Dielectric and piezoelectric perfomance of lead-free ceramics of boron sodium gadolinate niobate at morphotropic phase boundary

Abstract

New lead-free piezoceramic nanocomposites of Boron Sodium Gadolinium Niobate (BNGN), with general formula (1[Formula: see text]B[Formula: see text]Na[Formula: see text]GdO[Formula: see text][Formula: see text]B[Formula: see text]Na[Formula: see text]NbO3, exhibiting a Morphotropic Phase Boundary (MPB), have been synthesized following hydrothermal method followed by solid state sintering. The occurrence of MPB at the composition with [Formula: see text], at which rhombohedral and monoclinic phases are found to coexist, has been confirmed using powder XRD. This accounts for the occurrence of large remnant polarization when the sintered ceramic pellets are subjected to electric poling at 2KV/mm. Uniform microstructure of various compositions is confirmed by SEM imaging. Dielectric and piezoelectric properties of the samples are found to be comparable to those of commercial grade PZT. At the MPB, the d[Formula: see text] coefficient is found to be 556 pC/N, which is close to that of commercial grade PZT, which makes BNGN a promising material to substitute lead containing PZT in the near future.