ملخص: Cold-pressed pellets were prepared from ATiO3-MF2-LiF mixtures (A=Sr, Ba; M=Ca, Sr, Pb) and air-fired at 1223 or 1273 K for 2 h. X-ray diffraction analysis were carried out to control the purity and to identify the different phases. Each sample was a perovskite single phase. Superlattice reflections with an orthorhombic symmetry were detected for SrTiO3 compounds whereas no significant change was observed in the structure of BaTiO3 materials. The ceramic microstructure was systematically characterized by scanning electron microscopy. Dielectric measurements were performed as a function of temperature (123 KTf9 Hz). At low frequencies, a diffuse ferroelectric phase transition occurred for (Ba, M)(Ti, Li)(O, F)3 ceramics. The room temperature frequency dependence of the complex permittivity has shown a resonance phenomenon for (Sr, M)(Ti, Li)(O, F)3 phases in the range 2 x 108-5 x 108 Hz and a dielectric relaxation in the range 9 x 106-3 x 107 Hz for BaTiO3 related materials.

لغة: إنجليزية