Structural investigation of a novel perovskite-based lead-free ceramics: xBiScO3−(1−x)BaTiO3

A full structural investigation was carried out on novel lead-free piezoelectric solid solutions of xBiScO3−(1−x)BaTiO3 (BS-BT) between x=0.0 and 0.35 utilizing x-ray and neutron powder diffraction. This particular system demonstrated an extended tetragonal-pseudocubic phase boundary at room temperature in the region 0.05≤x≤0.20. Rietveld refinements were performed on the neutron powder diffraction data to obtain detailed crystallographic information across the phase diagram of this binary system. The best model to describe the phase boundary was found to be a mixture of tetragonal (P4mm) and strongly pseudocubic rhombohedral (R3m) phases. Non-ambient x-ray diffraction patterns were collected in the temperature range of −253 to 325 °C to elucidate the effect of incorporation of BiScO3 on the temperature-dependent structural phase transitions of BaTiO3. Interestingly, the BS-BT system for x≥0.05 demonstrated only one structural phase transition, which is the ferroelectric to paraelectric phase transition, suppressing the other two low temperature phase transitions. High-temperature dielectric properties were also studied in order to examine the physical properties of the ceramics.