Synthesis and characterization of monoclinic rare earth titanates RE 2Ti2O7 (RE = La, Pr, Nd), by a modified SHS method using inorganic activator

Abstract

The nano particles of phase pure rare earth titanates, synthesized by the SHS technique, get well sintered at lower temperatures compared to the compounds formed by the solid-state method. These dielectrics are highly stable and can be used in the microwave frequency range. We report here a modified SHS method to synthesize phase pure monoclinic RE2Ti2O7 at 350°C through the oxide/nitrate precursors using an inorganic compound, ammonium acetate, in place of the general type of organic activators such as urea, alanine etc. The nanopowders of La2Ti2O7, Pr2Ti2O7 and Nd2Ti 2O7 on heating exhibit an exothermic behaviour with a broad maxima in the range 267-284°C and become endothermic with maxima in the range 1043-1220°C; interestingly, the phase pure crystalline material is formed at the temperature of exothermic maxima, as confirmed by XRD. © Indian Academy of Sciences.