Local heterogeneities and order-disorder: An approach to tailor BaTi1-xZrxO3 ceramics properties

Abstract

Zirconium-doped Barium Titanate with the formula, BaTi1-xZrxO3 (BZT) for 0 <= x <= 0.08 had been prepared by the modified solid-state reaction route. X-ray diffraction patterns (XRD) and structural refinement showed the formation of single and double phases for pure and Zr-substituted barium titanate, respectively. Pure barium titanate (BT) was found in the tetragonal phase. BZT-3 and BZT-5 had a mixture of tetragonal and orthorhombic phases. A mixture of orthorhombic and rhombohedral phases was present in BZT-8. The Raman analysis confirmed the existence of two oxygen octahedra of Ti and Zr for Zr-doped BT. The FESEM micrograph exhibited an increase in average grain size with Zr content. The temperature-dependent dielectric studies showed single-phase transitions for BT, two-phase transitions for BZT-3 and BZT-5, and three-phase transitions for BZT-8. XPS analysis confirmed the presence of undercoordinated Ti3+ions. The maximum dielectric constant of 5731 was obtained for BZT-3, which decreased linearly afterward. The maximum remanent polarization = 8.287 mu C/cm2 was found for BZT-3. The energy storage efficiency >= 50.10 % makes all the compositions suitable for high energy density capacitors. Due to the presence of 90.63 % of the orthorhombic phase in BZT-5, the highest d33 = 164 pC/N was obtained. The UV-visible spectroscopy showed the signature of p-d and d-d transitions present in the ceramics due to disordering. The direct optical bandgap increased with the rise in Zr content.