Electrical property of cubic perovskite-type Sr(Mn1-xNbx)O3 in Mn-rich region

Cubic perovskite-type Sr(Mn1-xNbx)O-3 (0.03 less than or equal to x less than or equal to 0.2) was synthesized by a standard ceramic technique. The cell constant increased linearly with increasing x. Sr (Mn0.97Nb0.03)O-3 (x = 0.03) exhibited a metal-insulator transition at ca. 390 K, whereas Sr (Mn1-xNbx)O-3 (0.05 less than or equal to x less than or equal to 0.2) was an n-type semiconductor in a temperature range of 80-773 K. From the magnetic measurement, it is obvious that the metal-insulator transition was caused by the change in the spin state of the Mn3+ ion. The Seebeck coefficient of Sr (Mn1-xNbx)O-3 (0.03 less than or equal to x less than or equal to 0.2) was negative and showed no significant difference in the composition.