Structural and electrical characterization of CeAlO3 ceramics

Abstract

The crystal structure and electrical properties of CeAlO3 ceramics prepared by the mixed oxide route have been investigated. X-ray and electron diffraction data show the room temperature structure to be described by the tetragonal I4∕mcm space group [a=5.3253(5)Å and c=7.5860(9)Å; Z=4, and theoretical density, Dx=6.64g∕cm3]. CeAlO3 ceramics sintered at 1500°C under flowing 5%H2–95%N2 gas for 4h reach ∼94% of Dx with a microstructure of randomly distributed equiaxed grains of average grain size ∼2μm. Conventional transmission electron microscopy reveals needle-shaped ferroelastic domains in some grains. The relative permittivity εr of CeAlO3 ceramics is ∼18–20 in the range of ∼10–300K. At room temperature and microwave frequencies, CeAlO3 ceramics exhibit εr∼20.7, Qfr∼40117GHz (at 9.5GHz), and τf∼−57ppm∕K. The ion polarizability for Ce3+ is calculated to be 4.46Å3. Revised dielectric polarizabilities for rare-earth lanthanides are also presented.