Solid-state synthesized Li4GeO4 germanate: an exploration of its structure, vibrational characteristics, electrical conductivity, and dielectric properties

Abstract

Orthogermanate materials have obtained considerable interest due to their unique physical and chemical properties, enabling diverse applications in the field of optoelectronics. This study explores the synthesis, vibrational properties, and electrical conduction mechanisms of the ceramic compound Li₄GeO₄. The sample was successfully synthesized using a high-temperature solid-state reaction. The Li₄GeO₄ compound crystallizes in the orthorhombic system (Bmmb space group). The morphological distribution and grain size of the titled compound were analyzed using SEM studies. The crystal structure was examined using Raman spectroscopy, confirming the presence of the functional group [GeO₄]⁴⁻. Additionally, a detailed analysis of Nyquist plots demonstrates the sensitivity of the material's electrical characteristics to variations in frequency and temperature. Applying Jonscher's power law to the ac conductivity versus temperature reveals a change in the exponent “S”, which is explained by a change in the conduction mechanism, and consistent with the OLPT model below 573 K and the CBH model above. Utilizing the Maxwell–Wagner effect as proposed by the Koop phenomenological theory, the thermal variation of permittivity has been analyzed. The compound exhibits low dielectric loss values and a high permittivity (ε ∼ 10⁶ F m⁻¹). Additionally, its electrical capacitance reaches a promising value of 123 μF at 673 K, making it a strong candidate for energy storage applications, such as lithium-ion batteries.