Ferroelectric Ceramics Related to BaTiO3 for Z5U Multilayer Capacitors

Abstract

Several pellets of general formula Ba1-xMx(Ti1-xLix)O3-3xF3x were prepared from BaTiO3, MF2 ( M = Ca, Sr, Ba or Pb ) and LiF powders then sintered by the conventional solid state route at 900 or 1000°C for 1, 2 or 4 hours. X-Ray powder diffraction patterns were collected at room temperature and SEM observations were carried out. Dielectric measurements were performed between 150 and 450K in the frequency range 50Hz - 40MHz. All the ceramics exhibit a very broad ferroelectric displacive phase transition in the temperature range 255K ≤ TC ≤ 328K.The ε' r - T curves and the values of tanδ are compatible with the Z5U class of capacitors. Furthermore, a Debye dielectric relaxation occurs in these oxifluorids in the frequency range 4MHz ≤fr ≤ 38.5MHz.