A TiSnNbTaGa2O12 high-entropy microwave dielectric ceramic with rutile structure and near-zero τf

Abstract

TiSnNbTaGa2O12 (TSNTGO) high–entropy dielectric ceramic was successful synthesized using the solid-state reaction method. X–ray diffraction (XRD), Rietveld refinement and transmission electron microscopy (TEM) were used to verify that all samples have rutile structure of P42–mnm space group. The analysis of Raman spectra proved that the εr exhibited a contrary changing trend as that of Raman shift near 822 cm−1, and the same similar relationship occurred between Q×f values and full width at half maximum (FWHM). The exploration of complex chemical bonding theory (P–V–L theory) for TSNTGO ceramics suggested that the bond ionicity played a dominant role in εr, while Q×f and τf were primarily determined by lattice energy and bond energy, respectively. Notably, the TSNTGO ceramics sintered at 1275 ℃ demonstrated optimal microwave dielectric properties of εr = 33.62 ± 0.03, Q×f = 51,832 ± 1000 GHz (f0 = 6.4 GHz), and τf = –0.38 ± 0.16 ppm/℃.