Phase composition and spectroscopic characterization of barium titanate containing glass ceramics

Abstract

Glasses are synthesized in the system Na2O/BaO/TiO2/SiO2/B2O3/Al2O3 for different Na2O/Al2O3 ratios. X-ray photoelectron spectroscopy is utilized for the estimation of the valence states of titanium and the occurrence of solely Ti4+ is observed. The presence of bonds from the type Si-O-Al, Si-O-Si and Na-O-Si is detected in the glasses and it is concluded that the increasing alumina concentration leads to decreasing binding energy of the Al3+ ions in the glass. The glasses are subjected to thermal treatment in order to crystallize barium titanate with controllable size and in a high-volume fraction. The phase composition of the prepared glass ceramics is studied by X-ray diffraction. The precipitation of cubic barium titanate but also of other crystalline phases is observed while increasing alumina concentration and temperature. The structure of selected glass ceramics is investigated by infrared spectroscopy. The effect of crystallization on the main structural units and their change during the course of the crystallization is traced and the presence of the BaTiO3 phase is confirmed by the peak at about 570 cm−1. The peaks in the range of 1200–1500 cm−1 are with varying intensities and witness the occurrence of changing as number during the course of crystallization BO3 triangles containing non-bridging oxygen ions. The presence of BO4 and SiO4 tetrahedra in the glass ceramics is suggested from the peaks in the range of 800–1200 cm−1.