Phase transitions and magnetoelectroelastic instabilities in Pb(Fe1/2Nb1/2)O3 multiferroic ceramics

Abstract Magnetoelectric coupling can be observed in multiferroic materials in the regions where magnetic and ferroelectric ordering coexist and in many cases is mediated via lattice strain. Pb(Fe 1/2 Nb 1/2 )O 3 (PFN) is a well-known multiferroic, presenting ferroelectric ordering (below T C = 380 K) and a Neel temperature (antiferromagnetic ordering) T N = 143 K. However, recent experimental results suggest that PFN can display ferromagnetic ordering at higher temperatures and a still unclear sequence of phase transitions. In this work, high-density PFN ceramics were prepared by a conventional ceramic method. Dielectric, magnetic and anelastic responses were measured as a function of temperature. The experimental results present complementary evidence of anomalies (additional to those which can be directly associated with the reported transitions at T C and T N ) which cold be associated with a structural phase transition ( T ∼ 315 K), an antiferromagnetic–ferromagnetic phase transition (110 K) and magnetoelectroelastic instabilities around 250 K.