Effect of Pb/(Zr+Ti) molar ratio on the photovoltaic properties of lead zirconate-titanate ceramics

Lead zirconate-titanate ceramics having various Pbl (Zr+Ti) molal ratios ra nging from 0.90 to 1.01 and a fixed Zr/Ti molar ratio of 50/50 have been si ntered at 950-1250 degrees C for 2 h to investigate the change in photovolt aic properties, as well as their grain size dependence on ultraviolet irrad iation. The photovoltaic current increased abruptly when the molar ratio wa s less than 1.00, whereas the photovoltage gave scattered results and decre ased between the molar ratio of 0.99 and 1.00, which was caused by grain gr owth. The maximum output power discernibly increased confirming a net incre ase in photovoltaic efficiency. The grain size dependence of the photovolta ge revealed an opposite tendency in two samples with different molar ratios of 0.992 and 1.00. From these results, it is proposed that creating Pb vac ancies on the perovskite lattice is essential for the photovoltaic properti es of the samples. (C) 1999 Elsevier Science Limited. All rights reserved.