The crystal structure, microstructure, and dielectric properties of BaTi1-xSnxO3 (x = 0,0.05 and 0.1) ceramics sintered in different atmospheres (air and Ar)

Abstract

Due to specific dielectric and ferroelectric properties, functional ceramics based on barium titanate (BaTiO3) have found application in semiconductor industries. Appropriate electrical properties of barium titanate-based materials, such as magnitude of relative dielectric permittivity and the Curie temperature, could be achieved by varying the sintering conditions (which influenced ceramics’ microstructure) and/or by doping with various cations. Here, we investigated an influence of sintering atmosphere (air and argon) on the crystal structure, microstructure, and dielectric properties of barium titanate-stannate (BTS; BaTi1-xSnxO3) ceramics. The BTS powders (with x = 0, 0.05 and 0.1; denoted BT, BTS5 and BTS 10, respectively) were synthesized by solid-state reaction technique. In the following, the powders were uniaxially pressed (P = 240 MPa) into cylindrical compacts (Ø6 mm and h approx. 2 mm) and sintered in SETSYS TMA (Setaram Instrumentation, Caluire, France) by heating rate of 10 °/min up 1420 °C and with dwell time of 2 hours. To establish the influence of a sintering atmosphere two sets of experiments were performed: (1) in air, and (2) in Ar. During sintering, the shrinkage was recorded in axial (h) direction. The crystal structure of BTS ceramics were studied at room temperature by X-ray diffractometry and Raman spectroscopy. The microstructure and chemical (Ti/Sn) composition were examined by SEM–EDS methods. The electrical measurements were made in air, at 1 kHz using a Wayne Kerr Universal Bridge B224; the measurements were done in cooling, from 160 to 20 °C. A profound effect of argon atmosphere on the magnitude of relative dielectric permittivity of sintered BTS ceramics has been found.