Thanomngam, Pitiporn
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Thanomngam, Pitiporn
Alternative Name
Thanomngam, P.
Thanomngam, Pittiporn
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Email
pitiporn.th@kmitl.ac.th
23 results
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Item type:Publication, Investigation of structural properties of CuPc/TiO2 nanocomposites(2010-02-05); Structural properties of hybrid nanocomposites based on TiO<inf>2</inf> nanostructures and Copper phthalocyanine (CuPc) were investigated. The composites were prepared by mixing TiO<inf>2</inf> nanoparticle (TNP) and nanotube (TNT) with CuPc suspension. The precipitated composites were obtained by centrifuged and dried processes. Structural properties of the composites were evaluated by mean of Raman Spectroscopy and X-ray Absorption Fine Structure (XAFS). The results implied that CuPc has interatomic distance of C atoms in the second shell are decreased when CuPc is in the hybrid composites. © (2010) Trans Tech Publications. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, First-principles investigation on elastic constants of TiN under high pressure(2013-10-29); Sarasamak, KanoknanElastic constants of NaCl-type TiN under pressure were investigated by first-principles calculations within both local density approximation (LDA) and Perdew-Burke-Ernzerhof generalized-gradient approximation (PBE-GGA). At ambient pressure, the calculated lattice parameter, bulk modulus, and elastic constants of NaCl-type TiN are in well agreement with other available values. Under pressure, all elastic constants, C<inf>11</inf>, C<inf>12</inf>, and C<inf>44</inf>, are found to increase with pressure. C<inf>11</inf>, which is related to the longitudinal distortion, increases rapidly with pressure while C<inf>12</inf> and C<inf>44</inf> which are related to the transverse and shear distortion, respectively, are much less sensitive to pressure. © (2013) Trans Tech Publications, Switzerland. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Band gap prediction of the alloying halide perovskites using GW compare to DFT-1/2 method(2020-10-26); The outstanding optoelectronic properties of methylammonium halide perovskites, including the tunable spectral absorption range, high carrier mobilities and low carrier recombination rates, make these materials are interesting for a decade year. In my works, a first-principle calculation based on non-local van der Waals-corrected Density Functional Theory (vdW-DFT) is performed to investigate high accuracy atomic structures and their properties of the alloying halide perovskites (CH3NH3PbIxBr1-x). While DFT generally underestimates the band gap for practically semiconductors and insulators, it provided a surprising accurate value for methylammonium halide perovskites. Unfortunately, this performance is not existing to another hybrid halide perovskite. The relativistic GW approximation is known to be a better-provided band gap more accurately, but at an extremely high computational cost were applied to the study. Here we also report the efficiency and accuracy of the bandgap calculations of methylammonium halide perovskites by using the self-consistent quasiparticle GW method (scGW) incorporated with the spin-orbit coupling comparing to recent develops DFT-1/2 method. The latter computational scheme provides accurate band gaps with the precision of the scGW method with no more computational cost than standard DFT. This method can solve the band gap problem by correcting the half-hole/half-electron occupation in the pseudopotentials. This work yields the possibility of the band gap prediction of alloying halide perovskite material (CH3NH3PbIxBr1-x) that good for optoelectronic design such as planar dye solar cell. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, First-Principles Investigation on Structural and Electronic Properties of Ferromagnetic Fe2P4O12(2015-06-23); Structural and electronic properties of Fe<inf>2</inf>P<inf>4</inf>O<inf>12</inf> have been investigated using first-principles calculation technique. The results indicated that the Fe<inf>2</inf>P<inf>4</inf>O<inf>12</inf> structure is monoclinic of C<inf>2</inf>/c with lattice parameters of a = 12.228 Å, b = 8.530 Å, c = 9.835 Å and β = 118.67°. Two nonequivalent octahedral FeO<inf>6</inf> from the calculation have an average Fe-O distance of 2.143 Å. Both FeO<inf>6</inf> are dominated by covalent interactions assigned to Fe<inf>3d</inf> and O<inf>2p</inf> at the valent electronic states. The DOS calculation gives well explanation on its half-metallic ferromagnetic property. These results are in very good agreement with the previous experimental reports. © 2015 