Concentration dependence of the structure of aqueous solutions of samarium trichloride according to X-ray diffraction

Abstract

Aqueous solutions of samarium chloride in a wide range of concentration under ambient conditions are studied by X-ray diffraction analysis. The small-angle peaks in experimental scattering intensity curves are interpreted. It is shown that highly concentrated solutions are characterized by a unique structure that differs heavily from the structure of dilute systems. It is found that small-angle peaks also appear in the intensity curves of dilute solutions, indicating that the so-called long-range order is preserved in these solutions. It is revealed that the contributions to the total scattering pattern that govern the appearance of prepeaks are interionic interactions of different types (e.g., cation-cation, anion-cation, and anion-anion interactions) in concentrated systems and the distances between the cations in dilute solutions.