The structure of concentrated aqueous solutions of chromium nitrate and cerium chloride studied by X-ray diffraction and Raman spectroscopy

• Autor(a) principal: Cabaço, M. Isabel
• Data de Publicação: 2007
• Outros Autores: Marques, M. I. de Barros, Gaspar, A. M., Marques, M. Alves, Costa, M. Margarida
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10316/4341; https://doi.org/10.1016/j.molliq.2007.08.006
• topic: Intermediate range order; Chromium nitrate cerium chloride; Concentrated aqueous solutions

Concentrated aqueous solutions of chromium nitrate and cerium chloride were investigated by X-ray diffraction and Raman spectroscopy. The X-ray diffraction patterns of two sets of solutions (1.60 up to 2.48 mol dm- 3 for chromium nitrate and 0.98 up to 2.81 mol dm- 3 for cerium chloride) display an intense maximum, prepeak, in the angular region about Q0 ~ 0.9 Å- 1 (Q = 4 [pi] sin [theta] / [lambda], [theta] being the diffracting angle). The value of Q0 corresponding to these maxima is proportional to the power 1/3 of the molar concentration. The proportionality coefficient has the value that should be observed for a close packing (fcc network) if assumed for cations. This study demonstrates, once more, the existence of an intermediate range order (up to ~ 10 Å) in very concentrated aqueous solutions of salts constituted by small ions of different valences, range order previously reported by these authors in many articles. Raman experiments are in consonance with X-ray diffraction results.