Dielectric properties of Mg-modified Pb(NbMo)O3 system ceramics

The polycrystalline samples of magnesium (Mg)-modified Pb(Nb3/4Mo1/4)O3 (PNM) (i.e., (Pb1 − zMgz)0.375(Nb0.75Mo0.25)O3, where z = 0.0, 0.03, 0.05, 0.07) were synthesized by a high-temperature solid-solution reaction technique. Some aspects of crystal structure of the compounds at room temperature were studied using an X-ray diffraction (XRD) technique. Studies of dielectric properties (dielectric constant (ɛ) and tangent loss (tan δ)) both as a function of frequency (100 Hz to 100 kHz) and temperatures (290–450 K) exhibit dielectric anomaly in the range of 365–391 K suggesting a possible ferroelectric–paraelectric phase transition in the compounds. The transition temperature increases on increasing Mg content in PNM. The activation energy (Ea) calculated from the plot of ac conductivity versus inverse of absolute temperature was found to be 0.15 eV.