Low-temperature synthesis and characterization of complex perovskite (Ca0.61, Nd0.26)TiO3–(Nd0.55, Li0.35)TiO3 nanopowders and ceramics by sol–gel method

A sol–gel process was adopted to synthesize nanopowder with composition of (1 − x)(Ca0.61, Nd0.26)TiO3–x(Nd0.55, Li0.35)TiO3 which was used to prepare the dielectric ceramics. As x ≤ 0.8, pure solid solution phase with GdFeO3-type perovskite structure could be obtained by calcining the xerogels at 500 °C. At x = 0.6, the particle size calculated from the transmission electron micrograph of powder was in the range of 30–50 nm. Ceramics prepared by the nanoparticles at 1150 °C exhibited good dielectric properties with dielectric constant (ɛr) of 93.4, a Q × f value of 7115 GHz and τf value of 0 ppm/°C, which have great improvement in Q × f value and decreased the sintering temperature compared with the ceramics synthesized by solid-state method. HRTEM images showed superstructure, indicating that the solid solution phase with ordering crystal structure is helpful to the dielectric properties improvement.

Research highlights▶ Complex perovskite (1 − x)(Ca0.61, Nd0.26)TiO3–x(Nd0.55, Li0.35)TiO3 nanopowders and ceramics are synthesized by sol-gel method.▶ As x ≤ 0.8, pure solid solution phase with GdFeO3-type perovskite structure could be obtained by calcining the xerogels at 500 °C for 1 h. At x = 0.6, the particle size calculated by TEM was about 30–50 nm.▶ Dense ceramics synthesized by the nanoparticles could be achieved at low-temperature of 1150 °C due to the effect of small size nanoparticles.▶ ▶ The ceramics prepared by the nanopowder exhibited good dielectric properties with dielectric constant (ɛr) of 93.4, a Q × f value of 7115 GHz and τf value of 0 ppm/°C, which has higher Q × f value than the ceramics synthesized by solid-state method.