The dielectric behaviour of polycrystalline Ba0.96Na0.04Ti0.96Nb0.04O3 solid solution

Purpose: The purpose of this work was to measure and investigate dielectric properties of new material, polycrystalline solid solution Ba0.96Na0.04Ti0.96Nb0.04O3 (BNTN4) within the temperature range 153 K-473 K. Design/methodology/approach: The dielectric spectroscopy method has been applied to measure dielectric and electric parameters within the frequencies from 20 Hz to 1 MHz. Findings: The dielectric permittivity (&epsilon') dependence on temperature (T) within the range of 473 K-225 K consist of two components: the reversly proportional one and the second one in the form of small local, transient peak at about 400 K. The global maximum is frequency dependent and above &sim 400 K along the T decrease, the dispersion of &epsilon' is initiated and low frequency dispersion of &epsilon' prevails below 250 K. Energy losses measure (&epsilon"), correlated with &epsilon'(T), is generally shifted towards lower T values. Its frequency dependence undergoes inversion which develops with T decrease and is initiated at about 370 K. The whole temperature induced phase transition turned out to be of relaxor kind and diffused process. The detailed analysis of this transition and its features was performed. Research limitations/implications: In order to determine the details of polycrystalline structure of BNTN4 new material for modelling of ferroelectric properties the precise X-ray diffraction measurements should be performed as function of T. The nature of ferroelectric - paraelectric (FE - PE) transition diffusive character will be studied by means of dielectric measurements within frequency range 1 MHz-1.8 GHz. Originality/value: The new kind of ferroelectric solid solution (BNTN4) was synthesized. The specific features of this material at low T range involves among others, the T-dependent dispersion of dielectric properties on low T side of broad &epsilon'(T) peak.