Tunable red-to-green emission ratio and temperature sensing properties of NaLuF4:Ho3+/Yb3+ microcrystals by doping with Ce3+ ions

Abstract

In this work, β-NaLuF₄:20Yb³⁺/2Ho³⁺ samples with different concentrations of Ce³⁺ ions are obtained by a hydrothermal method. With introducing 12 mol% Ce³⁺ ions, the red–green intensity ratio increases 9.67 times compared with that of the undoped sample, realizing emission color adjustment from green to red. Such color tunable emission may be attributed to the cross-relaxation process between Ce³⁺ and Ho³⁺ ions. In addition, doping with Ce³⁺ ions results in the increase of absolute sensitivity from 0.0036 K⁻¹ to 0.0437 K⁻¹, which is an almost 12.14 times enhancement. This may be due to the Ce³⁺ ions influencing the energy transfer process and increasing the sensitivity to environmental temperature changes. Thus, the β-NaLuF₄:20Yb³⁺/2Ho³⁺ microcrystals with Ce³⁺ ions have potential to be applied as temperature sensors.