Enhancement of photoacoustic and upconversion emission in Mg2+/Zn2+ codoped Gd2O3: Er3+/Yb3+ phosphor using 980 nm excitation

Abstract

In this work, Er³⁺/Yb³⁺ doped Gd₂O₃ phosphor samples were synthesized through a combustion method and then characterized through X-ray diffraction and FE-SEM techniques. The sample was studied for photoacoustic spectroscopy (PAS) and upconversion (UC) emission spectroscopy techniques using a frequency modulated 980 nm excitation source. A correlation between PA signal (produced due to non-radiative transitions) and UC emission intensity (produced due to radiative transition) is made in order to optimize the sample for both these properties. The phosphor was codoped with Mg²⁺ and Zn²⁺ ions to see enhancement in upconversion emission intensity and these ions have enhanced the upconversion emission. Studies show that the present phosphor is appropriate for producing strong upconversion emission intensity along with a strong photoacoustic signal which is beneficial for upconversion-imaging as well as photothermal therapy. The present sample has also shown its potential for detection of fingerprints.