Optical-vibration properties of Li2ZnGeO4 dielectric ceramics

This work reports on the optical-vibration properties of Li2ZnGeO4 ceramics prepared by solid-state reactions. Single-phase, high-purity materials belonging to the monoclinic P21/n space group were obtained. Micro-Raman scattering and micro-infrared spectroscopy, besides group-theory calculations, were employed to determine and assign the phonon modes. Polarized Raman scattering was able to discern and assign a total of 36 modes, in good agreement with theoretical predictions (48 phonons were foreseen). Micro-infrared spectroscopy in the fre-quency range 50-4000 cm(-1) was applied on sintered, polished samples and a total of 30 polar modes were identified (among the 45 infrared modes predicted by group-theory calculations). Detailed dispersion analyses were conducted by using Kramers-Kronig relations as well as the Lorentz model. Intrinsic dielectric constant and quality factor were calculated as 6.2 and 387 THz, respectively. The promising results obtained in the present work showed that monoclinic Li2ZnGeO4 ceramics are suitable for applications in wireless communication devices.