• Title/Summary/Keyword: X-ray diffraction patterns

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Structural and Optical Properties of CdS Thin Films Deposited by R.F. Magnetron Sputtering

  • Hwang, Dong-Hyeon;An, Jeong-Hun;Son, Yeong-Guk
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.02a
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    • pp.149-149
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    • 2011
  • CdS films were deposited on glass substrates by R.F. magnetron sputtering method and the films were annealed at various substrate temperatures ranging from room temperature to $300^{\circ}C$. Structural properties of the films were studied by X-ray diffraction analysis. The structural parameters as crystallite size have been evaluated. The crystallite sizes were found to increase, and the X-ray diffraction patterns were seen to sharpen by increasing substrate temperatures. X-ray diffraction patterns of these films indicated that they contain both cubic (zincblende) and hexagonal (wurtzite) structures as a mixture. Optical properties of the films were measured at room temperature by using UV/VIS spectrometer in the wavelength range of 190 to 1100nm and optical absorption coefficients were calculated using these data. The energy gap of the films was found to decrease, and the band edge sharpness of the optical absorption was seen to oscillate by annealing. The results show that heat treatments under optimal annealing condition can provide significant improvements in the properties of CdS thin films.

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An Study on the Structure of Maghemite(${\gamma}$-Fe$_2$O$_3$) I -Rietveld Analysis of Powder XRD Patterns- (마게마이트(${\gamma}$-Fe$_2$O$_3$)대한 연구 I -분말 X-선 회절무늬의 Rietveld 분석-)

  • 신형섭
    • Journal of the Korean Ceramic Society
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    • v.35 no.10
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    • pp.1113-1119
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    • 1998
  • Crystal structure of needle-shaped maghemite(${\gamma}$-{{{{ { {Fe }_{2 }O }_{3 } }}) has been studied by the Rieveld analysis of powder X-ray diffraction patterns. The tetragonal space group P41,.3212 and cubic space group P41,.32 have been have been used for the refinement of X-ray diffraction patterns. The crystal system of maghemite is closed to tetragonal more than cubic. The tetragonal lattice parameters are a=8.3460$\AA$ and c=25.034$\AA$ The standard X-ray diffraction pattern of the tetragonal maghemite analyzed with space group P41,.3212 is proposed.

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Effects of Cereal Powders with Dietary Fibers on Retrogradation Properties of Jeungpyun, a Korean Traditional Fermented Rice Cake

  • Park, Mie-Ja;Kim, Hye Young L.
    • Journal of Environmental Health Sciences
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    • v.29 no.4
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    • pp.48-54
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    • 2003
  • This study investigated retrogradation properties of Jeungpyun substituted for cereals with dietary fibers of 60% of brown rice, and barley. Quality changes during storage periods of the functional Jeungpyun, were studied using $\alpha$-amylase iodine enzyme digestion methods, X-ray diffraction patterns, and differential scanning calorimetry (DSC). The barley substituted samples showed significantly lower retrogrdation rates than those of control when examined by $\alpha$-amylase method. The Relative crystallity by X-ray diffraction patterns had typical A type in all samples with appealing big crystallity around its diffraction angle 23$^{\circ}$degrees as storage periods were increased. The brown rice and barley Jeunpyun made smaller crystallity than that of control, representing slower retrogradation rates. The batter controls had significantly lower ΔH than the other compared samples when measured by DSC, but had significantly higher ΔH after 30 days of storage, implying that the control required more energy for regelatinization after the 30 days of storage.

