Enhanced ferroelectricity in PLZT ceramic by precise La-doping, minimizing pyrochlore phase and lead loss

A comparative study correlating structure and ferroelectricity in La-doped PbZr0.52Ti0.48O3 [PZT] for La = 0-4% has been carried out. Due to increase in tetragonality, 2% La doped PZT shows highest polarization. A modified low cost, but highly proficient method of Double Atmospheric Layer Protected Sintering (DALPS) has been developed to sinter pyrochlore free 2% La-doped PbZr0.52Ti0.48O3 prepared by a modified sol-gel synthesis. The DALPS method enhances the remnant polarization by 29% and dielectric constant by 23% with around 50% decrease in dielectric loss tangent. The effectiveness of DALPS in preventing lead loss is confirmed by EDS analysis. As a result of the employment of the modified sol-gel synthesis and DALPS, a remnant polarization value as high as 49.25 mu C cm(-2) with nearly ideal hysteresis loop is observed in bulk Pb0.97La0.02Zr0.52Ti0.48O3. The squareness factor of the P-E loop is 99.7% of an ideal value. The Positive Up Negative Down (PUND) measurement shows enhanced remnants with polarizations: the values of + dP(r) and -dP(r) are 112 and 117 mu C cm(-2) respectively. The dielectric loss is also sufficiently low and at room temperature and the value of tan delta is 0.016 with dielectric constant of 1369 at 1 kHz.