Temperature sensing behavior of Tm~(3+):~1G_4(a),~1G_4(b) in oxyfluoride glass ceramics containing BaYb_xY_(1-x)F_5 nanocrystals

Tm~(3+)-doped transparent oxyfluoride glass ceramics containing BaYb_xY((1-x))F_5 nanocrystals were prepared via high temperature solid phase melting method,of which up-conversion emission is achieved by the Yb~(3+)-mediated energy transfer process.The required photon number of Tm~(3+)ions emissions in BaYb_xY_((1-x))F_5 nanocrystals was calculated through the luminescence spectra,revealing the strong dependence of energy transfer mechanism on Yb~(3+)ions concentration.Meanwhile,based on the fluore scence intensity ratio technology,the effect of different energy transfer mechanism on the temperature sensitivity was investigated by the temperature-dependent luminescence intensity of thermally coupled energy levels of Tm~(3+):~1G_4(a),~1G_4(b).The obtained sensitivity decreases with the increase of Yb~(3+)ions content,which is mainly attributed to the changes in photon absorption process of Tm~(3+):~1G_4(b).