A novel low loss rare-earth germanate La4GeO8 microwave dielectric ceramic with orthorhombic structure

Abstract

This study delves into the synthesis and characterization of rare earth germanate La4GeO8 ceramics, employing the solid-phase reaction method, with a focus on their microwave dielectric properties and crystallographic characteristics. The research employs X-ray diffraction (XRD) and transmission electron microscopy (TEM) to ascertain the orthorhombic crystal structure within the Pnma space group. Rietveld refinement analysis precisely determines the lattice constants (a = 18.3006 Å, b = 7.6697 Å, c = 5.8513 Å) and unit cell volume (V = 821.28429 Å3). Raman spectroscopy provides insights into the correlation between the quality factor (Q × f) and the Full Width at Half Maximum (FWHM) of the Ag(O) mode at 733 cm⁻1. A notable highlight of the study is the exceptional microwave dielectric performance of La4GeO8 ceramic sintered at 1540 °C, characterized by a relative dielectric constant (εr) of 13.24, a Q × f product of 47,826 GHz at 10.16 GHz, and a temperature coefficient of frequency (τf) of −82.3 ppm/°C. This comprehensive investigation offers valuable insights into the structural and microwave dielectric properties of AB-type rare earth germanate La4GeO8 ceramics, underscoring their potential in advanced dielectric material applications.