Polarized Raman scattering and infrared dispersion analysis of Na₂ZnGeO₄ ceramics

Abstract

The structural, chemical, morphological, and optical‐vibration properties of Na2ZnGeO4 ceramic samples prepared by conventional solid‐state processing and sintered at 1,100°C are investigated in detail. X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and electron energy‐loss spectroscopy (EELS) showed that single‐phase samples belonging to the monoclinic Pn (= ) space group were obtained. Optical‐vibration investigations by polarized Raman and infrared spectroscopies altogether allowed us to present the characteristic features of the relevant polar phonons of the material, for the first time. Twenty‐nine out of the 45 optical modes predicted for Na2ZnGeO4 by group theory were determined, and their symmetries are revealed. The dielectric strengths of the modes that contribute to the dielectric response were obtained. Besides, the infrared dispersion parameters allowed us to calculate the extrapolated dielectric constants ε0 = 7.62 and ε∞ = 2.80, and an intrinsic quality factor Qu × f = 154 THz, at 10 GHz. The obtained values show that this material can be classified as a low‐k high‐Q ceramics, which potential applications in microwave circuitry.