Studies on Thermal Decomposition of Barium Titanyl Oxalate by Factor Analysis of X-Ray Diffraction Patterns

  • Seungwon Kim;Sang Won Choi;Woo Young Huh;Myung-Zoon Czae;Chul Lee
    • Bulletin of the Korean Chemical Society
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    • v.14 no.1
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    • pp.38-42
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    • 1993
  • Factor analysis was applied to study the thermal decomposition of barium titanyl oxalate (BTO) which is used as the precursor of barium titanate. BTO was synthesized in $H_2O$ solvent and calcined at various temperatures. The X-ray diffraction patterns were obtained to make the data matrix of peak intensity vs. 2${\theta}$. Abstract factor analysis and target transformation factor analysis were applied to this data matrix. It has been found that the synthesized BTO consists of the crystals of $BaC_2O_4{\cdot}0.5H_2O\;and\;BaC_2O_4{\cdot}2H_2O$ as well as the amorphous solid of TiO-oxalate. The results also indicate that the BTO was transformed via $BaCO_3\;to\;BaTiO_3\;and\;Ba_2TiO_4$ during the thermal decomposition.

A Study on the Precursor of $BaTiO_3$ Synthesized in Water (수용액계에서 합성한 $BaTiO_3$의 선구물질에 관한 연구)

  • Kim, Seungwon;Huh, Woo Young;Lee, Chul
    • Analytical Science and Technology
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    • v.5 no.4
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    • pp.409-415
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    • 1992
  • Factor analysis was applied to X-ray diffraction patterns of the precursor of $BaTiO_3$. For that purpose, the precursor was synthesized in water solvent system using $Ba(NO_3)_2$ and $TiO(NO_3)_2$ as the starting materials and calcined at various temperatures. The samples obtained from the various calcined temperatures were analyzed by the X-ray diffractometer. Factor analysis was applied to the intensity data of the X-ray diffraction patterns. As the results, three factors were found and they were found to be $BaCO_3$, $BaTiO_3$ and $Ba_2TiO_4$. The relative concentrations of the three components were estimated during calcination.

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Development of Thermal Sensor Devices in the $BaTiO_3$ Systems ($BaTiO_3$계 박막형 열전센서소자 개발)

  • Song, Min-Jong
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.05d
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    • pp.100-104
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    • 2003
  • $BaTiO_3$ ceramic thin films were manufactured by rf/dc magnetron sputter technique. We have investigated crystal structure, surface morphology and PTCR(positive-temperature coefficient of resistance) characteristics of the specimen depending on second heat-treatment temperatures. Second heat treatments of the specimen were performed in the temperature range of 400 to $1350^{\circ}C$. X-ray diffraction patterns of $BaTiO_3$ thin films show that the specimen heat treated below $600^{\circ}C$ is an amorphous phase and the one heat treated above $1100^{\circ}C$ forms a poly-crystallization. In the specimen heat-treated at $1300^{\circ}C$, a lattice constant ratio (c/a) was 1.188. Scanning electron microscope(SEM) image of $BaTiO_3$ thin films of the specimen heat treated in between 900 and $1100^{\circ}C$ shows a grain growth. At $1100^{\circ}C$, the specimen stops grain-growing and becomes a poly-crystallization.

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Effects of In Vitro Degradation on the Weight Loss and Tensile Properties of PLA/LPCL/HPCL Blend Fibers

  • Yoon Cheol Soo;Ji Dong Sun
    • Fibers and Polymers
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    • v.6 no.1
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    • pp.13-18
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    • 2005
  • PLA/LPCL/HPCL blend fibers composed of poly (lactic acid) (PLA), low molecular weight poly ($\varepsilon$-caprolactone) (LPCL), and high molecular weight poly ($\varepsilon$-caprolactone) (HPCL) were prepared by melt blending and spinning for bioab­sorbable filament sutures. The effects of blending time and blend composition on the X-ray diffraction patterns and tensile properties of PLA/LPCL/HPCL blend fibers were characterized by WAXD and UTM. In addition, the effect of in vitro degra­dation on the weight loss and tensile properties of the blend fibers hydrolyzed during immersion in a phosphate buffer solu­tion at pH 7.4 and 37$^{\circ}C$ for 1-8 weeks was investigated. The peak intensities of PLA/LPCL/HPCL blend fibers in X-ray diffraction patterns decreased with an increase of blending time and LPCL contents in the blend fibers. The weight loss of PLA/LPCL/HPCL blend fibers increased with an increase of blending time, LPCL contents, and hydrolysis time while the tensile strength and modulus of the blend fibers decreased. The tensile strength and modulus of the blend fibers were also found to be increased with an increase of HPCL contents in the blend fibers. The optimum conditions to prepare PLA/LPCL/HPCL blend fibers for bioabsorbable sutures are LPCL contents of $5 wt\%, HPCL contents of $35 wt\%, and blending time of 30 min. The strength retention of the PLA/LPCL/HPCL blend fiber prepared under optimum conditions was about $93.5\% even at hydrolysis time of 2 weeks.

