Magnetic tuning in upconversion emission enhanced through Ag+ ions co-doped in GdF3: Ho3+/Yb3+ phosphor and a real-time temperature sensing demonstration

Herein Ho³⁺/Yb³⁺ doped GdF₃ phosphor was prepared by chemical coprecipitation method. Further, during sample preparation, Ag⁺ ions were incorporated into the GdF₃ lattice to enhance the upconversion emission. Using 980 nm excitation intense emission bands were observed at 543 nm and 650 nm corresponding to the ⁵F₄→ ⁵I₈ and ⁵F₅→⁵I₈ transitions. Incorporation of Ag⁺ ions has resulted in enhancement in the emission and maximum intensity was obtained for the Ag⁺ concentration of 10 mol%. It was supposed that Ag⁺ ions change the crystal field around the Ho³⁺ ions that result in emission enhancement. The Ag⁺ incorporation was also confirmed through UV–vis absorption and downconversion analysis. The effect of the magnetic field was studied on the emission intensity and an optical hysteresis loop was observed in the plot of emission intensity vs the magnetic field. The CIE color coordinate variation based temperature sensing ability of the optimized sample is also demonstrated.