Tm3+/Yb3+ codoped CaGdAlO4 phosphors for wide-range optical temperature sensing

In this paper, single-phase CaGd 1- x-y Tm x Yb y AlO 4 (CGA:Tm x ,Yb y , 0.0005 ≤ x ≤ 0.005, 0.06 ≤ y ≤ 0.14) phosphors were synthesized by a combustion method in combination with a following heattreatment. It is found that their average grain sizes are in the range of ∼0.60–1.74 μm. For these phosphors under 980 nm excitation at room temperature, four sharp emission bands at 474, 651, 693 and 801 nm can be attributed to the 1 G 4 → 3 H 6 , 1 G 4 → 3 F 4 , 3 F 2,3 → 3 H 6 and 3 H 4 → 3 H 6 transitions of Tm 3+ involving in the three-photon and two-photon processes. When x and y are equal to 0.001 and 0.10, respectively, the strongest UC emission intensity can be acquired. By employing the optimal phosphors, the wide-range temperature sensing from 173 to 823 K was realized based on LIR 693/801 and FWHM 801 parameters. The S A − L I R and S R − L I R in the temperature range from 300 to 823 K are in the range of 0.19–6.55 × 10 −4 K −1 and 2.93–0.38 × 10 −2 K −1 , respectively. The S A − F W H M and S R − F W H M in the temperature range from 173 to 823 K are in the range of 4458-2044 × 10 −4 K −1 and 0.20–0.05 × 10 −2 K −1 , respectively. Furthermore, our result demonstrates that CGA:Tm 0.001 ,Yb 0.1 phosphors has potential applications in wide-range optical temperature sensing working under extreme conditions. • Tm 3+ and Yb 3+ codoped CaGdAlO 4 phosphors were synthesized via a combustion method. • Wide-range temperature sensing was realized based on FIR and HWHM parameters. • The relative sensitivity is ∼2.93 × 10 −2 K −1 at 300 K based on FIR parameter. • The relative sensitivity is ∼0.12 × 10 −2 K −1 at 300 K based on HWFM parameter.