Dielectric and piezoelectric properties of La doped lead zinc niobate–lead zirconium titanate ceramics prepared from mechano-chemically activated powders

Lead zinc niobate–lead zirconium titanate, 0.3Pb(Zn1/3Nb2/3)O3–0.7Pb(Zr0.51Ti0.49)O3 (PZN–PZT), ceramics doped with different amounts of lanthanum (La) were prepared by mechano-chemical alloying (MCA) method accompanied by sintering. The results of X-ray diffraction suggest that all the ceramics crystallize into a single-phase pervoskite structure. The SEM analysis of the ceramic samples reveals a dense microstructure with homogeneous distribution of grains. The bulk density of the ceramics increases with the increase of La content. The effects of the La doping on the dielectric and piezoelectric properties of the ceramics were systematically examined. An increase in La concentration causes the Curie temperature (Tc) to decrease and the phase transition to become more diffused. The piezoelectric charge co-efficient (d33) and electromechanical coupling constant (kp) show improvement with the increase of La doping level in the ceramic system. The d33, kp and percentage strain of the 3 mol%-La doped PZN–PZT ceramic were observed to be 575 pC/N, 64 and 22%, respectively.