Tunable luminescence in transparent oxyfluoride glass–ceramics containing KY₃F₁₀: Mn²⁺/Eu³⁺ nanocrystals for highly sensitive temperature sensing

Transparent glass–ceramics (GCs) encompassing Mn²⁺/Eu³⁺-doped KY₃F₁₀ (Mn²⁺/Eu³⁺: KY₃F₁₀) nanocrystals were fabricated successfully using the traditional method of melt-quenching. The Mn²⁺ and Eu³⁺ ions were confirmed incorporated in the lattices of Y³⁺ in KY₃F₁₀ nanocrystals determining from the results of change of emission intensity of Eu³⁺ and Mn²⁺, EDS, and TEM before and after micro-crystallization of glass. When Mn²⁺ was fixed at 0.5 mol% in concentration and Eu³⁺ was changed from 0 to 0.9 mol%, the emission color of the GCs was varied from green to yellow–orange and the average lifetime of Mn²⁺ ion was reduced from 8.61 to 7.38 ms. As Eu³⁺ concentration increases, the efficiency of energy transfer from the excited states of Mn²⁺ ions to Eu³⁺ ions rises, resulting in enhanced Eu³⁺ emission and diminished Mn²⁺ emission, thereby causing a change in emission color and a reduction in the lifetime of Mn²⁺ ions. An absolute sensitivity (S_a) reaching up to 0.25% K⁻¹ at 298 K and a relative sensitivity (S_r) of 0.62% K⁻¹ at 298 K were derived by analyzing the fluorescence intensity ratio (FIR) between 540 nm of Mn²⁺ and 613 nm of Eu³⁺ ions. The transparent GCs with physico-chemical stability and good luminous efficiency have application prospects for multicolor display applications and temperature sensors.