Thermal Treatment Technique on Structural and Optical Properties of LaF3:Yb,Er

Due to their interesting surface and structural properties, recent years have seen the emergence of nanoparticle (NP) phosphors for use in numerous applications including defense and industry. Erbium (Er3$+)$ and Ytterbium (Yb3$+)$ doped Lanthanum fluoride (LaF3) NPs were synthesized via molten-salt synthesis (MSS) and systematically annealed to optimize crystal structure optical properties. Chemical analysis of the NPs includes X-ray diffraction (XRD) with Rietveld analysis, scanning electron microscopy (SEM), Raman, X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy, and quantum yield (QY) measurements. The study found an increase in efficiency for near-infrared (NIR) and mid-infrared (MIR) emissions, as well as for the visible spectra in the NPs. The point of oxidation producing Lanthanum oxyfluoride (LaOF), which dampens NIR and MIR emissions due to multi-phonon relaxations (MPR), is also discussed. To further elaborate the technology in photovoltaics, scintillators, and biomedical applications, optimization of emissions by LaF3:Yb,Er will help understand the highly disputed energy mechanism of Erbium; and by extension, the optical mechanisms of other rare-earth (RE) phosphors.