Structural, optical and electrical properties of the microcrystalline structure of (Ba1-xY2x/3)(Zr0.20Ti0.80)O3 ceramics

Abstract Yttrium (Y3+) doped barium zirconate titanate, (Ba1-xY2x/3)(Zr0.20Ti0.80)O3; BYZT ceramics with varying x (0 = x ≤ 0.10) were prepared by the solid-state reaction method. These samples were analyzed by X-ray diffraction (XRD) and the XRD patterns were fitted using the Rietveld refinement. The local structural changes of the BYZT ceramics were investigated by synchrotron X-ray absorption spectroscopy. The results showed that an increase in the x content in the BYZT lattice structure significantly affected the phase transition behavior and the local structure around the Ti absorbing atoms, which corresponds with the phase transition from a tetragonal to a cubic structure. SEM images showed a uniform and highly dense microstructure with increasing x values. The optical band gap (Egap) values measured from the UV–visual diffuse reflectance spectra, showed a decrease from ~3.55 eV to ~2.90 eV with increasing values of x. The modified Curie-Weiss law showed that a normal ferroelectric phase transition is observed in the unmodified BZT ceramic and as the concentration of x increased, it induces diffuseness in the phase transition behavior. The largest dielectric constant (er = 13,200), the highest recoverable energy-storage density (Wrec = 1.76 J/cm3) with an excellent energy storage efficiency (η = 91%) under a lower electric field of 50 kV/cm and lowest dielectric loss (tanδ = 0.01) were found in the composition of Ba0.98Y0.01337Zr0.2Ti0.8O3 (x = 0.02 mol.%).