Optical, electrical, and crystal structure study of BaZr0.01Ti0.99O3 ceramics modified with Gd3+ and Y3+ rare-earth ions

Abstract

Ceramics with compositions Ba0.95Gd0.034Ti0.99Zr0.01O3 (BGdZT) and Ba0.95Y0.034Ti0.99Zr0.01O3 (BYZT) were prepared using the solid-state reaction method. The single tetragonal phase (space group P4mm) of BGdZT and BYZT ceramics is verified by analyzing X-ray spectra using the Rietveld method. The analysis of the tolerance factor (t) reveals an order-disorder phase transition in the tetragonal structure, resulting from the displacement of Ti4+/Zr4+ along the c-axis. A significant correlation is observed between the tolerance factor (t) and the phase transition temperature (Tc), as well as between the band gap of optical measurements and the degree of displacement of Ti4+/Zr4+ along the c-axis. The analysis of high-temperature electrical properties indicates that the conduction mechanism in both studied materials is a correlated barrier hopping (CBH) model, and electrical conductivity improves with increasing densification. The non-Debye behavior is confirmed by the curves of the M′′ vs.ƒ(Hz). The combination of M′′/M′′max and Z′′/Z′′max traces confirms the type of short-range charge carrier mobility.