Crystal structure and microwave dielectric properties of LaLuO3 ceramics

Abstract

Dense LaLuO3 ceramics were prepared by the conventional solid-state reaction route. Their room-temperature (RT) crystal structure and microwave (MW) dielectric properties were investigated. Rietveld refinements performed on X-ray diffraction data show the RT crystal symmetry to be best described by the centrosymmetric orthorhombic Pnma space group [a=6.01888 (9) A, b=8.37489 (12) A, and c=5.81841 (8) A, Z=4]. This space group assignment was further corroborated by Raman spectroscopy analysis. At RT and MW frequencies, LaLuO3 ceramics sintered at 1525 degrees C/4 h exhibit a relative permittivity, epsilon(r)=22.4, a quality factor, Q(u) x f=14 400 GHz (at 5.14 GHz), and temperature coefficient of resonant frequency, tau(f)=-7.5 ppm/degrees C. epsilon(r) corrected for porosity was calculated as 23.9.