Effect of CoO additive on structure and electrical properties of (Na0.5Bi0.5)0.93Ba0.07TiO3 ceramics prepared by the citrate method

Abstract (Na0.5Bi0.5)0.93Ba0.07TiO3 ceramics with added 0–0.8 wt.% CoO were prepared by a citrate method and the influence of the CoO additive on the structure and electrical properties of the ceramics was investigated. All the specimens maintained a rhombohedral–tetragonal phase coexistence in crystal structure and the addition of CoO caused a remarkably promoted grain growth. Adding CoO led to a disappearance of the response in the dielectric constant (er) to the ferroelectric–antiferroelectric transition and increased the diffuseness of the dielectric constant peak around 230 °C. Polarization–electric field hysteresis loops at varied temperatures revealed that adding CoO served to increase the depolarization temperature (Td). The addition of CoO tailored the dielectric, piezoelectric and ferroelectric properties at room temperature basically following a hard doped effect. The specimen with 0.8 wt.% CoO added showed a low dissipation factor (tanδ) of 0.8% and a high mechanical quality factor (Qm) of 297 while retaining a piezoelectric constant (d33) of 137 pC N−1.