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Study on optical and electronic properties of Sn-doped ZnPc(2013-10-29); ; Sn doped ZnPc films were deposited on intrinsic Si and glass substrates by organic source thermal co-evaporation technique with different deposition rates. Optical properties and electronic structure were characterized by UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS) respectively. The UV-Vis results showed that phase transition of ZnPc from α- phase to β-phase occurred when Sn:ZnPc deposition rate is 0.3:0.7 or higher. XPS results indicated that the outer s electron of Sn atom is transferred to the ZnPc. Broadening of the C 1s spectra is observed with the increasing of Sn deposition rate. This broadening corresponds to the change of molecular environment surrounding carbon atoms in the Sn-doped ZnPc films. © (2013) Trans Tech Publications, Switzerland. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Pressure Dependence of Structural and Elastic Properties of Na2O: First-Principles Calculations(2022-01-01); The effect of high pressures, up to 40 GPa, on the structural and elastic properties of sodium oxide in cubic structure (c-Na<inf>2</inf>O) were investigated by first-principles calculations. The generalized gradient approximation (GGA) with the Perdew-Burke-Ernzerhof (PBE) functional was employed in the calculations. The calculated structural and elastic properties at zero pressure are consistent with the available results. The pressure dependence of structural and elastic properties was presented and discussed in detail. Under pressure, the elastic constants satisfy the Born criteria, indicating that c-Na<inf>2</inf>O is mechanically stable. Moreover, other elastic properties such as bulk modulus (B), shear modulus (G), and Young's modulus (E) under pressures were analyzed. Furthermore, the B/G values tend to increase with the increasing pressure, which means that pressure can improve the ductility of c-Na<inf>2</inf>O. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, First-principles study of antisite defects in orthorhombic PbZrO 3(2014-09-02); T-Thienprasert, JirarojFirst-principles calculations based on density functional theory (DFT) within local density approximation were employed to investigate the antisite defects, including Pb<inf>Zr</inf> and Zr<inf>Pb</inf>, in orthorhombic PbZrO<inf>3</inf> by determining their defect formation energies. The formation energies of antisite defects were then compared with those of other dominant defects, i.e., lead Pb, zirconium Zr, and oxygen O vacancies to examine the likelihood of their existence. Our results revealed that Pb<inf>Zr</inf> defect in neutral charge state is the most dominant defect under O-rich or oxidizing condition in agreement with the previous work. In addition, there is a little structural relaxation when the Zr atom is replaced by Pb atom to form Pb <inf>Zr</inf> defect in neutral charge state. In opposite, under O-poor or reducing condition, the formation energies of antisite defects are quite high and higher than those of vacancy defects. This suggests that antisite defects are unlikely to form under reducing condition. © 2014 Taylor & Francis Group, LLC. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, First principles study on structural and electronic properties of Li, Na and K - Intercalated zinc phthalocyanine(2018-01-01); Recently, alkali metals doped zinc phthalocyanine (ZnPc) was found to be an effective method for tuning electronic properties of ZnPc. In this research, the effect of alkali metal atoms (Li, Na, and K) intercalation on structural and electronic properties of ZnPc in β structure was investigated by first principles calculations based on density function theory (DFT). The generalized gradient approximation (GGA) is used to describe the exchange-correlation with the projector-augmented wave (PAW) method. The calculated lattice constants, bond lengths and bond angles of pristine ZnPc are in good agreement with other calculations and experimental data. The calculated band gap energy of pristine ZnPc is found to be 1.327 eV. The lattice constants, molecular arrangement, bond lengths and bond angles are sensitive to intercalating alkali metal atoms. It was found that intercalating alkali metal atoms induce significant changes in the band gap energy of ZnPc. The changes in band gap energy with intercalating alkali metal atoms are discussed. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, First-principles study of Bi and Al in orthorhombic PbZrO3(2016-04-01); - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Surface morphology and structural investigation of TiN nanocrystal thin films grown with different N2 concentration(2013-02-19);