Crystal structure and temperature sensing performance of the novel Sr2Y8(1--)(SiO4)6O2:xCe3+,yTb3+ thermometric phosphors

For the research of the thermometric performance, a series of Sr ₂Y _8(1-x-y) (SiO ₄) ₆O ₂: xCe ³⁺, yTb ³⁺ phosphors were synthesized with the solid-state reaction method at N ₂/H ₂ atmosphere. The crystal structure, room and high temperature photoluminescence spectra, luminescence decay, CIE variation, energy transfer and thermometric performance have been investigated. With the ultraviolet light excitation, both the Ce ³⁺ broadband spectrum and Tb ³⁺ line spectra have been observed. With the increase of the Tb ³⁺ concentration, the emission color chromaticity varies from dark blue to bright green for the series of Sr ₂Y _{8(1–0.07-y)}(SiO ₄) ₆O ₂:0.07Ce ³⁺, yTb ³⁺ phosphors. Under high temperature, the Ce ³⁺ emission intensity quenches faster than that of Tb ³⁺. Based on the different temperature quenching speeds of Ce ³⁺ and Tb ³⁺ , the fluorescence intensity ratio technique was used to evaluate the thermometric performance of the series of Sr ₂Y _{8(1–0.07-y)} (SiO ₄) ₆O ₂:0.07Ce ³⁺, yTb ³⁺ phosphors. During the temperature range of 298–498 K, the maximum relative sensitivity values of the phosphors of y _Tb = 0.05, 0.08, 0.1, 0.15, 0.2, 0.25 were calculated as 0.65, 0.69, 0.74, 0.71, 0.66, 0.6% K ⁻¹, which are much better than the recommended value of 0.30% K ⁻¹ for the practical application. The physical mechanisms for the Ce ³⁺/Tb ³⁺ excitation and emission, energy transfer and temperature quenching have been discussed. Sr ₂Y _8(1-x-y) (SiO ₄) ₆O ₂: xCe ³⁺, yTb ³⁺ phosphors are the candidate thermometric probes for the non-contact temperature sensing applications.