Dual-Phase Glass Ceramic: Structure, Dual-Modal Luminescence, and Temperature Sensing Behaviors

Yb3+/Er3+/Cr3+ triply doped transparent bulk glass ceramic containing orthorhombic YF3 and cubic Ga2O3 nanocrystals was fabricated by a melt-quenching route to explore its possible application in optical thermometry with high spatial and temperature resolution. It was experimentally observed that Yb3+/Er3+ ions incorporated into the precipitated YF3 nanophase, while Cr3+ ions partitioned into the crystallized Ga2O3 nanophase after glass crystallization. Importantly, such spatial isolation strategy efficiently suppressed adverse energy transfer among different active ions. As a consequence, intense green anti-Stokes luminescence originated from Er3+: 2H11/2,4S3/2 → 4I15/2 transitions, and deep-red Stokes luminescence transitions assigned to Cr3+: 2E → 4A2 radiation were simultaneously realized. Impressively, the intermediate crystal-field environment for Cr3+ in Ga2O3 made it possible for lifetime-based temperature sensing owing to the competition of radiation transitions from the thermally coupled Cr3+ 2E and 4T2 excited states. In the meantime, the low-phonon-energy environment for Er3+ in YF3 was beneficial for upconversion fluorescence intensity ratio-based temperature sensing via thermal population between the 2H11/2 state and 4S3/2 state. The Boltzmann distribution theory and the two-level kinetic model were adopted to interpret these temperature-dependent luminescence of Er3+ and Cr3+, respectively, which gave the highest temperature sensitivities of 0.25% K–1 at 514 K for Er3+ and 0.59% K–1 at 386 K for Cr3+.