Enhancing temperature sensing behavior of NaLuF4:Yb3+/Er3 via incorporation of Mn2+ ions resulting in a closed energy transfer

Abstract A strategy to improve the sensitivity of NaLuF 4 :Yb 3+ /Er 3+ is elaborated via incorporation Mn 2+ ions, which results a closed energy transfer between Er 3+ and Mn 2+ ions ( 4 S 3/2 (Er 3+ ) →  4 T 1 (Mn 2+ ) →  4 F 9/2 (Er 3+ )). The NaLuF 4 :Yb 3+ /Er 3+ and NaLuF 4 :Yb 3+ /Er 3+ /Mn 2+ phosphors are prepared by a hydrothermal method. Notably, incorporation Mn 2+ for NaLuF 4 :Yb 3+ /Er 3+ phosphor rusults in enhancing the red to green intensity ratio, which acts as a bridge for energy transfer between 4 S 3/2 and 4 F 9/2 levels of Er 3+ . The temperature sensing behaviors of two phosphors are investigated in the 295–595 K range using a ratiometric technique under 980 nm excitation. Based on thermally ( 2 H 11/2 and 4 S 3/2 ) and non-thermally ( 4 F 9/2 and 4 S 3/2 ) coupled levels of Er 3+ , the influences of this energy transfer are discussed in detail. The sensitivity of NaLuF 4 :Yb 3+ /Er 3+ doping with Mn 2+ ions based on non-thermally coupled levels is much higher than that without Mn 2+ ions based on both thermally and non-thermally coupled levels in the 295–525 K range. The maximum sensitivity is 10.99 × 10 −3  K −1  at 295 K for NaLuF 4 :Yb 3+ /Er 3+ /Mn 3+ phosphor. These meaning results indicate that incorporation Mn 2+ ions in NaLuF 4 :Yb 3+ /Er 3+ phosphor is an effective method for enhancing sensitivity in the 295–525 K range.