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Author: search.filters.author.Danvirutai, ChanaipornSubject: search.filters.subject.Thermal analysis

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    Soft solution synthesis, non-isothermal decomposition kinetics and characterization of manganese dihydrogen phosphate dihydrate Mn(H2PO4)2·2H2O and its thermal transformation products
    (2008-06-15)
    Boonchom, Banjong
    ;
    Danvirutai, Chanaiporn
    ;
    Maensiri, Santi
    Manganese dihydrogen phosphate dihydrate (Mn(H<inf>2</inf>PO<inf>4</inf>)<inf>2</inf>·2H<inf>2</inf>O) was synthesized by a simple, rapid and cost-effective method using Mn(c) and H<inf>3</inf>PO<inf>4</inf> in water-acetone medium at ambient temperature. The thermal stability of the Mn(H<inf>2</inf>PO<inf>4</inf>)<inf>2</inf>·2H<inf>2</inf>O was studied by means of the non-isothermal kinetic (Kissinger method). The specificity of thermal decomposition was characterized by identification of the bonds to be selectively activated due to energy absorption at vibrational level, which was assigned by comparison of the calculated wavenumbers with the observed wavenumbers in FTIR spectra. These results were used to identify the molecules or ions that were eliminated in each thermal transition step. The thermal transformation products from the synthesized Mn(H<inf>2</inf>PO<inf>4</inf>)<inf>2</inf>·2H<inf>2</inf>O according to the thermal treatments at 243, 773 and 1073 K were obtained to be Mn(H<inf>2</inf>PO<inf>4</inf>)<inf>2</inf>, Mn<inf>2</inf>P<inf>4</inf>O<inf>12</inf> and Mn<inf>2</inf>P<inf>2</inf>O<inf>7</inf>, respectively. The synthesized Mn(H<inf>2</inf>PO<inf>4</inf>)<inf>2</inf>·2H<inf>2</inf>O and its thermal transformation products were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and FTIR spectroscopy. The SEM micrographs of the obtained products show the different morphologies, which are important for specific applications. © 2007 Elsevier B.V. All rights reserved.
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    Nanocrystalline manganese dihydrogen phosphate dihydrate Mn(H2PO4)2·2H2O and its decomposition product (Mn2P4O12) obtained by simple precipitation route
    (2008-06-12)
    Danvirutai, Chanaiporn
    ;
    Boonchom, Banjong
    ;
    Youngme, Sujittra
    Manganese dihydrogenphosphate dihydrate (Mn(H<inf>2</inf>PO<inf>4</inf>)<inf>2</inf>·2H<inf>2</inf>O) was prepared by using MnCO<inf>3</inf>-H<inf>3</inf>PO<inf>4</inf> and Mn(c)-H<inf>3</inf>PO<inf>4</inf> systems at ambient temperature. The precipitates were investigated by thermoanalytical techniques (TG/DTG/DTA), scanning electron microscope (SEM), X-ray powder diffraction (XRD), and FTIR spectroscopy. Thermal treatment of obtained Mn(H<inf>2</inf>PO<inf>4</inf>)<inf>2</inf>·2H<inf>2</inf>O from two synthetic systems at 400 °C yielded a crystalline dehydrated manganese cyclo-tetrametaphosphate (Mn<inf>2</inf>P<inf>4</inf>O<inf>12</inf>). The XRD and FTIR results indicate that the prepared Mn(H<inf>2</inf>PO<inf>4</inf>)<inf>2</inf>·2H<inf>2</inf>O and its dehydration product Mn<inf>2</inf>P<inf>4</inf>O<inf>12</inf> from both synthetic systems have a pure monoclinic phase without the presence of any phase impurities. The lattice parameters and particles sizes analyzed from XRD spectra of Mn(H<inf>2</inf>PO<inf>4</inf>)<inf>2</inf>·2H<inf>2</inf>O and its dehydration product Mn<inf>2</inf>P<inf>4</inf>O<inf>12</inf> are different for both systems. The difference of some physical and chemical properties of Mn(H<inf>2</inf>PO<inf>4</inf>)<inf>2</inf>·2H<inf>2</inf>O and its dehydration product Mn<inf>2</inf>P<inf>4</inf>O<inf>12</inf> from both synthetic systems are discussed. Crown Copyright © 2007.