Magnetic ordering and instability investigation of multiferroic Pb(Fe2/3W1/3)O3 ceramics by microwave dielectric spectroscopy

The microwave dielectric and magnetic properties of Pb(Fe2/3W1/3)O3 multiferroic ceramics were investigated. A dielectric dispersion occurring in the frequency range 100 MHz–3 GHz and in a broad temperature range showed itself to be a powerful tool to detect magnetostrictive effects. The experimental results revealed the following remarkable features: the temperature dependence of f R (characteristic frequency) and the dielectric strength Δ ε (characteristic of the dispersion) enabled us to identify not only the para–ferroelectric ( T C ≈ 180  K) but also the para–antiferromagnetic ( T N ≈ 340  K) phase transitions, while magnetic measurements revealed the para–antiferromagnetic ordering and a weak superexchange interaction ( T N 2 ∼ 15  K). Additionally, both characterizations confirmed the existence of structural or magnetic instabilities around 250 K.