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Author: search.filters.author.Kullyakool, Saifon

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    Characterization, Kinetic Using Deconvolution Techniques and Thermodynamic Study of Synthetic MgHPO4·3H2O
    (2023-04-01)
    Kullyakool, Saifon
    ;
    Thompho, Somphob
    ;
    Boonchom, Banjong
    ;
    Rungrojchaipon, Pesak
    MgHPO<inf>4</inf>·3H<inf>2</inf>O was synthesized via a simple wet reaction and transformed to its final decomposed product, Mg<inf>2</inf>P<inf>2</inf>O<inf>7</inf> at 873 K. The thermal properties, vibrational modes of block units, and solid phases of the synthetic compounds have been investigated by TG/DTG/DTA, FTIR, and XRD techniques. The temperature dependence of thermodynamic properties estimated from the DSC data occurred in two regions (before and after the dehydration reaction) indicating a characteristic of the prepared MgHPO<inf>4</inf>·3H<inf>2</inf>O sample. The dehydration reactions of 3.5 mol of water molecules in the structure overlapped in the temperature of 363–823 K and showed the phase transition at 921 K as revealed by TG/DTG/DTA. The deconvolution technique using the newly modified co-mathematical functions was used to separate the overlapped dehydration steps in the DTG curve, which obtained the three steps. Only the first and second steps were estimated using kinetic triplet parameters (E<inf>a</inf>, A, and model), which indicate the single dehydration mechanism with the A<inf>1.25</inf> model and the multi-step of a parallel mechanism with the A<inf>1.6</inf> model, respectively. The data of kinetics and thermodynamics play key points in theoretical study, application development, and industrial production of magnesium phosphates as a theoretical basis.
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    Tailoring Properties of Hafnium Nitride Thin Film via Reactive Gas-Timing RF Magnetron Sputtering for Surface Enhanced-Raman Scattering Substrates
    (2022-01-01)
    Sucheewa, Nguentra
    ;
    Wongwiriyapan, Winadda
    ;
    Klamchuen, Annop
    ;
    Obata, Michiko
    ;
    Fujishige, Masatsugu
    This study successfully demonstrated the tailoring properties of hafnium nitride (HfN) thin films via reactive gas-timing (RGT) RF magnetron sputtering for surface-enhanced Raman spectroscopy (SERS) substrate applications. The optimal RGT sputtering condition was investigated by varying the duration time of the argon and nitrogen gas sequence. The RGT technique formed thin films with a grain size of approximately 15 nm. Additionally, the atomic ratios of nitrogen and hafnium can be controlled between 0.24 and 0.28, which is greater than the conventional technique, resulting in a high absorbance in the long wavelength region. Moreover, the HfN thin film exhibited a high Raman signal intensity with an EF of 8.5 × 104 to methylene blue molecules and was capable of being reused five times. A superior performance of HfN as a SERS substrate can be attributed to its tailored grain size and chemical composition, which results in an increase in the hot spot effect. These results demonstrate that the RGT technique is a viable method for fabricating HfN thin films with controlled properties at room temperature, which makes them an attractive material for SERS and other plasmonic applications.
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    Simple synthesis, kinetics and thermodynamics of rod-like Cu2(OH)PO4 microparticles and rod-like Cu4O(PO4)2 nanoparticles
    (2020-08-01)
    Kullyakool, Saifon
    ;
    Boonchom, Banjong
    ;
    Chaiseeda, Kittichai
    Rod-like Cu<inf>2</inf>(OH)PO<inf>4</inf> microparticles were synthesized via a simple wet chemical reaction by mixing the solutions of CuSO<inf>4</inf>·5H<inf>2</inf>O and Na<inf>3</inf>PO<inf>4</inf>·12H<inf>2</inf>O at 90 °C for 24 h. Thermal transformation of the prepared Cu<inf>2</inf>(OH)PO<inf>4</inf> microparticles were related to endothermic dehydroxylation and its final decomposed product rod-like Cu<inf>4</inf>O(PO<inf>4</inf>)<inf>2</inf> nanoparticles were obtained. The XRD results indicated that Cu<inf>2</inf>(OH)PO<inf>4</inf> and Cu<inf>4</inf>O(PO<inf>4</inf>)<inf>2</inf> crystallize orthorhombic (space group Pnnm, D<inf>2h</inf> <sup>12</sup>) and triclinic (space group P1‾, C<inf>i</inf> <sup>1</sup>) phases, respectively. The thermal transformation mechanisms from Cu<inf>2</inf>(OH)PO<inf>4</inf> to Cu<inf>4</inf>O(PO<inf>4</inf>)<inf>2</inf> were expressed thought the relation of the graphical shape of isothermal combined with the non-isothermal multi-heating rate equation and kinetic models (P<inf>3/2</inf> and R<inf>2</inf>) to discuss the change of morphologies from microparticles to nanoparticles. Kinetic parameters and triplet thermodynamic functions of activated compound were determined and fully discussed. The obtained data will be useful for academic scientists and industrial researchers to apply these copper phosphates for special applications.