A novel low dielectric constant Sr2Ga2GeO7 microwave dielectric ceramic with tetragonal structure

In this paper, Sr2Ga2GeO7 (SGG) ceramics were prepared by the solid-state method, and their microwave dielectric properties were studied. The XRD and TEM analyses show that the ceramic samples all acknowledged a tetragonal structure with the P-412 m (113) space group. The refinement results show that the lattice parameters of the ceramics sintered at 1360 °C are a = b = 8.04553 Å, c = 5.39084 Å and V = 348.9517 Å3. The Sr2Ga2GeO7 ceramics sintered at 1360 °C have a compact microstructure, and the optimum relative density is 97.5 %. Raman spectroscopy exhibited that the quality factor shows a close connection with the FWHM of the A1 g mode at 785 cm–1. The microwave dielectric properties of Sr2Ga2GeO7 ceramics sintered at 1360 °C were found to be εr = 6.52, Q × f = 32,685 GHz (f = 12.99 GHz), and τf = –37.15 ppm/°C. •A novel tetragonal Sr2Ga2GeO7 microwave dielectric ceramic with low dielectric constant and low loss was first discovered: εr = 6.52, Q × f = 32,685 GHz (f = 12.99 GHz), and τf = –37.15 ppm/°C.•We analyzed the relationship between Raman spectroscopy and microwave dielectric properties.•TEM analysis confirmed the ordered layered structure of tetragonal Sr2Ga2GeO7 ceramics.•SEM images revealed the microstructure of the ceramic grains, with the maximum relative density reaching 97.5 %.