Crystal structure and microwave dielectric properties of LaLuO3 ceramics

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) Å, b=8.37489 (12) Å, and c=5.81841 (8) Å, Z=4]. This space group assignment was further corroborated by Raman spectroscopy analysis. At RT and MW frequencies, LaLuO3 ceramics sintered at 1525°C/4 h exhibit a relative permittivity, ɛr=22.4, a quality factor, Qu×f=14 400 GHz (at 5.14 GHz), and temperature coefficient of resonant frequency, τf=−7.5 ppm/°C. ɛr corrected for porosity was calculated as 23.9.