Microwave-Hydrothermal Synthesis of Nb-doped BaTiO₃ Nanoparticles under Various Conditions

Abstract

UDC 544.463:544.526.5

Tetragonal BaTiO₃ powders were synthesized by the microwave-hydrothermal (MH) method. The effects of the reaction time and temperature on the MH synthesis were investigated. Typical experiments were performed with a solid state reaction for the system BaTiO₃+Nb₂O₃ at a high temperature. In the MH method, at a shorter time and lower temperature, the rate of the formation of tetragonal BaTiO₃ and of the growth of particles went down substantially. The microwave heating can be very fast and uniform through a self-heating process that results from the direct absorption of the microwave energy in the reaction mixture. The synthesis of Nb-doped BaTiO₃ has been investigated under MH conditions in the temperature range of 120–180°C for 1–3 hours using C₁₆H₃₆O₄Ti, BaH₂O₂·8H₂O, and NbCl₅ as Ba, Ti and Nb sources, respectively. In the phase evolution studies, the X-ray diffraction measurements and Raman spectroscopy were employed. The Transmission Electron Microscope and the Field Emission Scanning Electron Microscopy images were taken for the detailed analysis of the grain size, surface, and morphology. The MH method was applied for the synthesis of Nb-doped BaTiO₃ via provided advantages of the fast crystallization and decreased crystallite size. The nucleation rate should have been high because of a high heating rate in microwave heating processes.

Keywords: ceramics, chemical synthesis, microwave-hydrothermal synthesis, crystal structure, perovskites.