with fluorite structure

• Published in: Crystallography reports 2008-03, Vol.53 (2), p.271-277
• Main Authors: Sorokin, N. I., Karimov, D. N., Krivandina, E. A., Zhmurova, Z. I., Komar’kova, O. N.
• Format: Article
• Language: English
• Subjects: Crystallography and Scattering Methods; Physical Properties of Crystals; Physics; Physics and Astronomy
• ISSN: 1063-7745; 1562-689X
• DOI: 10.1134/S1063774508020168

Single crystals of congruently melting compositions of the Ca 0.6 Sr 0.4 F 2 and Ca 1 − x − y Sr y R x F 2 + x ( R = La, Ce, Pr, Nd; x = 0.16–0.21; y = 0.07–0.16) solid solutions with fluorite structure have been grown by the Bridgman-Stockbarger method. Their electrical properties have been investigated in the range from 473 to 823 K, and it is shown that they are ionic conductors. For Ca 0.6 Sr 0.4 F 2 crystals, the ionic conductivity σ = 2 × 10 −6 S/cm at 673 K, and the ion transport activation energy E a = 1.1 eV. For Ca 0.77 Sr 0.07 La 0.16 F 2.16 , Ca 0.70 Sr 0.11 Ce 0.19 F 2.19 , Ca 0.65 Sr 0.15 Pr 0.20 F 2.20 , and Ca 0.58 Sr 0.21 Nd 0.21 F 2.21 crystals, the values of σ lie in the range from 9 × 10 −7 to 2 × 10 −6 S/cm at 500 K, and the activation energy E a is 0.88–0.93 eV. The concentration and mobility of ionic charge carriers in Ca 1 − x − y Sr y R x F 2 + x crystals have been calculated.