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Journal of thermal analysis

, Volume 2, Issue 3, pp 287–299 | Cite as

The thermal decomposition of ammonium metavanadate, I

The stoichiometry of the decomposition
  • M. E. Brown
  • B. V. Stewart
Article

Abstract

The stoichiometry of the various stages involved in the thermal decomposition of ammonium metavanadate has been shown to correspond to a stepwise decrease in the ratio of ammonia and water to V2O5, with V2O5 being the final product in vacuum, in air and in argon. In ammonia, VO2 is formed. The actual stages and intermediates are dependent upon the prevailing atmosphere. Chemical analyses, together with infrared absorption spectra and X-ray powder data, have enabled the intermediates and products to be characterized and the structural changes involved in the decomposition to be discussed.

Keywords

Ammonia Argon Thermal Decomposition V2O5 Infrared Absorption 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Résumé

On montre que les différentes étapes de la décomposition thermique du métavanadate d'ammonium correspondent à la diminution progressive de l'eau et de l'ammoniac par rapport à V2O5; cet oxyde constitue le produit final dans le vide, dans l'air et dans l'argon. Dans l'ammoniac, c'est VO2 qui se forme. Les étapes respectives et les intermédiaires dépendent de l'atmosphère qui prévaut. A l'aide de l'analyse chimique, des spectres d'absorption infrarouge et des données de rayons X sur poudre, on a pu caractériser les intermédiaires et les produits formés, ainsi que les changements structuraux provoqués par la décomposition.

Zusammenfassung

Es wurde gezeigt, daß die verschiedenen Stufen in der thermischen Zersetzung von Ammoniummetavanadat dem stufenweisen stöchiometrischen Verlust von Ammonia und Wasser entsprechen. In Vakuum, Sauerstoff und Argon ist V2O5, in Ammoniak VO2 das Endprodukt. Die Zwischenprodukte der einzelnen Stufen sind von der umgebenden Gasatmosphäre abhängig. Durch chemische, infrarot- und röntgenspektroskopische Analyse gelang es, diese zu charakterisieren und so die durch die Zersetzung hervorgerufenen strukturellen Umlagerungen zu deuten.

Резюме

Показана стехиометр ия различных стадий термораспада метава надата аммиака, соответствующих сту пенчатому уменьшени ю аммиака и воды в V2O5. В вакууме, в ат мосфере воздуха и аргона коне чным продуктом являе тся V2O5. Определенные стадии и промежуточные продукты зависят от а тмосферы. Данные хими ческого анализа, спектров инфракрасного погло шения света и рентген ограммы дали возможность характе ризовать различные продукты и превращения структу ры, связанные с распадом вышеуказанного вещества.

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Copyright information

© Wiley Heyden Ltd., Chichester and Akadémiai Kiadó, Budapest 1970

Authors and Affiliations

  • M. E. Brown
    • 1
  • B. V. Stewart
    • 1
  1. 1.Chemistry DepartmentRhodes UniversityGrahamstownSouth Africa

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