Sukkha, Usa

Preferred name

Sukkha, Usa

Main Affiliation

KMITL Prince of Chumphon Campus

usa.suk@kmitl.ac.th

Now showing 1 - 5 of 5

Some of the metrics are blocked by your
consent settings
Synchrotron-based NEXAFS analysis of thermal-treated diamond-like carbon films
(2020-10-01)
Chunjaemsri, Thanun
;
Chanlek, Narong
;
Sukkha, Usa
;
Nakajima, Hideki
;
Rujirawat, Saroj
Diamond-like carbon (DLC) film properties are known to vary with important factors such as the ratio of sp3 to sp2 hybridization, film thickness, and contaminations. In this work, the carbon bonding contents in DLC thin films, thermal-treated with various temperatures between room temperature to 250 °C, were studies by near-edge X-ray absorption fine structure (NEXAFS), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. From NEXAFS measurements, the sp3/sp2 ratios of DLC films were found to be unaffected by the thermal treatments. The results indicate that thermal treatment below 250 °C does not affect the carbon bonding contents in DLC thin film.
Some of the metrics are blocked by your
consent settings
Local structure elucidation and reaction mechanism of light naphtha aromatization over Ga embedded H-ZSM-5 zeolite: Combined DFT and experimental study
(2020-10-15)
Wongnongwa, Yutthana
;
Kidkhunthod, Pinit
;
Sukkha, Usa
;
Pengpanich, Sitthiphong
;
Thavornprasert, Kaew arpha
Local structures and mechanisms for n-pentane aromatization on Ga embedded H-ZSM-5 zeolite (Ga/ZSM-5) were elucidated using Synchrotron-based X-ray absorption spectroscopy (XAS) and density functional theory (DFT) calculations to understand the role of Ga/ZSM-5 zeolite in aromatics synthesis. XAS data suggests that Ga ligates with four oxygen or four hydrogen atoms. Catalytic tests results suggest that conversion by Ga/ZSM-5 catalyst cannot occur via C6–C8 non-aromatic intermediates, while the availability of Ga metal sites promotes the aromatization of C2 and C3 species. Therefore, conversion of n-pentane to benzene or toluene comprises four steps, i) cracking, ii) GaH<inf>2</inf> activation, iii) cyclization, and iv) dehydrogenation. Our model predicts the key intermediate in n-pentane aromatization on Ga/ZSM-5 zeolite to be a five-membered Ga-C4 ring structure. The ring undergoes expansion to form a seven-membered Ga-C6 ring. Moreover, we discuss thermodynamics and kinetic results for the benzene and toluene formation pathways. Our results provide new finding for the role of Ga/ZSM-5 zeolites in n-pentane aromatization processes.
Some of the metrics are blocked by your
consent settings
Effect of thermal annealing on the structure of LiCoO2 powders prepared by co-precipitation method
(2021-12-01)
Khejonrak, Awadol
;
Chanlek, Narong
;
Sukkha, Usa
;
Triamnak, Narit
;
Chirawatkul, Prae
Lithium cobalt oxide (LiCoO<inf>2</inf>) powder was prepared by co-precipitation method and annealed at different temperatures of between 300 and 700 °C. The effect of annealing temperature and effect washing process with deionized water on the crystal structures of the prepared LiCoO<inf>2</inf> powders were thoroughly studied by Synchrotron powder X-Ray Diffraction (Syn-XRD), X-ray Absorption Spectroscopy (XAS), Dispersive Raman Microscopy (Raman) techniques. The change in chemical composition as a function of annealing temperature was also investigated by X-ray Photoelectron Spectroscopy (XPS) technique. The crystal structural results identified the phase evolution of the prepared LiCoO<inf>2</inf> powders upon heat treatment. The formation of HT-LiCoO<inf>2</inf> phase was observed at annealing temperature as low as 300 °C.
Some of the metrics are blocked by your
consent settings
