Enhancement of the Dielectric Constants of (Ta2O5)1−x(TiO2)x by Dielectric Anisotropy in Polycrystalline Ceramics

Abstract

(Ta2O5)1−x(TiO2)x system ceramics has been studied intensively as a promising dielectric material for next generation of high density dynamic random access memories instead of SiO2 and Si3N4. The (Ta2O5)1−x(TiO2)x ceramics with highly dielectric anisotropy can be obtained by applying relatively higher cold uniaxial pressure (200 MPa) and a high sintering temperature (1550°C) to the cylindrical pellet. The dielectric permittivity of (Ta2O5)1−x(TiO2)x ceramics can be dramatically enhanced 1.5–1.8 times than the conventional disk specimen by cutting the cylindrical pellet parallel to the pressing axis. The mechanism of enhancement of dielectric constants is involved in the appearance of Hmon-TiTa18O47 solid-solution phase, preferentially grain growth and densification in (Ta2O5)1−x(TiO2)x ceramics. It is also suggested that the present work can be developed a sort of technology to enhance the physical properties of Ta2O5-based functional ceramics, esp. in dielectric properties.