A potential temperature-sensitive fluorescent material based on thermal coupling effect for temperature sensors

Fluorescent temperature sensor is a new temperature measurement technology with high-precision, fast response and no space limitation. In this work, we report a steady temperature-sensitive luminescent material Ca8Al2(1-x)(PO4)6SiO4: xDy3+ (0 ≤ x ≤ 0.13). By the X-ray power diffraction, temperature-dependent photoluminescence spectra, decay time, thermoluminescence and cathode-luminescence, we investigate the structure, luminescent characteristics and thermodynamic stability. With the increase of excitation energy, the intensity ratio of blue, yellow and red light presents an obvious distinguish. By the repetitive measurements from 25°C to 250°C-25°C-250 °C, temperature-dependent emission spectra shows an abnormal change trend. Based on a succinct energy level diagram, these phenomena can be explained reasonably. It is noteworthy that the integral area ratio of the spectrum derived from 4I15/2 and 4F9/2 transition presents excellent temperature sensing property in the temperature range from 25 to 250 °C and good stability in the repeating measurements. According to the Boltzmann distribution, the ΔE of 4I15/2 and 4F9/2 is fitted as 1052 cm−1, which is very close to the theory value. The maximum absolute and relative temperature sensitivities are 1.29 × 10−4 K−1 and 3.85% K−1, respectively. These results indicate that Ca8Al2(1-x)(PO4)6SiO4: xDy3+ may be one of the most promising temperature-sensitive material for fluorescent temperature sensors.