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    Electrical properties of bismuth potassium titanate-strontium titanate ferroelectric ceramics
    (2010-07-30)
    Phetnoi, Prapapim
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    Niemcharoen, Surasak
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    Sutapun, Manoon
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    In this paper, lead-free (Bi<inf>0.5</inf>K<inf>0.5</inf>)TiO<inf>3</inf> ceramics doped with SrTiO<inf>3</inf> was prepared by the conventional solid state reaction method with sintering temperature at 1040°C. The samples were characterized by X-ray diffraction analysis and Scanning Electron Microscopy. The dielectric, ferroelectric properties were also investigated. The results of X-ray diffraction reveal that SrTiO<inf>3</inf> diffuse into the Bi <inf>0.5</inf>K<inf>0.5</inf>TiO<inf>3</inf> lattices to form a solid solution with a pure perovskite structure. After the introduction of SrTiO<inf>3</inf> into Bi<inf>0.5</inf>K<inf>0.5</inf>TiO<inf>3</inf>, the dielectric constant at room temperature (ε<inf>r</inf>) was found to decrease with increasing SrTiO<inf>3</inf>. The broadness of the dielectric constant peak was observed with increasing SrTiO<inf>3</inf> content, especially that of the 0.94Bi <inf>0.5</inf>K<inf>0.5</inf>TiO<inf>3</inf> - 0.06 SrTiO<inf>3</inf> ceramic which exhibited a very broad curve over a wide temperature range. The Bi <inf>0.5</inf>K<inf>0.5</inf>TiO<inf>3</inf> - SrTiO<inf>3</inf> system was expected to be a new and promising candidate for lead-free capacitors.
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    Phase transition behaviour and electrical properties of lead-free (K 0.5Na0.5)NbO3-LiNbO3-LiSbO 3 piezoelectric ceramics
    (2011-05-01) ;
    Niemcharoen, Surasak
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    Sutapun, Manoon
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    ;
    The ternary system of 0.945(K<inf>0.5</inf>Na<inf>0.5</inf>NbO <inf>3</inf>)-(0.055 - x)LiNbO<inf>3</inf>-xLiSbO<inf>3</inf> [0.945KNN-(0.055 - x)LN-xLS]; x = 0.0-0.055 lead-free piezoelectric ceramics was fabricated by the conventional mixed oxide method with normal sintering. The crystal structure was studied by means of X-ray diffraction (XRD). The results of XRD patterns show that complete solid solutions of the mixed phase between the orthorhombic and tetragonal perovskite phase were observed. The DSC and dielectric data show that the amount of LiSbO<inf>3</inf> in K<inf>0.5</inf>Na<inf>0.5</inf>NbO <inf>3</inf>-LiNbO<inf>3</inf> solid solution slightly decreases the paraelectric cubic-ferroelectric tetragonal phase transition (T<inf>C</inf>) to a low temperature. Furthermore, good dielectric and piezoelectric properties were observed at composition, x = 0.03. The polymorphic phase transition between the orthorhombic and tetragonal phases plays a very important role in enhancement of the piezoelectric properties of KNN-LN-LS ceramics. © 2010 Elsevier B.V. All rights reserved.
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    Tetramethyl ammonium hydroxide etchant improvement for aluminum passivation and smooth of silicon surface
    (2019-03-01)
    Suttijalern, Kamonwan
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    Prabket, Jirawat
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    Niemcharoen, Surasak
    This paper purpose to the structural design and improvement of etchant solution for U-shaped Metal-Semiconductor-Metal (UMSM) photodetector fabrication on Al/n-Si/Al with anisotropic wet etching technique, the etchant solutions include tetramethylammonium hydroxide (TMAH), ammonium persulfate (AP) and silicic acid with different concentrations. Experimental design of photodetector structure to optimize the photodetector and improvement conditions of the etching solution by adding AP and silicic acid into the TMAH solution to increase the silicon surface roughness and reduce the rate of etching aluminum as electrodes. For structural design experiments, increasing the exposure area on the U-shaped groove up to 1.73 times. The results from the addition of AP to TMAH solution showed that the silicon surface is smoothness. It has a highest silicon etching rate and the addition of silicic acid to TMAH solution can reduce aluminum and silicon dioxide etching rate. Therefore, this research has the effective condition is 5 wt% TMAH with 7 g/1 AP and 34 g/1 silicic acid added. The results show the silicon surface has smooth about 5 nm and high silicon etch rate including etching aluminum equal to 0.26 μm/hr that suitable for design photodetector in further research.
