Crystal structures, bond characteristics, and microwave dielectric properties of Ca2LaNbO6 ceramics

Ca2LaNbO6 (CLN) ceramics were synthesised using a solid-state reaction process. The CLN ceramics were characterised through X–ray diffraction, transmission electron microscopy, and Rietveld refinement, and it was confirmed that they crystallised into a pure Ca2LaNbO6 phase with a monoclinic structure. The analysis of Raman spectra verified that the εr exhibited a variation tendency contrary to that of Raman shift near 744 cm−1. The Q×f was highly dependent on the lattice energy (Ub), full width at half-maximum, and packing fraction, and the τf was mainly affected by bond energy (Eb). Furthermore, P–V–L analysis indicated that both the ionicity (fi) and Ub depended heavily on the Nb–O bond, whereas Eb was dominated by the Ca–O bond. The CLN ceramics sintered at 1175 ℃ exhibited favourable microwave dielectric properties, including εr of 21.92 ± 0.077, Q×f of 63,207 ± 500 GHz (f0 = 8.2 GHz), and τf of -8.06 ± 0.41 ppm/°C.