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

In this paper, single-phase CaGd(1-x-y)T(m)xYb(y)AlO(4) (CGA:Tmx,Yby, 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 mu m. 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) -> H-3(6), (1)G(4) -> F-3(4), F-3(2,3) -> H-3(6) and H-3(4) -> H-3(6) transitions of Tm3+ 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 LIR693/801 and FWHM801 parameters. The SA-LIR and SR-LIR in the temperature range from 300 to 823 K are in the range of 0.19-6.55 x 10(-4) K-1 and 2.93-0.38 x 10-2 K-1, respectively. The SA-FWHM and SR-FWHM in the temperature range from 173 to 823 K are in the range of 4458-2044 x 10(-4) K-1 and 0.20-0.05 x 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.