Dielectric Properties of (Al3+, Nb5+) Co-Doped CaTiSiO5 Ceramics at Elevated Temperature

The CaTi(1-x)(Al0.5Nb0.5)(x)SiO5(0 <= x <= 0.1) ceramics were prepared by the conventional solid-state method. Al and Nb co-doping improved the high temperature stability of the CaTiSiO5 material and no obvious phase transition was found at temperature up to 623 K for x >= 0.03. A dielectric constant of 53, dielectric loss of 0.001, resistivity of 8.5 x 10(13)Omega cm, and breakdown strength of 1064.7 kV/cm was obtained for the CaTi0.97(Al0.5Nb0.5)(0.53)SiO5 ceramics at room-temperature. The dielectric constant is stable over a wide temperature range and a resistivity of 9.0 x 10(10) Omega cm could still be achieved up to 573 K. The P-E loops measurements showed that energy storage efficiencies of 96% and 88.6% could be obtained at room-temperature and 453 K, respectively, for the CaTi0.57(Al0.5Nb0.5)(0.03)SiO5 ceramics. The excellent dielectric properties at elevated temperature indicate that titanite based ceramics stabilized by Al and Nb co-doping could be promising candidates for high temperature ceramic capacitors application.