Andersen K B, Christensen E, Berg R W, Bjerrum N J, von Barner J H
Department of Chemistry, Building 207, Technical University of Denmark, DK 2800 Lyngby, Denmark.
Inorg Chem. 2000;39(16):3449-54. doi: 10.1021/ic991057t.
A vacuum-tight cell for infrared spectroscopic investigations of extremely corrosive melts, e.g., molten fluorides, has been constructed and tested up to 750 degrees C. The cell has a gold-lined sample chamber and a diamond window transparent for the infrared light. It can be furnished with a gold piston that enables the recording of short-path-length FTIR spectra of liquid samples. Solutions of Nb(V) in LiF-NaF-KF eutectic (FLINAK) with and without oxide additions have been investigated by FTIR and Raman spectroscopy. The presence of NbF7(2-), NbOF5(2-), and NbO2F4(3-) complexes was established in the molten state at 600 degrees C. After solidification NbF7(2-) was still the only Nb(V) all-fluoro complex present. Three oxofluoro complexes, NbOF6(3-), NbOF5(2-), and NbO2F4(3-), have been identified in the solid state. Typical frequency regions for the different complexes are established. Finally, it was shown that K2NbF7 can be used as an indicator to determine the oxide content of the sample melts.
已构建了一种用于对极具腐蚀性的熔体（如熔融氟化物）进行红外光谱研究的真空密封池，并在高达750摄氏度的温度下进行了测试。该池具有内衬金的样品腔和对红外光透明的金刚石窗口。它可以配备一个金活塞，用于记录液体样品的短程傅里叶变换红外光谱（FTIR）。通过FTIR和拉曼光谱对添加和不添加氧化物的铌（V）在LiF-NaF-KF共晶（FLINAK）中的溶液进行了研究。在600摄氏度的熔融状态下确定了NbF7(2-)、NbOF5(2-)和NbO2F4(3-)配合物的存在。固化后，NbF7(2-)仍然是唯一存在的铌（V）全氟配合物。在固态中鉴定出了三种氧氟配合物，即NbOF6(3-)、NbOF5(2-)和NbO2F4(3-)。确定了不同配合物的典型频率区域。最后，结果表明K2NbF7可用作测定样品熔体中氧化物含量的指示剂。
