Integrated study of morphology, structure, and dielectric behavior in PZT-SASF ceramics at the morphotropic phase boundary

This research explores the synthesis and electrical characterization of SrF₂-modified lead zirconate titanate Pb_1-xSr_x[(Zr_0.43Ti_0.52) (Al_0.5Sb_0.5)_0.05]O_3-xF_2x, referred to as PZT-SASF ceramics. The synthesis was completed using solid-state methods, focusing on properties near the morphotropic phase boundary (MPB). The samples were analyzed using various laboratory techniques. Phase formation was studied using powder X-ray diffraction (XRD). This analysis revealed the coexistence of tetragonal and rhombohedral phases. Microstructural examination with scanning electron microscopy (SEM) showed a non-uniform distribution of large grains and some micro-sized pores. Impedance and electric modulus measurements were performed over a frequency range of 0.1 kHz–1 MHz and temperatures from 300 to 700 K. The results demonstrated the influence of grain structure on capacitive and resistive properties. The Nyquist plot revealed how grains contribute to resistance and capacitance. An appropriate electrical circuit was used for equivalent circuit analysis. Fitting procedures were implemented across all temperatures to determine grain resistance and capacitance values. Incorporating Sr²⁺ ions at the Pb-site and F⁻ ions at the O-site enhanced the dielectric constant at higher temperatures. Finally, the activation energy of the synthesized ceramics increased from 0.7 eV at x = 0.0 to 1.12 eV at x = 0.08 and then decreased to 0.97 eV at x = 0.1.