Abstract ErF3 doped BaF2 crystals were obtained using the vertical Bridgman technique. Five crystals, with 0.05, 0.08, 0.1, 0.2 and 0.5 mol% ErF3 added to the starting material, have been investigated. The optical absorption spectra reveal the characteristic bands of the Er3+ ions. The distribution of Er3+ ions along the crystals was studied using the optical absorption spectrum of every samples (14-18 slices) cleaved from the as-grown crystals. The Er3+ ions are not uniform distributed along the BaF2 crystals. The segregation coefficient, k, was calculated using the so-called optical absorption method and the Scheil relationship between the dopant concentration and crystal growth conditions. The calculated segregation coefficient of the Er3+ ions ranges from 0.76 to 0.98, for ions with trigonal (C3v) sites, and from 0.6 to 0.86 for clusters, depending on the ErF3 concentration. In the investigated temperature range, only one type of dielectric relaxation has been observed. This relaxation, with activation energy of 0.54 eV is associated with trigonal NNN type (C3v) centers. The charge compensating defects were discussed taking into account both the optical absorption spectra and the calculated number of NNN dipoles whose relaxation were observed.

中文翻译：

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ErF3 掺杂 BaF2 晶体的生长和表征

摘要 使用垂直布里奇曼技术获得了 ErF3 掺杂的 BaF2 晶体。已经研究了五种晶体，分别在起始材料中添加了 0.05、0.08、0.1、0.2 和 0.5 mol% ErF3。光吸收光谱揭示了 Er3+ 离子的特征带。使用从生长的晶体上切割的每个样品（14-18 个切片）的光吸收光谱研究 Er3+ 离子沿晶体的分布。Er3+ 离子沿 BaF2 晶体分布不均匀。偏析系数 k 使用所谓的光吸收法和掺杂剂浓度与晶体生长条件之间的 Scheil 关系计算。对于具有三角 (C3v) 位点的离子，计算出的 Er3+ 离子的分离系数为 0.76 至 0.98，而对于簇为 0.6 至 0.86，取决于 ErF3 的浓度。在研究的温度范围内，仅观察到一种类型的介电弛豫。这种弛豫具有 0.54 eV 的活化能，与三角 NNN 型 (C3v) 中心有关。考虑到光学吸收光谱和观察到弛豫的 NNN 偶极子的计算数量，讨论了电荷补偿缺陷。