The effect of quenching on semiconductive properties and magnetic phase transition temperature of multiferroic Pb(Fe1/2Nb1/2)O3 ceramics

Neel temperature of Pb(Fe1/2Nb1/2)O-3 ceramics sintered at 1120 degrees C and quenched to room temperature was revealed to be 25K higher than that of the same ceramics slowly cooled at a rate of 50K/h. A small singlet component, typical for compositionally ordered perovskites, is present in the room-temperature Mossbauer spectrum of the slowly cooled sample. It proves that the quenched sample is more compositionally disordered than the slowly-cooled one. Substantially higher room-temperature resistivity values and positive temperature coefficient of resistivity of the slowly cooled sample are attributed to the formation of the grain-boundary potential barriers due to oxidation during slow cooling.