Effect of Ba0.93Ca0.04La0.03Sn0.1Ti0.9O3 addition on structural and electrical properties of lead-free 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 piezoelectric ceramics
(2025-12-01)
Kantha, Puripat
;
Unruan, Muangjai
;
Tunkasiri, Tawee
;
Pengpat, Kamonpan
;
Sukkha, Usa
The doping of other materials into the structure of BCZT ceramics can improve the electrical properties. The lead-free piezoelectric ceramics in the (1-x)BCZT–xBCLST binary system, where x = 0.00, 0.01, 0.03, 0.05, and 0.07 mol, were synthesized using a two-step mixed oxide method. Initially, pure phases of 0.5Ba(Zr<inf>0.2</inf>Ti<inf>0.8</inf>)O<inf>3</inf>-0.5(Ba<inf>0.7</inf>Ca<inf>0.3</inf>)TiO<inf>3</inf> (BCZT) and Ba<inf>0.93</inf>Ca<inf>0.04</inf>La<inf>0.03</inf>Sn<inf>0.1</inf>Ti<inf>0.9</inf>O<inf>3</inf> (BCLST) powders were separately prepared by mixed oxide and conventional solid-state reaction methods. X-ray diffraction patterns and Ti K-edge X-ray Absorption Near-Edge Structure (XANES) spectra revealed structural distortions in BCLST-doped ceramics. The electrical properties including dielectric, piezoelectric, and ferroelectric properties were evaluated. Besides, the dielectric constant and dielectric loss at room temperature of BCZT–BCLST ceramics were enhanced with increasing BCLST content. The dielectric properties at room temperature improved with increasing BCLST concentration from x = 0.00 to x = 0.03 mol, with the maximum dielectric constant rising from 1408 to 2552—an increase of approximately 81 %. The hysteresis P–E loop of BCZT–BCLST ceramics exhibited a slim loop, with a maximum remanent polarization (P<inf>r</inf>) of 7.22 μC/cm2 observed at x = 0.03 mol. The optimal doping condition for BCLST in BCZT ceramics was found at 0.03 mol, yielding the highest piezoelectric coefficient (d<inf>33</inf>) of 235 pC/N—an improvement of approximately 9 % compared to the undoped sample (x = 0.00).
Some of the metrics are blocked by your
consent settings
Thermally induced phase transition and dielectric relaxation in lead-free BaTi0.94Sn0.06O3 Ceramics: Insights from in-situ XRD and XAS
(2025-11-01)
Sukkha, Usa
;
Chanlek, Narong
;
Kidkhunthod, Pinit
;
Kolodiazhnyi, Taras
;
Vittayakorn, Wanwilai
Lead-free BaTi<inf>0.94</inf>Sn<inf>0.06</inf>O<inf>3</inf> (BTS) ceramics were synthesized using the conventional solid-state reaction method to investigate thermally induced phase transitions and dielectric relaxation phenomena. A combination of in-situ X-ray Diffraction (XRD) and in-situ Synchrotron X-ray Absorption Spectroscopy (XAS) was employed to examine phase transitions across the temperature range of 200–400 K. The results reveal sequential phase transitions: rhombohedral-orthorhombic (R + O) at 200 K, orthorhombic (O) at 250–300 K, tetragonal (T) at 325–359 K, and tetragonal-cubic (T + C) at 373–400 K. Dielectric measurements highlight an anomalous relaxation behavior at 70–160 K, attributed to domain wall freezing. This phenomenon follows Vogel-Fulcher behavior, with an activation energy of 14 meV, a freezing temperature of 82 K, and an attempt frequency of 4.7 × 106 Hz. X-ray Photoelectron Spectroscopy (XPS) analysis reveals oxygen deficiency on the surface of the BTS ceramic, resulting in the coexistence of Ti3+/Ti4+ and Sn2+/Sn4+ oxidation states. These defects significantly influence the dielectric and phase transition properties. This study provides comprehensive insights into the interplay between local structural changes and phase transition mechanisms in BTS ceramics. By employing a multi-technique approach, it advances the understanding of dielectric and ferroelectric behaviors, positioning BTS ceramics as promising candidates for lead-free dielectric and ferroelectric device applications.

Sukkha, Usa

Filters

Settings

Sort By

Results per page