Electrical property of K2NiF4-type Ca2(Mn1−xNbx)O4

Tetragonal K2NiF4-type Ca2(Mn1−xNbx)O4 with the space group I41/acd was synthesized in the range 0.0 ≤ x ≤ 0.15. Ca2(Mn1−xNbx)O4 is an n-type semiconductor and exhibits the hopping conductivity in a small polaron model. The number of carriers (n) is ≈6.5 × 1026 m−3 (x = 0.0) and 2.3–2.5 × 1027 m−3 (x = 0.05–0.15). At 320 K, the hopping mobility (μh) is ≈2.2 × 10−9 m2·V−1·s−1 (x = 0.0) and 1.0–1.2 × 10−8 m2·V−1·s−1 (x = 0.05–0.15). The electrical conductivity is influenced by the Mn3+ ion content and the (Mn, Nb)-O distance.