Low-temperature neutron diffraction and magnetic studies on the magnetoelectric multiferroic Pb(Fe0.534Nb0.4W0.066)O3

Abstract

We report detailed low-temperature magnetic and neutron diffraction studies on 0.8 Pb(Fe0.5Nb0.5)O3–0.2 Pb(Fe0.67W0.33)O3 which is written as Pb(Fe0.534Nb0.4W0.066)O3 (PFWN) in the general form. Magnetic susceptibility measurement data show that PFN exhibits antiferromagnetic to paramagnetic transition (T N) around 155 K (Matteppanavar et al. in J Mater Sci 50:4980–4993. doi:10.1007/s10853-015-9046-5, 2015). In the present solid solution, the magnetic susceptibility (χ) shows Neel temperature enhanced up to around 187 K. Temperature-dependent neutron diffraction studies well support the tuning up of T N from 155 to 187 K. On decreasing the temperature, for T < T N (T N = 187 K), an extra peak grows at scattering vector Q = 1.35 A−1, which indicates the onset of antiferromagnetic ordering. The observed magnetic structure is G-type antiferromagnetic with the propagation vector, k = [0.25, 0.5, 0.5]. The refined monoclinic lattice parameters (a, b and c), angle (β), unit cell volume, derivative of unit cell volume, magnetic moments and integrated intensity of magnetic peak (111) show anomaly around the T N, which is a manifestation of spin–lattice coupling. Also, the lattice parameters (a, b and c) and unit cell volume exhibit negative thermal expansion below T N and a large thermal expansion above T N.