Influence of Er3+ concentration and Ln3+ on the Judd–Ofelt parameters in LnOCl (Ln = Y, La, Gd) phosphors

The optical transition properties of trivalent rare earth (RE3+) doped luminescent materials have received extensive attention. The Judd–Ofelt theory is an effective tool for exploring the optical transition properties for the 4f–4f transitions of lanthanides. The aim of this work is to discover the effect of Er3+ concentration and different Ln3+ ions on the Judd–Ofelt parameters in LnOCl:Er3+ (Ln = Y, La, Gd) phosphors. Oxychloride LnOCl:Er3+ (Ln = Y, La, Gd) phosphors were produced via a single displacement reaction technique. The Judd–Ofelt calculation procedure for RE3+ doped powders was modified and then adopted to obtain the Judd–Ofelt parameters of Er3+ in the studied phosphors. Meanwhile, a new route for examining the Judd–Ofelt calculation quality was proposed and used. It was found that the Er3+ doping concentration slightly affects the optical transition properties of Er3+ in YOCl and LaOCl, but greatly affects the optical transition properties in GdOCl. Moreover, it was also found that the optical transition properties of Er3+ depend also on Ln3+ (Ln = Y, La, Gd) though the crystal structure of these compounds is similar. The Judd–Ofelt parameters of Er3+ are the smallest in LaOCl:Er3+, medium in YOCl:Er3+, but the biggest in GdOCl:Er3+ when the doping concentration is the same.