Morphology of alumina in NaF-AlF3 systems determined by Raman spectroscopy and quantum mechanical calculations
Morphology of alumina in NaF-AlF3 systems determined by Raman spectroscopy and quantum mechanical calculations
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DOI：
10.1016/j.molliq.2020.113747
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发表时间：
2020-10
影响因子：
6
通讯作者：
Ming Lin;Xianwei Hu;Jiang-yu Yu;Youjian Yang;Zhongning Shi;Zhaowen Wang
中科院分区：
文献类型：
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作者：
Ming Lin;Xianwei Hu;Jiang-yu Yu;Youjian Yang;Zhongning Shi;Zhaowen Wang
采用原位拉曼光谱和量子力学计算研究了熔融NaF-AlF 3体系中含氧络合物的存在形式。NaF与AlF 3的摩尔比在1023 K、1223 K和1283 K时分别为1.22、1.9和2.7。在熔融NaF-AlF 3体系中加入氧化铝后，形成了含氧络合物Al 2 OF 4、Al 3 O2 F83-、Al 2 OF 84-和Al 2 O2 F42-。Al_2OF_4和Na_4Al_2OF_8的结构分别属于D_2d和C_2v点群，而Na_3Al_3O_2F_8和Na_2Al_2O_2F_4的结构属于C_1点群。在Al 2 OF 4、Al 3 O2 F83-、Al 2 OF 84-和Al 2 O2 F42-的实验拉曼光谱中，主带分别位于460 cm−1、530 cm−1、505 cm−1和400 cm−1。体系中含氧络离子的种类和含量与NaF/AlF 3摩尔比和Al 2 O3浓度有关。在NaF-AlF_3-Al_2 O_3熔融体系中，当NaF与AlF_3的摩尔比为1.22时，只有Al_2 OF_4生成。当摩尔比增加到1.9时，生成的含氧实体为Al 2 OF 4和Al 3 O2 F83-。当氧化铝含量低于6wt%时，两种含氧实体的含量低。当氧化铝的浓度为6wt%或更高时，Al 3 O2 F83-逐渐成为主要的含氧实体。对于NaF与AlF 3摩尔比为2.7的体系，当氧化铝浓度小于6wt%时，主要含氧实体为Al 2 OF 4、Al 3 O2 F83-和Al 2 OF 84-，但浓度较低。当氧化铝含量接近6wt%时，Al 3 O2 F83-和Al 2 OF 84-离子的浓度显著增加。当氧化铝浓度达到10重量%时，形成Al 2 O2 F42-。本文还确定了在熔融NaF-AlF_3体系中加入氧化铝后的反应方程。
In-situ Raman spectroscopy and quantum mechanical calculations were used to study the forms of oxygen-containing complexes in molten NaF-AlF3systems. The molar ratios of NaF to AlF3were varied at 1.22, 1.9, and 2.7 at temperatures of 1023 K, 1223 K, and 1283 K, respectively. Upon adding alumina to molten NaF-AlF3systems, oxygen-containing complexes, Al2OF4, Al3O2F83−, Al2OF84−, and Al2O2F42−, were formed. The structures of Al2OF4and Na4Al2OF8belong to the D2dand C2vpoint groups, respectively, while Na3Al3O2F8and Na2Al2O2F4structures belong to the C1point group. The main bands in the experimental Raman spectra of Al2OF4, Al3O2F83−, Al2OF84−, and Al2O2F42−were located at 460 cm−1, 530 cm−1, 505 cm−1, and 400 cm−1, respectively. The types and contents of the oxygen-containing complex ions in the system were related to the NaF-to-AlF3molar ratio and the concentration of alumina. In the molten NaF-AlF3-Al2O3system, with a NaF-to-AlF3molar ratio of 1.22, only Al2OF4formed. When the molar ratio was increased to 1.9, the oxygen-containing entities generated were Al2OF4and Al3O2F83−. The content of the two oxygen-containing entities was low when the alumina content was below 6 wt%. As the concentration of alumina was 6 wt% or more, Al3O2F83−gradually became the main oxygen-containing entity. For the system with a NaF-to-AlF3molar ratio of 2.7, when the alumina concentration was less than 6 wt%, the main oxygen-containing entities were Al2OF4, Al3O2F83−, and Al2OF84−, but with low concentrations. The concentrations of Al3O2F83−and Al2OF84−ions increased considerably as the alumina content approached 6 wt%. Al2O2F42−was formed when the alumina concentration reached 10 wt%. The reaction equations occurring after adding alumina to molten NaF-AlF3systems were also determined herein.