Enabling Visible and Near-Infrared Dual-Mode Emissions in Polycrystalline Gd₂Hf₂O₇ Transparent Ceramics

Rare-earth-doped transparent ceramics, as novel luminescent materials, show broad application prospects in the field of advanced photonics. In this study, a series of Gd₂Hf₂O₇:Yb³⁺,Er³⁺ transparent ceramics were prepared by controlling Yb³⁺ concentration via vacuum sintering. These ceramics exhibit a dense microstructure that effectively suppresses light scattering and nonradiative relaxation, enabling simultaneous visible light, near-infrared emission, and upconversion luminescence within a single ceramic system. The dual-mode emissions are attributed to the strong near-infrared absorption of Yb³⁺ ions, as well as the efficient Yb³⁺ → Er³⁺ energy transfer under 980 nm excitation and the presence of Er³⁺ → Yb³⁺ energy transfer under ultraviolet light. Furthermore, these ceramics exhibit superior environmental resilience and hydrophobic properties. Accelerated hydrothermal aging tests reveal negligible phase decomposition, minimal decay in near-infrared and upconversion luminescence, and significantly enhanced performance compared to commercial aluminate phosphors. This property stems from the inherent chemical stability and dense structure of the ceramics. Gd₂Hf₂O₇-based dense transparent ceramics, characterized by dual-mode luminescence, high transmittance, and exceptional durability, hold promise in addressing the stability limitations and integration challenges in harsh environments and high-power optoelectronic devices.