KBaYSi2O7:Yb3+-Er3+/Ho3+phosphors: Optical temperature sensing materials of high sensitivity

A train of Yb3+-Er3+ and Yb3+-Ho3+ doped KBaYSi2O7 (KBYS) phosphors were synthesized via the solid-state reaction. The corresponding photoluminescence properties were investigated systematically. Under the excitation of 980 nm, the KBYS:Yb3+,Er3+ exhibits characteristic emissions of Er3+ at 520, 558 and 661 nm; the Ho3+ in KBYS shows a strong red emission at 664 nm and a weak green emission near 549 nm. The optical temperature-sensing properties were checked by employing different strategies, where the thermally-coupled-levels (TCLs) and non-TCLs were involved. It has been found the KBYS:Yb3+,Er3+ phosphor using I-660/I-520 can produce higher absolute (S-A) and relative (S-R) sensitivities compared with that using I-520/I-558. In Yb3+-Ho3+ codoped KBYS, the I-663/I-547 value exhibits a linear relationship with absolute temperature. High S-A has been achieved, and the S-R is increased continuously with decreasing temperature. The above investigation results reveal that the phosphors in this work could be promising for applications in optical thermometer.