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.

中文翻译：

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Ern +浓度和Ln3 +对LnOCl（Ln = Y，La，Gd）荧光粉中Judd-Ofelt参数的影响

掺杂三价稀土（RE ³⁺）的发光材料的光学跃迁特性已受到广泛关注。Judd–Ofelt理论是探索镧系元素4f–4f跃迁的光学跃迁特性的有效工具。这项工作的目的是发现Er ³⁺浓度和不同的Ln ³⁺离子对LnOCl：Er ³⁺（Ln = Y，La，Gd）荧光粉中Judd-Ofelt参数的影响。氧化氯LnOCl：Er ³⁺（Ln = Y，La，Gd）荧光粉是通过单置换反应技术生产的。RE ³⁺的Judd–Ofelt计算程序对掺杂的粉末进行了改性，然后用于获得所研究的磷光体中Er ³⁺的Judd–Ofelt参数。同时，提出并使用了一种检查Judd-Ofelt计算质量的新方法。已经发现，Er ^3+的掺杂浓度对YOCl和LaOCl中的Er ³⁺的光学跃迁性质有轻微的影响，但对GdOCl的光学跃迁性质有很大的影响。此外，还发现，虽然这些化合物的晶体结构相似，但Er ³⁺的光学跃迁特性也取决于Ln ³⁺（Ln = Y，La，Gd）。Er ³⁺的Judd–Ofelt参数在LaOCl：Er ³⁺中最小，在YOCl：Er中中等³⁺，但当掺杂浓度相同时，在GdOCl：Er ^3+中最大。