Synthesis, characterization and electrical properties of sol–gel derived 0.63Bi(Mg1/2Ti1/2)O3–0.37PbTiO3 high-Tc piezoelectric ceramics

The nano-scaled powders of a high Curie temperature piezoelectric system with a composition of 0.63Bi(Mg1/2Ti1/2)O3–0.37PbTiO3 (0.63BMT–0.37PT) have been synthesized via a citrate sol–gel method. The thermal decomposition process of the as-prepared xerogel was investigated through the thermo-gravitometry and differential scanning calorimetry. The lattice structure of the powders as the function of heat-treatment temperatures was explored by using X-ray diffraction, Fourier-transform infra-red and Raman spectra. The results indicated that the transparent gel could be obtained via the chelate reaction of citric acid with ethylene glycol and ethanolamine assist. Gels can be transformed into crystallite powders with a single-phase perovskite structure when heat-treated at 600 °C for 3 h, much lower than that of traditional solid-state reaction method. The sol–gel derived 0.63BMT–0.37PT ceramics sintered at 1020 °C exhibit excellent dielectric, ferroelectric and piezoelectric properties of Tc = 463 °C, image, tan δ = 0.063, Pr = 22.1 μC cm−2 and d33 = 230 pC N−1. Moreover, a small amount of Mn2+ doping could cause the reduced leakage current and slightly increased Tc values.