Reliable temperature sensing based on intense green upconversion emissions of Y2Mo4O15:Yb3+,Er3+ under 980 nm excitation

In this paper, Y 2 Mo 4 O 15 :Yb 3+ /Er 3+ upconversion phosphors are prepared by a co-precipitation method. In the case of 20% Yb 3+ doping, the intense green upconversion luminescence is obtained, which can be attributed to the energy transfer from Yb 3+ -MoO 4 2- dimer to Er 3+ that suppresses the multi-phonon relaxation of 4 I 11/2 to 4 I 13/2 . Similar the Yb 3+ sensitization, the dimer sensitization is also dependent on the Yb 3+ concentration. When the Yb 3+ concentration exceeds 20%, the luminescence is quenched by the cross relaxation and energy migration between dimers. A method for evaluating the reliability of temperature measurement standards is reported. Moreover, in term of the reliable temperature scale, the maximum absolute sensitivity of sample doped with 20% Yb 3+ is determined to be 0.0117 K -1 . Favorable sensing ability and strong upconversion luminescence indicate that the optimum sample is potentially applicable as the optical thermometric materials.