Interrelated lithium-ion transport, NTCR behavior, and dielectric-optical coupling in multifunctional Li3Mg2NbO6 ceramic.

The rapid progress of 5G/6G communication and advanced radar systems demands dielectric ceramics with excellent microwave performance and multifunctional characteristics. Lithium-based Li3Mg2NbO6 (LMN), crystallizing in a rock-salt-derived orthorhombic structure, is identified as a promising candidate due to its structural stability and tunable dielectric response. LMN ceramics were synthesized by the solid-state route and comprehensively analyzed using X-ray diffraction, UV-Vis spectroscopy, and impedance spectroscopy. The material exhibits a direct bandgap of 3.78 eV, indicating potential for optoelectronic and photocatalytic applications, while an Urbach energy of 0.92 eV reveals structural disorder affecting charge transport. Impedance results confirm thermally activated hopping conduction with an activation energy of 1.16 eV, governed by non-Debye relaxation associated with defect-mediated mechanisms. The strong correlation between structure, optical properties, and charge dynamics highlights LMN as a versatile, high-performance ceramic for next-generation microwave and UV-responsive electronic devices.