Ferroelectric Lead metaniobate and its solid solutions: Solid state synthesis and characterization

Orthorhombic Lead metaniobate (PbNb₂O₆) exhibits ferroelectric properties and has a Curie temperature, T_C of 570°C. This work reports on investigations made on ferroelectric Lead metaniobate, (PN) and its solid solutions with bismuth and titanium Pb_(1-X)Bi_X(Nb_(1-X/2)Ti_X/2)2O₆, (PBTN), bismuth and sodium Pb_(1-X)Bi_X/2Na_X/2Nb₂O₆, (PBNN), bismuth and potassium Pb_(1-X)Bi_X/2K_X/2Nb₂O₆,(PBKN), and calcium and titanium (1-x)PbNb₂O₆-xCaTiO₂, (PCTN). The ferroelectric polymorph was obtained for all the solid solutions without quenching, and the optimized sintering temperature was reduced with increasing substitution level except in the system PCTN. The lattice parameters of the solid solutions were found to systematically vary with composition. Curie temperature was reduced with increasing substitution level in all the series. Piezoelectric charge constant d33 increases with composition of the solid solutions.