Investigation on luminescence properties of BaY2Si3O10:Er3+/Ho3+-Yb3+ for optical temperature sensing

To develop new upconversion (UC) phosphors for optical temperature sensing, the Er3+/Ho3+-Yb3+ doped BaY2Si3O10 (BYS) samples were synthesized by solid-state reaction method. XRD analysis reveals that single-phase samples have been successfully obtained. For the BYS:0.2Yb(3+),xEr(3+) (0.01x0.06) phosphors, three emission peaks of Er3+ appear in the visible region. The optimal Er3+ doping concentrations for 552 and 659nm emissions are different, i.e., x=0.01 and 0.02 respectively, which can be interpreted by the cross-relaxations between Er3+ ions. For Ho3+-Yb3+ codoped BYS, two strong and one weak emissions of Ho3+ are observed. The emission intensity of Ho3+ increases first and then decreases with increasing Ho3+ concentration. By investigating the temperature-dependent luminescence, it has been found that the different emission peaks in intensity show different changes with temperature, which implies both the thermally-coupled and non-thermally-coupled levels could be used for temperature sensor. The absolute and relative sensitivities by using various emissions of Er3+/Ho3+ in the BYS host were evaluated, which have been improved compared with those of some other Er3+/Ho3+ activated phosphors reported previously.