Pure green upconversion luminescence and temperature sensing of NaY(WO4)2:Er3+/Yb3+ prepared by molten salt method

A series of Er³⁺/Yb³⁺ co-doped NaY(WO₄)₂ (NYWO) phosphors are prepared by molten salt synthesis (MSS) with Na₂SO₄ as solvent. The holding temperature, holding time, and solvent-to-solute mass ratio parameters are regulated. The structure, morphology, and luminescence properties of the samples were tested by XRD, SEM, and fluorescence spectrometers, respectively. The lamellar sample is prepared at 900℃ for 5 h when solvent-to-solute is 3, which has the highest pure green upconversion luminescence (UCL) intensity under 980 nm laser excitation. It is demonstrated that the UCL intensity of the samples prepared by MSS is higher than that of solid sintered samples. The maximum absolute sensitivity (S_A) and relative sensitivity (S_R) are 0.012184 K⁻¹ at 507 K and 0.01102 K⁻¹ at 303 K, respectively. These materials can be used for pure green luminescence displays and temperature sensing.