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Novel multiferroic (Pb1 − 3x/2Ndx)(Ti0.98 − yFeyMn0.02)O3 ceramics with coexisting ferroelectricity and ferromagnetism at ambient temperature

Research paper by F. Craciun, M. Cernea, V. Fruth, M. Zaharescu, I. Atkinson, N. Stanica, L.C. Tanase, L. Diamandescu, A. Iuga, C. Galassi

Indexed on: 16 Aug '16Published on: 16 Aug '16Published in: Materials & Design



Abstract

We report the evolution of structural, dielectric, ferroelectric and ferromagnetic properties in novel (Pb1 − 3x/2Ndx)(Ti0.98 − yFeyMn0.02)O3 perovskite ceramics(x = 0.08, 0 < y < 0.05). We found room-temperature ferroelectric polarization and ferromagnetism for higher amount of iron ions(y ≥ 0.04). The paraelectric-ferroelectric phase transition occurred between 650 and 670 K for 0 ≤ y ≤ 0.05. Ferromagnetic hysteresis was measured at different temperatures on samples with y ≥ 0.04. Detailed structural analysis evidenced the variation of unit cell parameters with y increasing, confirming the substitution of the iron element in the lattice. 57Fe Mössbauer spectroscopy evidenced that iron ions occupy Ti positions in the perovskite lattice, with the oxidation state Fe3 + and two coordination types. X-ray photoelectron spectroscopy confirmed the presence of iron only as Fe3 + and, moreover, evidenced the presence of a substantial amount of Ti3 + ions in the structure. The presence of both Fe3 + (spin 5/2) in different coordinations as well as Ti3 + (spin 1/2) magnetic ions in B-site positions drives the occurrence of magnetic properties from low temperature to above room temperature, through superexchange Fe3 +-O-Fe3 +, Fe3 +-O-Ti3 + and Ti3 +-O-Ti3 + interactions. The finding of coexistent ferroelectric and ferromagnetic properties in these compounds ground the route to facile synthesis of multiferroics by simply doping a classical perovskite ferroelectric material like PbTiO3 with an adequate amount of transition magnetic ions.

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