Effect of nonstoichiometry on the microstructure and dielectric properties of strontium titanate ceramics

• Published in: Journal of the European Ceramic Society 2005, Vol.25 (12), p.2769-2772
• Main Authors: Tkach, A., Vilarinho, P.M., Senos, A.M.R., Kholkin, A.L.
• Format: Article
• Language: English
• Subjects: Applied sciences; Building materials. Ceramics. Glasses; Capacitors; Ceramic industries; Chemical industry and chemicals; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Dielectric loss and relaxation; Dielectric properties; Dielectric properties of solids and liquids; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Electron microscopy; Electrotechnical and electronic ceramics; Exact sciences and technology; Permittivity (dielectric function); Physics; SrTiO 3; Technical ceramics
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/j.jeurceramsoc.2005.03.137

Nonstoichiometric strontium titanate (ST) ceramics with precisely controlled Sr/Ti ratio of 0.997–1.02 were synthesised by solid state reaction. Structural properties and microstructure development was examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The dielectric properties were evaluated as a function of the temperature and frequency in the radio frequency range. The grain size was found to decrease dramatically with increasing Sr/Ti ratio > 1. The variation of Sr/Ti ratio has only weak effect on the quantum paraelectric behaviour of ST without any dielectric anomaly observed. The TiO 2 excess promotes the increase of the dielectric permittivity values with loss factor similar to stoichiometric ST. Sr 1.01TiO 3.01 composition exhibits much lower loss, while the dielectric permittivity is somewhat below the values for stoichiometric ST ceramics.