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    Structure and dielectric properties of Bi0.5K 0.5TiO3-SrTiO3 lead-free ceramics
    (2011-01-01)
    Ruangphanit, Anucha
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    Phetnoi, Prapapim
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    Niemcharoen, Surasak
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    Bismuth potassium titanate - strontium titanate (1-x)Bi<inf>0.5</inf>K <inf>0.5</inf>TiO<inf>3</inf>-(x)SrTiO<inf>3</inf> (BKT-ST) lead-free ceramics when x = 0-0.20 were synthesized by the solid state reaction method with normal sintering. The ferroelectric phase transition was studied by X-ray diffraction (XRD). All compositions showed a single phase perovskite structure with tetragonal symmetry at room temperature and the phase structure transformed from ferroelectric tetragonal - paraelectric cubic in the range of x ≥ 0.10. Dielectric study revealed that the dielectric relaxor behavior was induced with increasing ST and transition temperature (T<inf>m</inf> ε<inf>r max</inf>) of ST-doped BKT had a tendency to decrease with increasing ST. The Bi <inf>0.5</inf>K<inf>0.5</inf>TiO<inf>3</inf>-SrTiO<inf>3</inf> system was expected to be a new and promising candidate for lead-free capacitors. © (2011) Trans Tech Publications.
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    Porous Silicon Formation by Stain Etching on Pyramid Surface in U-Shape MSM Photodetector
    (2024-01-01) ; ;
    Vijafun, Jidapa
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    Suttijalern, Kamonwan
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    Niemcharoen, Surasak
    In this paper, the porous silicon formation on pyramid surface in U-shape MSM photodetector was studied. Stain etching technique was used to prepare porous silicon material. The solution for stain etching contained the mixed solution of hydrofluoric acid (HF), nitric acid (HNO<inf>3</inf>) and deionized water (DI) with ratios 1: 3: 5 and used halogen lamp expouse 30,000 lux between etching for excite porous formation in 2 minutes. Porous silicon was fabricated on pyramid surface in U shape which between metal electrode titanium and aluminum on p-type silicon 20-25 Ω-cm to reduce the reflection of incident light and to increase a photocurrent of MSM photodetector. In the final part of this paper are the comparison physical morhhology and electrical characteristic of porous silicon on pyramid surface in U shape MSM photodetector with pyramid in U-shape MSM photodetector without porous silicon on the surface and planar MSM photodetector. The physical morphology of porous silicon on pyramid surface in U-shape was studied by using scanning electron microscopy (SEM). The electrical characteristic was investigated by using incident light with wave length 635 nm and power 6 mW at bias voltage 10 V. The result of comparison, we found that porous silicon on the surface of pyramid in U-shape MSM photodetector is rougher than pyramid in U-shape MSM photodetector without porous silicon on the surface. The electrical characteristic of porous silicon on pyramid surface in U-shape MSM photodetector respond incident light higher than pyramid in U-shape MSM photodetector without porous silicon on the surface. Therefore the forming porous silicon on the suface of pyramid in U-shape MSM photodetector is appropriate for the fabrication of MSM photodetector with high photocurrent.
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    Non-isothermal kinetics of the thermal decomposition of sodium oxalate Na2C2O4
    (2012-03-01)
    Chaiyo, Nopsiri
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    Niemcharoen, Surasak
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    The thermal transformation of Na<inf>2</inf>C<inf>2</inf>O<inf>4</inf> was studied in N<inf>2</inf> atmosphere using thermo gravimetric (TG) analysis and differential thermal analysis (DTA). Na<inf>2</inf>C<inf>2</inf>O<inf>4</inf> and its decomposed product were characterized using a scanning electron microscope (SEM) and the X-ray diffraction technique (XRD). The non-isothermal kinetic of the decomposition was studied by the mean of Ozawa and Kissinger-Akahira-Sunose (KAS) methods. The activation energies (Eα) of Na<inf>2</inf>C<inf>2</inf>O<inf>4</inf> decomposition were found to be consistent. Decreasing Eα at increased decomposition temperature indicated the multi-step nature of the process. The possible conversion function estimated through the Liqing-Donghua method was 'cylindrical symmetry (R <inf>2</inf> or F<inf>1/2</inf>)' of the phase boundary mechanism. Thermodynamic functions (DH*, DG* and DS*), calculated by the Activated complex theory and kinetic parameters, indicated that the decomposition step is a high energy pathway and revealed a very hard mechanism. © Akadémiai Kiadó, Budapest, Hungary 2011.
