In Situ X-ray Diffraction Studies of the Crystallization of Layered Manganese Thioantimonates(III) under Hydrothermal Conditions

• Published in: Chemistry of materials Vol. 13; no. 4; pp. 1383 - 1390
• Main Authors: Engelke, L, Schaefer, M, Schur, M, Bensch, W
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 16-04-2001
• Subjects: Chemistry; Colloidal state and disperse state; Condensed matter: structure, mechanical and thermal properties; Disperse systems; Exact sciences and technology; General and physical chemistry; Inorganic chemistry and origins of life; Inorganic compounds; Physics; Powders; Preparations and properties; Salts; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Polycrystal; Solvothermal synthesis; Experimental study; X ray diffraction; Powder; Inorganic compound; Diamine; Lamellar structure; Transition metal compounds; Energy dispersion; Manganese Thioantimonates; Growth mechanism; Reaction mechanism; Crystal growth from solutions; Crystal nucleation; Kinetics; Activation energy; Organic compounds
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/cm001234k

The solvothermal synthesis of the layered compound Mn2Sb2S5·DAP (DAP = 1,3-diaminopropane) has been studied using in situ energy-dispersive X-ray diffraction. The results clearly demonstrate that the induction time strongly depends on the reaction temperature. At lower temperatures two crystalline intermediates could be detected. The decay of the second intermediate and the product growth show a strong correlation. A detailed analysis of the extent of reaction α suggests that a small fraction of the intermediate is either dissolved or converted into an amorphous state. The experimentally determined extent of reaction α versus time was compared with various theoretical models. The reaction exponents indicate similar mechanisms for temperatures between 105 and 125 °C. The best agreement is obtained with a first-order reaction and/or phase-boundary-controlled mechanisms. A rigorous analysis reveals that it is highly likely that with increasing α the mechanism changes, suggesting consecutive and/or parallel kinetics as the reaction proceeds. At 130 °C and α > 0.75 a three-dimensional diffusion-controlled process dominates.