Microwave dielectric and thermal properties of mixed rare earth ortho phosphate [REmixPO4]

Abstract

A cost effective protocol to develop microwave substrate is proposed whereby a mixed rare earth orthophosphate [REMIXPO4] ceramic was prepared using a natural mixture of rare earth oxides, which is a byproduct derived from beach sand after thorium extraction. The Rietveld refinement of X-ray powder diffraction pattern confirms that the compound belongs to P2(1)/n space group with monoclinic crystal symmetry. The scanning electron microscopy combined with energy dispersive X-ray analysis was performed to study the surface morphological characteristics. The ceramic sintered at 1250 degrees C showed a relative permittivity (epsilon(r)) of 9.6 (at 13.5 GHz), high quality factor (Q(u) x f) of 45,200 GHz and a tau(f) of -35 ppm/degrees C. The room temperature thermal conductivity of the sintered ceramic is 3.25 Wm(-1) K-1 while the average coefficient of thermal expansion (CTE) is 7.3 ppm/degrees C.