The effect of K+ ion exchange on the structure and thermal reduction of hexagonal ammonium tungsten bronze

• Published in: Journal of thermal analysis and calorimetry 2009-07, Vol.97 (1), p.11-18
• Main Authors: Szilágyi, I. M., Madarász, J., Pokol, G., Hange, F., Szalontai, G., Varga-Josepovits, Katalin, Tóth, A. L.
• Format: Article
• Language: English
• Subjects: AMMONIUM COMPOUNDS; Analytical Chemistry; BRONZES; CALORIMETRY; Channels; Chemistry; Chemistry and Materials Science; COMPOSITES; Exact sciences and technology; Inorganic Chemistry; Inorganic chemistry and origins of life; ION EXCHANGE; Measurement Science and Instrumentation; MICROSTRUCTURES; Miscellaneous; Nanocomposites; Nanomaterials; Nanostructure; Physical Chemistry; Polymer Sciences; Preparations and properties; REDUCTION; Thermal reduction; Tungsten bronze; X RAY SPECTROSCOPY; X-ray photoelectron spectroscopy
• ISSN: 1388-6150; 1588-2926; 1572-8943
• DOI: 10.1007/s10973-008-9752-1

This paper discusses the changes in the structure and thermal reduction of nanosize hexagonal ammonium tungsten bronze (HATB), (NH 4 ) 0.33−x WO 3−y , which were caused by K + ion exchange (doping) and studied by XRD, XPS, 1 H-MAS NMR, FTIR, SEM and TG/DTA-MS. Comparison of the cell parameters of undoped and doped HATB revealed that both a and c cell parameters decreased after the ion exchange reaction, which showed that smaller K + ions partly replaced the larger NH 4 + ions in the hexagonal channels of HATB. After the reaction, from the hexagonal channels less NH 3 evolved, which also supported the incorporation of K + ions into the hexagonal channels.