A Study on the Microstructure and Thermal Sensor Devices of the Thin Films in the $BaTiO_3$ Systems ($BaTiO_3$계 세라믹의 미세구조와 열전센서에 관한 연구)

  • Song, Min-Jong
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.05b
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    • pp.135-139
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    • 2005
  • Thin films of $BaTiO_3$ system were prepared by radio frequency(rf)/dc magnetron sputtering method. We have investigated crystal structure, surface morphology and PTCR(positive-temperature coefficient of resistance) characteristics of the specimen depending on second heat-treatment temperatures. Second heat treatments of the specimen were performed in the temperature range of 400 to $1350^{\circ}C$. X-ray diffraction patterns of $BaTiO_3$ thin films show that the specimen heat treated below $600^{\circ}C$ is an amorphous phase and the one heat treated above $1100^{\circ}C$ forms a poly-crystallization. In the specimen heat-treated at $1300^{\circ}C$, a lattice constant ratio (c/a) was 1.188. Scanning electron microscope(SEM) image of $BaTiO_3$ thin films of the specimen heat treated in between 900 and $1100^{\circ}C}$ shows a grain growth. At $1100^{\circ}C$, the specimen stops grain-growing and becomes a poly-crystallization.

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Comparison on Retrogradation Properties of Cowpea and Mung Bean Starch Gels (동부와 녹두전분 Gel의 노화특성 비교)

  • Yoon, Gae-Soon
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.21 no.6
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    • pp.672-676
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    • 1992
  • Retrogradation properties of cowpea and mung bean starch gels were investigated by rate of retrogradation, X-ray diffraction patterna and syneresis of gels. Retrogradation time constant of mung bean starch gel(30%) by Avrami equation had a similar value to that of cowpea starch gel. X-ray diffraction patterns of the two retrograded starch gels(10%) were B-type. The extent of retrogradation determined by syneresis showed that cowpea starch gel was a little larger than that of mung bean starch gel(6~10%).

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Characterization Of YBCO HTSC-Thick film With addiction of $CeO_2$ ($CeO_2$첨가에 따른 YBCO고온초전도 후막의 특성)

  • 윤기웅;임성훈;홍세은;강형곤;한용희;한병성
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.07a
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    • pp.239-242
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    • 2000
  • To fabricate YBa$_2$Cu$_3$O$_{x}$ thick film using diffusion process, $Y_2$BaCuO$_{5}$ and BaO+CuO as the material of substrate and the doping material were selected. CeO$_2$ in the doping material was mixed. As another doping material, YBa$_2$Cu$_3$O$_{x}$ was prepared for the comparison with BaO+CuO doping material. Each doping material was patterned on $Y_2$BaCuO$_{5}$ substrate by the screen printing method and then was annealed above peritectic reaction temperature of YBCO with a few step. It could be observed by X-ray diffraction patterns and SEM photographs that through the diffusion process of the $Y_2$BaCuO$_{5}$ and BaO+CuO, the YBa$_2$Cu$_3$O$_{x}$ phase was formed. With an amout of addition of CeO$_2$, the thickness of a formed YBa$_2$Cu$_3$O$_{x}$ decreased. x/ decreased.

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