Reactive template grain growth of BiFeO3-PbTiO3 by using Bi4Ti3O12, PbBi4Ti4O15 and SrTiO3 as templates

摘要

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, Bi4Ti3O12, PbBi4Ti4O15 and SrTiO3 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 ITEX = 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.