Effect of Mg2+ and Zn2+ addition on photoluminescent and photoacoustic spectroscopy of La2O3:Er3+/Yb3+ phosphors

Photoluminescence (PL) and photoacoustic spectroscopy (PAS) are important techniques for materials characterization. The La2O3: Er3+/Yb3+ phosphors samples were synthesized by combustion method and annealed at 800–1200 °C for 2 h for improved photoluminescence properties. XRD data confirmed that all samples have pure hexagonal phase and FE-SEM shows irregular granular-like morphological structures and particle size that improved with annealed temperature. Then the photoacoustic (PA) amplitude and upconversion (UC) emission intensity were successively measured by a homemade PA cell under 980 nm laser excitation. A comparative relationship was made between PA and UC varying excitation power. Then, the authors showed the effect of codoped Mg2+ and Zn2+ ions on the radiative and non-radiative properties. It is observed that UC emission intensity for Zn2+ codoped La2O3: Er3+/Yb3+ phosphor has maximum, and also observed prominent absorption peaks at 521, 658, and 955 nm. These results indicate its high potential for application in photo-thermal therapy and upconversion imaging.