In this work, we prepared three CaWO₄ single crystals (CaW-0, CaW-1 and CaW-3) doped with rare earth elements (REEs) at nominal mass fractions of 50, 250 and 5000 μg g^-1 using the Czochralski method. Electron probe microanalysis (EPMA) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) were employed to evaluate the within- and between-unit homogeneity of major elements and REEs, respectively. The within-unit variation (s_r) of 0.40–0.84% and between-unit s_r of 0.14–1.48% for major elements were obtained. Within- and between-unit s_r of 0.53–5.56% were also found for REEs by LA-ICP-MS spot analyses. A comparison of the s_r of repeat analyses was compared with the analytical uncertainty (u), i.e., the mean square weighted deviation (MSWD), which is close to or slightly higher than 1, indicating that no obvious chemical heterogeneity was found in these crystals. Reference values for these elements were obtained through various analytical methods across four different laboratories and applications of the reference materials to calibrating REE mass fractions in a natural scheelite were performed. No significant difference of the results was found as t values are less than 2.75 at the 99% confidence interval. The excellent linearity (R² > 0.98) between the REE mass fractions and both LA-ICP-MS signal intensity and wafer absorbance was found, but the crater height and the absolute mass transported into ICP-MS decreased when REE mass fractions as well as the colour of crystals increased. These results suggest that the reference materials have the potential to calibrate REE mass fractions in natural scheelite.

中文翻译：

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激光烧蚀-电感耦合等离子体质谱法微量分析白钨矿中稀土元素的新型标准材料（CaW-0、CaW-1 和 CaW-3）的初步表征

在这项工作中，我们使用直拉法制备了三种标称质量分数为50、250和5000 μg g -1 的稀土元素（REE）掺杂的^CaWO ₄单晶（CaW-0、CaW-1和CaW-3） 。采用电子探针微量分析 (EPMA) 和激光烧蚀电感耦合等离子体质谱 (LA-ICP-MS) 分别评估主量元素和 REE 的单元内和单元间均匀性。主要元素的单位内变异 ( s _r ) 为 0.40–0.84%，单位间变异 ( s _{r )为 0.14–1.48%。}通过 LA-ICP-MS 点分析还发现 REE 的单元内和单元间s _{r为 0.53-5.56%。}将重复分析的sr与分析不确定度（u ）进行比较，即均方加权偏差（MSWD），_其接近或略高于1，表明这些中没有发现明显的化学异质性。晶体。这些元素的参考值是通过四个不同实验室的各种分析方法获得的，并应用参考材料来校准天然白钨矿中的稀土元素质量分数。结果没有发现显着差异，因为99% 置信区间的t值小于 2.75。发现 REE 质量分数与 LA-ICP-MS 信号强度和晶圆吸光度之间具有出色的线性关系 ( R ² > 0.98)，但当 REE 质量分数以及晶体的颜色增加。这些结果表明参考材料具有校准天然白钨矿中稀土元素质量分数的潜力。