ABSTRACT
Scientists all over the world are trying to develop piezoelectric materials that are free of toxic lead, because lead is hazardous to the environment. The most popular piezoelectric materials are piezoceramics of PZT (Lead Zirconate Titanate), which are used in a multitude of applications such as sensors, transducers and actuators. A new lead-free piezoceramic nano composite of Boron Sodium Gadolinium Niobate (BNGN) with the general formula (1-x) B0.5Na0.5GdO3-x-B0.5Na0.5NbO3, exhibit in Morphotropic phase boundary (MPB), have been synthezised following hydrothermal technique and solid-state sintering. The occurrence of MPB in the composition with x=0.55, at which rhombohedral and monoclinic phases are found to coexist, is confirmed by powder XRD technique. This accounts for the large remnant polarization in the sintered ceramic pellets, when they are subjected to electrical poling at high fields. Uniform microstructures of different components of the composite have been confirmed by SEM imaging. Dielectric spectroscopic and piezoelectric measurements have been carried out on the samples and are found to be comparable to those of commercial grade PZT. At the MPB composition the d33 coefficient of the composite is found to be 557pC/N, which is very close to that of commercial grade PZT, making lead-free BNGN a promising green material to substitute PZT for commercial applications in near future.
