Phase transition and relaxor nature of BaTiO3 ceramics induced by Li/Ga co-doping

The structure, dielectric, and ferroelectric properties of Li/Ga-modified BaTiO3 ceramics were investigated and analyzed. As the Li/Ga doping content x >= 0.02, an evident structure transformation occurred from the ferro-electric tetragonal to hexagonal phase due to the Li/Ga dopants replacing Ti-sites. Rietveld refinement results proved an increased content of hexagonal phase with the co-doping. The dielectric measurement results showed that an obvious transition from a typical ferroelectric behavior for the undoped samples to a highly diffusive phase transition (DPT) behavior for the Li/Ga-modified BT ceramics. The diffuseness coefficient gamma was found to increase with an increase in the Li/Ga content. The relaxor-like phenomenon can be attributed to the disruption of long-range ferroelectric order and the structure evolution of from tetragonal to hexagonal phase. The slim and thin-waisted hysteresis loops were observed for x = 0.01 and x = 0.02, which may originate from the defect dipoles and relaxor-like behavior.