Structural study of molten lanthanum halides by X-ray diffraction and computer simulation techniques

Okamoto, Yoshihiro  ; Madden, P. A.*

The local structure of molten LaCl has been characterized by the octahedral coordination (LaCl). It is based on X-ray diffraction (XRD) and Raman spectroscopy results. On the other hand, a different structural image was proposed in the neutron diffraction (ND) and the molecular dynamics (MD) studies. These ND and MD works concluded that a coordination behavior changes with cation size in molten rare earth trichlorides. Thus, they reported the coordination number of Cl ions around La ion is 8.2 in the ND work and 7.9 in the MD work. In the present work, XRD measurements of molten LaCl were performed to investigate the local structure. The coordination number of the 1st La-Cl pair in molten LaCl was 7.1 from analysis of the correlation function G(r). The structural change by increasing anion size was examined by the XRD measurement of molten LaBr. The XRD data were nicely reproduced by the MD simulations with polarizable ionic model.