Hopping conductivity of distorted K2NiF4-type (Ca1+xNd1−x)CrO4

Orthorhombic distorted K2NiF4-type (Ca1+xNd1−x)CrO4 (0.00 ≤ x ≤ 0.15) was synthesized using a standard ceramic technique. The cell parameters (a and c) decreased, whereas the cell parameter (b) increased with the increase in x. The variation in the global instability index (GII) indicated that the crystal stability of (Ca1+xNd1−x)CrO4 was not influenced by the Cr4+ ion content. At all temperatures, the electrical conductivity (σ) of (Ca1+xNd1−x)CrO4 increased with the increase in x. (Ca1+xNd1−x)CrO4 was a p-type semiconductor and exhibited hopping conductivity in a small-polaron model in the temperature range of 290 K ≤ T ≤ 713 K. The Cr4+ ion acts as an acceptor, and the electron transfer through the Cr3+–O–Cr4+ path becomes active as a result of the Cr4+ ion content and the Cr–O(1) distance.

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