Investigation on dielectric response of PMN ceramics around paraelectric–ferroelectric diffuse phase transition

Abstract

The dielectric properties of relaxor ferroelectric lead magnesium niobate Pb(Mg_1/3Nb_2/3)O₃ (PMN) ceramics have been investigated. These studies were conducted taking into account the characterisations of the complex dielectric permittivity (real and imaginary parts) as a function of temperature and frequency in a wide interval. On the other hand, the dc 'bias' electrical field dependence of the real dielectric permittivity (C–V characterisations) has been analysed around the paraelectric–ferroelectric diffuse phase transition. Results obtained at room temperature (paraelectric phase) showed a typical behaviour of conventional dielectric materials, while measurements performed at 200 K (ferroelectric phase) evidenced an anomalous behaviour for frequencies up to 100 kHz. Such observed anomalies were characterised by two asymmetrical peaks on sweep-up and sweep-down, at − 15 and + 18 kV cm⁻¹ respectively.

Keywords:

• FERROELECTRICS
• RELAXORS
• PHASE TRANSITION
• PMN