Ceramics-Silikáty 48 (4) 180-184 (2004)

CaTiO₃ RELATED MATERIALS FOR RESONATORS

L. TaIbi - Benziada, A. Mezroua, R. Von Der Mühll

Ceramics of Ca_0.95M_0.05(Ti_0.95Li_0.05)O_2.85F_0.15 (M = Ca, Sr, Pb) are prepared from mixtures of CaTiO₃, MF₂ and LiF powders by sintering at 950°C for 4 hours in free-air. The samples are investigated by X-ray diffraction, scanning electron microscopy, differential scanning calorimetry and dielectric measurements. The phase transitions of pure CaTiO₃ are strongly influenced by the incorporation of the fluoride mixture MF₂ + LiF into the host lattice whereas the orthorhombic symmetry at room temperature is not at all affected by the chemical substitutions Ca-M, Ti-Li and O-F. The dielectric permittivity e'r and losses tand are slightly dependent of temperature between 20°C and 200°C. At room temperature, e'r is stable over a large frequency range with tand < 1%. The Ca_0.95M_0.05(Ti_0.95Li_0.05)O_2.85F_0.15 (M = Ca, Sr, Pb) oxyfluorides are promising materials to manufacture resonators.

Keywords: CaTiO₃, Oxyfluorides, Phase transitions, Dielectric characteristics