Enhancement of Visible Upconversion Emission in Y₂O₃:Er³⁺-Yb³⁺ by Addition of Thiourea and LiOH in the Phosphor Synthesis

Table 2

Decay times of energy levels as a function of different precipitant agents.

Emission transition	Peak wavelength	Thiourea-LiOH	Urea-LiOH	LiOH	Urea
→	563 nm	0.807 ms	0.577 ms	0.574 ms	0.515 ms
→	660 nm	1.170 ms	0.863 ms	0.856 ms	0.611 ms
→	1030 nm	1.780 ms	1.30 ms	1.280 ms	1.090 ms
→	1535 nm	13.50 ms	9.960 ms	8.820 ms	8.110 ms