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    Enhancing PV system modeling accuracy with the irradiance intensity selection technique
    (2026-06-01)
    Songtrai, Sasiwimon
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    Chinnavornrungsee, Perawut
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    Sriprapha, Kobsak
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    Kobayashi, Tomonao
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    Niemcharoen, Surasak
    This study is a method to improve the accuracy of photovoltaic (PV) power modeling by the irradiance intensity segmentation. The developed model was compared with 2 years of data from PV system in Thailand and the original 1D5P and weight function models to determine accuracy. The results show that by applying the irradiance intensity selection technique with a 1D5P equivalent circuit model improved the accuracy of the proposed model. The proposed method achieved a significantly lower %root mean square error (%RMSE) compared with other models yielding %RMSE values of 0.26% under clear-sky and 2.80% under cloudy conditions. Seasonal evaluation further demonstrated improved prediction accuracy, with the lowest deviation observed during the rainy period, attributed to reduced dust accumulation. A 2 years comparison confirmed the proposed model exhibited the lowest deviation of 0.69%, outperforming conventional PV simulation programs. These findings indicate that irradiance segmentation enhances forecasting performance and provides accurate PV output estimation under real environmental conditions.
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    Preparation of lead zirconate-lead nickel niobate ceramics by the reaction sintering process
    (2009-12-01) ; ;
    Niemcharoen, Surasak
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    Laoratanakul, Pitak
    The perovskite structure of lead zirconate - lead nickel niobate ceramics, (1-x) PbZrO3-xPb(Ni1/3Nb2/3)O3 (PZ - PNN) at x between 0.00-0.50, has been prepared by the reaction-sintering process. The specimens were prepared directly from a mixture of their constituent oxide without any calcination step. The PZ - PNN ceramics could be obtained after 6 h sintering at 1,100-1,250°C. Crystal structure and phase transition of PZ-PNN were investigated by x-ray diffraction (XRD). XRD indicated that the structure of PZ-PNN ceramics is orthorhombic for a composition where x = 0.00, rhombohedral for compositions where x = 0.10 ≤ x ≤ 0.40 and pseudo-cubic for a composition where x = 0.50. The dielectric properties of the ceramics were measured as functions of both temperature and frequency. The results indicated that the transition temperature decreases with increasing PNN concentration. Furthermore, morphology and grain size evolution have been determined via a scanning electron microscope (SEM). Copyright © Taylor & Francis Group, LLC.
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    Influence of Pb(In1/2Nb1/2)O3 on the phase transitions, electrical, and thermal properties of a PbZrO3 ceramic
    (2011-10-01) ; ;
    Niemcharoen, Surasak
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    The solid solution of a (1-x)PbZrO<inf>3</inf>-xPb(In<inf>1/2</inf>Nb <inf>1/2</inf>)O<inf>3</inf> (PZ-PIN) system, with x=0.00-0.50, was synthesized using the wolframite precursor method. The effects of the PIN content on the crystal structure, and the electrical and thermal properties of a PbZrO <inf>3</inf> ceramic were investigated using X-ray diffraction, dielectric spectroscopy, hysteresis measurement, and differential scanning calorimetry techniques. Furthermore, the morphology and grain size were determined using scanning electron microscopy. The results indicated that the pure perovskite phase was obtained for all compositions, and the solid solution, PZ-PIN, changed from orthorhombic to rhombohedral symmetry when the amount of PIN increased. A ferroelectric intermediate phase began to appear between the paraelectric and the antiferroelectric phases of pure PZ, with increasing PIN content. The temperature range width of the ferroelectric phase also increased continuously with increasing PIN. At room temperature, the polymorphic phase transition (PPT) was identified from the orthorhombic to the rhombohedral phase in (1-x)PZ-xPIN at the composition, x=0.40. The ceramics (x=0.40) with PPT close to room temperature exhibited excellent electrical properties (ε<inf>rmax</inf>= 33240 and P<inf>r</inf>=26.94 μC/cm<sup>2</sup>). © 2011 The American Ceramic Society.
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    The phase evolution with temperature in 0.94PbZrO3-0. 06Pb(Mg1/2W1/2)O3 antiferroelectric ceramic
    (2010-09-10)
    Charoonsuk, Piyanut
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    Niemcharoen, Surasak
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    The perovskite structure of the lead zirconate-lead magnesium tungstate ceramic, 0.94PbZrO<inf>3</inf>-0.06Pb(Mg<inf>1/2</inf>W<inf>1/2</inf>)O <inf>3</inf> (0.94PZ-0.06PMW), was prepared by the wolframite precursor method. The phase evolution with temperature in the 0.94PZ-0.06PMW ceramic was investigated, with dielectric permittivity, differential scanning calorimetry and polarization measurements. The ceramic was in the antiferroelectric phase when below 177 °C, based on dielectric measurement, and an intermediate phase was detected between 177 and 219 °C. Evidence from ferroelectric data was found to suggest that this intermediate phase is ferroelectric. © 2010 Elsevier B.V. All rights reserved.