Multifunctional ceramics Ba1−xSrx(Ti1−xLix)O3−3xF3x

Mixtures of (1 − x)BaTiO3 + xSrF2 + xLiF are prepared and dry-ground. The powders thus obtained are shaped to discs and sintered in free-air at 950 °C for 2 h. The shrinkage coefficient varies between 14.5% and 16.8%. The XRD patterns show the formation of a new solid solution with general formula Ba1−xSrx(Ti1−xLix)O3−3xF3x which occurs in the composition range 0 ≤ x ≤ 0.25. The ceramic grain size is observed by Scanning Electron Microscopy (SEM) on fractured samples. The phase transitions in these perovskite-type oxifluorides are investigated by Differential Scanning Calorimetry (DSC) and dielectric measurements. The sintering temperature (tsin t ≈ 1400 °C) and the ferroelectric Curie temperature (TC ≈ 120 °C) of BaTiO3 are strongly lowered by the triple substitution Ba–Sr, Ti–Li and O–F. The value of TC for Ba0.95Sr0.05(Ti0.95Li0.05)O2.85F0.15 is around −65 °C. These new phases are suitable for the fabrication of capacitors in various microelectronic devices.