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    A simple synthesis and room temperature magnetic properties of new binary Mn0.5Fe0.5(H2PO4)2·xH2O obtained from a rapid co-precipitation at ambient temperature
    (2009-02-01) ;
    Maensiri, Santi
    ;
    Youngme, Sujittra
    ;
    Danvirutai, Chanaiporn
    A new binary Mn<inf>0.5</inf>Fe<inf>0.5</inf>(H<inf>2</inf>PO<inf>4</inf>)<inf>2</inf>·xH<inf>2</inf>O powder was synthesized by simple and cost-effective method using phosphoric acid, manganese and iron metals as starting chemicals. The synthesized solid shows the complex thermal transformations and the final decomposition product is a new binary manganese iron cyclo-tetraphosphate, MnFeP<inf>4</inf>O<inf>12</inf>. The X-ray diffraction and FTIR results indicate that the synthesized new binary Mn<inf>0.5</inf>Fe<inf>0.5</inf>(H<inf>2</inf>PO<inf>4</inf>)<inf>2</inf>·xH<inf>2</inf>O and the decomposition MnFeP<inf>4</inf>O<inf>12</inf> powders are a pure monoclinic phase with space group P2<inf>1</inf>/n (Z = 2) and C2/c (Z = 4), respectively. The particle morphologies of Mn<inf>0.5</inf>Fe<inf>0.5</inf>(H<inf>2</inf>PO<inf>4</inf>)<inf>2</inf>·xH<inf>2</inf>O and MnFeP<inf>4</inf>O<inf>12</inf> powders appear as the rod-like tetragonal shape and show a high agglomeration of small particles, which are similar to the case of Mn(H<inf>2</inf>PO<inf>4</inf>)<inf>2</inf>·2H<inf>2</inf>O and Fe<inf>2</inf>P<inf>4</inf>O<inf>12</inf>, respectively. Room temperature magnetization results show a ferromagnetic behavior of the Mn<inf>0.5</inf>Fe<inf>0.5</inf>(H<inf>2</inf>PO<inf>4</inf>)<inf>2</inf>·xH<inf>2</inf>O and MnFeP<inf>4</inf>O<inf>12</inf> powders, having the hysteresis loops in the range of -10,000 Oe < H < +10,000 Oe with the specific magnetization values of 25.63 and 13.14 emu/g at 10 kOe, respectively. The lower magnetizations of Mn<inf>0.5</inf>Fe<inf>0.5</inf>(H<inf>2</inf>PO<inf>4</inf>)<inf>2</inf>·xH<inf>2</inf>O and MnFeP<inf>4</inf>O<inf>12</inf> than those of Fe(H<inf>2</inf>PO<inf>4</inf>)<inf>2</inf>·2H<inf>2</inf>O and Fe<inf>2</inf>P<inf>4</inf>O<inf>12</inf> powders indicate the presence of Mn ions in substitution position of Fe ions. © 2008 Elsevier Masson SAS. All rights reserved.
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    A simple route to synthesize nickel ferrite (NiFe2O4) nanoparticles using egg white
    (2007-05-01)
    Maensiri, Santi
    ;
    Masingboon, Chivalrat
    ;
    ;
    Seraphin, Supapan
    NiFe<inf>2</inf>O<inf>4</inf> nanoparticles were synthesized by a simple and cost-effective method using Ni and Fe nitrates and freshly extracted egg white (ovalbumin) in an aqueous medium. The X-ray diffraction and selected-area electron diffraction results indicated that the synthesized nanoparticles have only the inverse spinel structure without the presence of any other phase impurities. Room temperature magnetization results showed a ferromagnetic behavior of the NiFe<inf>2</inf>O<inf>4</inf> nanoparticles, with saturation-specific magnetization values in the range of 26.4-42.5 emu/g at 10 kOe. © 2006 Acta Materialia Inc.
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    Item type:Publication,
    Non-isothermal decomposition kinetics of NiFe2O4 nanoparticles synthesized using egg white solution route
    (2009-01-01) ;
    Maensiri, Santi
    The thermal decomposition kinetics of nickel ferrite (NiFe <inf>2</inf>O<inf>4</inf>) precursor prepared using egg white solution route in dynamical air atmosphere was studied by means of TG with different heating rates. The activation energy (E <inf>α</inf>) values of one reaction process were estimated using the methods of Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS), which were found to be consistent. The dependent activation energies on extent of conversions of the decomposition reaction indicate "multi-step" processes. XRD, SEM and FTIR showed that the synthesized NiFe<inf>2</inf>O<inf>4</inf> precursor after calcination at 773 K has a pure spinel phase, having particle sizes of ~54 ± 29 nm. © 2009 Akadémiai Kiadó, Budapest, Hungary.
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    Item type:Publication,
    Simple synthesis, magnetic properties, and nonisothermal decomposition kinetics of Fe(H2PO4)2 · 2H2O
    (2008-10-15) ;
    Danvirutai, Chanaiporn
    ;
    Youngme, Sujittra
    ;
    Maensiri, Santi
    Fe(H<inf>2</inf>PO<inf>4</inf>)<inf>2</inf>·2H<inf>2</inf>O was synthesized by a simple and cost-effective method using iron metal and phosphoric acid as starting chemicals. The thermal transformation products from the synthesized Fe(H<inf>2</inf>PO<inf>4</inf>)<inf>2</inf> · 2H <inf>2</inf>O according to the thermal treatment at 423 and 673 K were found to be FeH<inf>2</inf>P<inf>2</inf>O<inf>7</inf> and Fe<inf>2</inf>P <inf>4</inf>O<inf>12</inf>, respectively. The activation energies of decomposition reaction of Fe(H<inf>2</inf>PO<inf>4</inf>)<inf>2</inf>· 2H<inf>2</inf>O were calculated through the isoconversional methods of Ozawa and Kissinger-Akahira-Sunose. The synthesized Fe(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, X-ray powder diffraction, and FTIR spectroscopy. Room-temperature magnetization results showed a ferromagnetic behavior of the Fe(H<inf>2</inf>PO<inf>4</inf>)<inf>2</inf>·2H <inf>2</inf>O and its thermal transformation products. The hysteresis loops were in the range -10000 Oe < H < + 10000 Oe, and the strong specific magnetization values were in the range 32.25-96.28 emu/g at 10 kOe. © 2008 American Chemical Society.
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    Item type:Publication,
    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) ;
    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.