Synthesis and electrical properties of ordered perovskite oxide Cd3−x−yCuxAyTeO6 (A = Li, Na; 0.00 ≤ x, y ≤ 0.15)

Polycrystalline Cd3−x−yCuxAyTeO6 (A = Li, Na) samples were prepared by solid-state reaction, and their crystal structure and electrical properties were investigated. In Cd3−xCuxTeO6 and Cd3−yAyTeO6 (A = Li, Na), the maxim solubility of x and y was 0.15 and 0.15 for A = Li, 0.05 for A = Na, respectively. For co-substituted samples Cd2.9−yCu0.1LiyTeO6 and Cd2.9−yCu0.1NayTeO6, the maxim solubility of x was the same as single substitution above-mentioned. The alkali-metal substituted samples Cd3−yAyTeO6 (A = Li, Na) showed a negative Seebeck coefficient, which indicates that the major conduction carriers are electron. On the other hand, the co-substituted samples Cd2.9−yCu0.1AyTeO6 (A = Li, Na) represented a positive Seebeck coefficient, and major conduction carriers were hole through substitution by copper ions.