Synthesis of La and Nb doped PZT powder by the gel-combustion method

摘要

Lanthanum and niobium doped PZT with composition (Pb_(0.93)La_(o.07))[(Zr__(0.60)Ti_(0.40))]_(0.9825)Nb_(0.0175)O_3 (PZTLN) was prepared by the gel-combustion method. A precursor sol was obtained from lead nitrate, zirconyl nitrate, lanthanum oxide, peroxo-citrato-niobium and a peroxo-citrate complex of titanium isopropoxide as starting precursors. Various molar ratios of citrateitrate (CA/NO_3~ = 1.3, 0.36 and 0.09) were used to prepare very fine powders of PZTLN. The gels resulting from these sols were transformed into powders by an auto-combustion process at si400 deg C. The powders consisted of rhombohedral PZT (PbZr_(0.6)oTi_(0.40)O_3), pyrochlore (Pb_2Ti_2O_6) and lead carbonate (Pb_O.CO_3) phases. The pure rhombohedral phase is found in PZTLN pellets sintered at 1100 deg C for all citrateitrate ratios. Titanium and niobium precursors were modified with peroxo radicals. During the gel-combustion reaction, the temperature of the gel increases, leading to lead evaporation. The loss of lead as well as the particle size increases as the CA/NO_3 ratio decreases. The smallest grained powder (about 50 nm) was obtained with the ratio CA/NO_3 equal to 0.09.