Reactive template grain growth of BiFeO₃-PbTiO₃ by using Bi₄Ti₃O₁₂, PbBi₄Ti ₄O₁₅ and SrTiO₃ as templates

Bismuth ferrite exhibits multiferroic properties at room temperature. It is a perovskite with a rhombohedrally distorted lattice and has a ferroelectric Curie point of 836°C. Lead titanate is a tetragonal perovskite with a ferroelectric Curie point of 490°C. The solid solution between bismuth ferrite and lead titanate xBiFeO₃-(1-x)PbTiO₃, or BFPT, possesses a morphotropic phase boundary (MPB) between the rhombohedral and tetragonal forms at x=0.7. It is of interest to investigate the influence of field-driven rhombohedral-tetragonal phase transitions across the MPB, to determine whether correctly oriented BFPT can provide both giant piezoelectric properties and significant magnetoelectric coupling. Here, we used the reactive template grain growth (RTGG) technique to prepare crystallographically textured BFPT ceramics. Template grain growth (TGG) utilizes an oriented template as a seed to improve and increase preferred directional growth within a polycrystalline matrix. In this example, Bi₄Ti₃O ₁₂, PbBi₄Ti₄O₁₅ and SrTiO ₃ have been used separately as templates during the process of BFPT preparation. The samples were characterized using X-ray diffraction, using both conventional and synchrotron sources and scanning electron microscopy. The results show that PbBi₄Ti₄O₁₅ is the most effective template providing a level of texture I_TEX = 1.80, with the tetragonal (001) reflection orientated along the cast direction. The limited penetration depth of laboratory XRD renders it insufficient to characterise the texture of these materials.