Temperature programmed decomposition of thorium nitrate pentahydrate
2000; Elsevier BV; Volume: 278; Issue: 2-3 Linguagem: Inglês
10.1016/s0022-3115(99)00261-5
ISSN1873-4820
AutoresS. Dash, M. Kamruddin, P.K. Ajikumar, A.K. Tyagi, Baldev Raj, Santanu Bera, S.V. Narasimhan,
Tópico(s)Thermal and Kinetic Analysis
ResumoTemperature programmed decomposition (TPD) of thorium nitrate pentahydrate has been studied using evolved gas analysis–mass spectrometry (EGA-MS) in the temperature range 300–1200 K. A thermogravimetric (TGA) investigation was also carried out in the same temperature range. Complexity of the TGA decomposition profile was resolved through use of EGA-MS data. The activation energies and pre-exponential factors were determined for various gas release stages from the fractional extent of decomposition plots. Residues left over after each decomposition stage were analysed using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The XRD investigations revealed formation of a nanocrystalline thoria intermediate product, ultimately agglomerating to a microcrystalline phase. The XPS investigations indicated systematic alteration in the chemical environment around the thorium atom while the Th4+ oxidation state remained unchanged. This was further corroborated from the analysis of shake-up satellites of Th (4f5/2) spectra. The O/Th ratios for various intermediate products were also determined.
Referência(s)