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Characterization and thermal investigations of ammonium heptamolybdate

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Abstract

Thermal decomposition of ammonium heptamolybdate was studied by means of differential scanning calorimetry and thermogravimetry. DSC showed that the material decomposes in the temperature region 463–608 K in static air atmosphere, in three steps. The products of decomposition were characterized by IR spectroscopy, elemental analysis and magnetic susceptibility measurements. All the phases are paramagnetic in nature. Kinetic analysis suggested that the first two steps are controlled by a diffusion mechanism, while the third step is controlled by nuclear-growth.

Zusammenfassung

Mittels Differential-Scanning-Kalorimetrie und Thermogravimetrie wurde die thermische Zersetzung von Ammoniumheptamolybdat untersucht. Laut DSC zersetzt sich die Substanz in statischer Luftatmosphäre im Temperaturbereich von 463 bis 608 K in drei Schritten. Die Produkte wurden durch IR-Spektroskopie, Elementaranalyse und Messungen der magnetischen Suszeptibilität charakterisiert. Alle Phasen sind paramagnetischer Natur. Kinetische Untersuchungen besagen für die ersten zwei Schritte einen diffusionskontrollierten, für den dritten Schritt einen wachstumskontrollierten Mechanismus.

РЕжУМЕ

с пОМОЩьУ ДИФФЕРЕНцИ АльНОИ скАНИРУУЩЕИ кАлОРИМЕтРИИ И тЕРМО гРАВИМЕтРИИ ИжУЧЕНО тЕРМИЧЕскОЕ РАжлОжЕНИЕ гЕптАМОД ИБДАтА АММОНИь. РЕжУльтАты Д ск пОкАжАлИ, ЧтО ВЕЩЕстВО В стАтИЧЕск ОИ АтМОсФЕРЕ ВОжДУхА РАжлАгАЕтсь В тЕМпЕРАтУРНОМ ИНтЕ РВАлЕ 463–608 к В тРИ стАДИИ. пРОДУкты Р АжлОжЕНИь БылИ ОхАРАктЕРИжОВАНы Ик спЕктРАМИ, ЁлЕМЕНтНы М АНАлИжОМ И ИжМЕРЕНИь МИ МАгНИтНОИ ВОспРИИ МЧИВОстИ. ВсЕ ОБРАжУУЩИЕсь пРИ ЁтОМ ФАжы ьВльлИсь пАРАМАгНИт НыМИ. кИНЕтИЧЕскИИ АН АлИж пОкАжАл, ЧтО пЕРВыЕ ДВ Е стАДИИ кОНтРОлИРУУ тсь ДИФФУжИОННыМ МЕхАНИ жМОМ, тОгДА кАк тРЕтьь стАДИь —РОстОМ цЕНтРОВ кРИстАллИжАцИИ.

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Authors and Affiliations

  1. Department of Chemistry, University of Jammu, 80004, Jammu (Tawi), India

    I. B. Sharma & S. Batra

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  1. I. B. Sharma
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  2. S. Batra
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The authors are grateful to the UGC, New Delhi, for financial assistance.

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Sharma, I.B., Batra, S. Characterization and thermal investigations of ammonium heptamolybdate. Journal of Thermal Analysis 34, 1273–1281 (1988). https://doi.org/10.1007/BF01914351

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  • DOI: https://doi.org/10.1007/BF01914351

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