Optimization of Pb content in enhancing ferroelectricity and shifting the Tc of BaTiO3 to a higher temperature

Abstract

Sol-gel prepared homogeneous Ba1 − xPbxTiO3 ceramics reveal elongation along the c-axis and contraction along the a-axis, thereby increasing the tetragonality (c/a ratio) with Pb doping. Raman spectral shape changes with composition and hardening and softening of vibrational modes are discussed and correlated to the structure and oxygen content. A new differential mode (in BaTiO3) predicted theoretically between two A1 Raman modes is experimentally detected at ∼71 cm−1. Tetragonal to cubic phase transition temperature (Tc) increases linearly with an increase in Pb content. Hence, appropriate Pb addition enhances Tc and thereby retains ferroelectricity until it reaches a higher temperature in the ceramics. Ferroelectricity in the solid solution was confirmed to enhance with an increase in Pb content from field-dependent polarization measurements. With Pb content, more than 50%, ferroelectric properties of the ceramics degrade and the materials become lossy due to the presence of O-defects originating from Pb-loss. This work provides an insight into how two well-known ferroelectric properties can be mixed to enhance its properties.