• Title, Summary, Keyword: X-ray powder diffraction

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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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X-Ray Diffraction Patterns and Acid Consuming Capacity of Aluminum Hydroxide Gel. (수산화알루미늄.겔의 X선회절상과 제산도)

  • 조문혜
    • YAKHAK HOEJI
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    • v.8 no.2
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    • pp.37-44
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    • 1964
  • The relationships involving acid-consuming capacity and X-ray powder diffraction patterns of aluminum hydroxide gel were studied. The aging of antacid efficacy of aluminum hydroxide gel has also been characterized by using X-ray powder diffraction. The acid-consuming capacity decreased with progress of crystallization from amorphous alumino gel, and it was found that aged product at 80.deg. C had crystal structure of bohmite (.alpha.-Al.sub 2/O$_{2}$(OH)$_{2}$). It was also noted that the rate of aging decreased with decreasing pH of aluminum hydroxide gel.

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Synchrotron X-ray Powder Diffraction Study of CFC-13 Loaded Zeolite LSX (제올라이트 LSX에서의 CFC-13 분자체 흡착에 관한 결정학적 연구)

  • Lee, Yong-Jae;Lee, Jong-Won;Yoon, Ji-Ho
    • Journal of the Mineralogical Society of Korea
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    • v.21 no.3
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    • pp.307-312
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    • 2008
  • Rietveld analysis using synchrotron X-ray powder diffraction data collected at 15 K reveals that CFC-13 ($CF_{3}Cl;$ chlorotrifluoromethane) sorbed on Na,K-LSX binds through fluorine to sodium ions around the single 6-ring aperture in the supcrgage.

The Structure Determination of La2/3-xLi3x1/3-2xTiO3 by the Powder Neutron and X-ray Diffraction

  • Kang, Eun-Tae;Kwon, Young-Jean
    • Journal of the Korean Ceramic Society
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    • v.40 no.6
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    • pp.513-518
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    • 2003
  • La/sub 2/3-x/Li/sub 3x/□/sub 1/3-2x/TiO₃ compounds with x=0.13 and 0.12 were prepared by slow cooling (x=0.13) and rapid quenching (x=0.12) into the liquid nitrogen after sintering at 1350℃ for 6 h. Their crystal structure has been determined by Rietveld refinement of both the powder neutron and X-ray diffraction data. From neutron diffraction data, we found that the main phase was not tetragonal (P4/mmm), but trigonal (R3cH). The refinement of neutron diffraction for the slow cooled samples were in a good agreement with a new model; a mixture of trigonal (R3cH, 45.7 wt%), tetragonal (p4/mmm, 37.0 wt%), and Li/sub 0.57/Ti/sub 0.86/O₂(pbnm, 17.2 wt%), but the quenched sample was found not to contain tetragonal (p4/mmm). X-ray diffraction data couldn't be well fitted because of the Poor scattering factor of lithium ions and the similar reflection patterns among trigonal (R3cH), tetragonal (p4/mmm), and cubic (Pm3m). We also knew that one transport bottlenecks is destroyed by one La vacancy in the case of trigonal (R3cH).

High Pressure X-Ray Diffraction Study on a Goethite using Synchrotron Radiation (방사광을 이용한 괴타이트에 대한 고압 X-선 회절연구)

  • 김영호;이지은
    • Journal of the Mineralogical Society of Korea
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    • v.10 no.2
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    • pp.75-81
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    • 1997
  • High pressure X-ray diffraction study was carried out on a natural FeO(OH)-goethite to investigate its compressibility at room temperature. Energy dispersive X-ray diffraction method was employed using Mao-Bell type diamond anvil cell with Synchrotron Radiation. MgO powder was compressed together with goethite for the high pressure determinations. Bulk modullus was determined to be 147.9 GPa by the Birch-Murnaghan equation of state under assumption of K0' of 4. This value was subjected to compare with its structural analogs and related materials.

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Synthesis, Structures and Properties of Two Metal-organic Frameworks Derived from 3-Nitro-1,2-benzenedicarboxylic Acid

  • Xu, Wen-Jia;Zhang, Ling-Yu;Tang, Jin-Niu;Wang, Dai-Yin;Pan, Gang-Hong;Feng, Yu
    • Bulletin of the Korean Chemical Society
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    • v.34 no.8
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    • pp.2375-2380
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    • 2013
  • Two metal-organic frameworks based on the connectivity co-effect between rigid benzenedicarboxylic acid and bridging ligand have been synthesized $[Zn_2(3-NO_2-bdc)_2(4,4'-bpy)_2H_2O]_n$ (1), $[Co(3-NO_2-bdc)(4,4'-bpy)H_2O]_n$ (2) (where $3-NO_2-bdcH_2$ = 3-nitro-1,2-benzenedicarboxylic acid, 4,4'-bpy = 4,4'-bipyridine). The two novel complexes were characterized by IR spectrum, elemental analysis, fluorescent properties, thermogravimetric analysis, single-crystal X-ray diffraction and powder X-ray diffraction (PXRD). X-ray structure analysis reveals that 1 and 2 are two-dimensional (2D) network structures. Complex 1 and complex 2 belong to triclinic crystal with P-1 space group. The luminescence measurements reveal that two complexes exhibit good fluorescent emissions in the solid state at room temperature. Also, thermal decomposition process and powder X-ray diffraction of complexes were investigated.

Study on the Orientation of Particles in Tablets (정제내부의 입자배열에 관한 연구)

  • Sohn, Young-Taek
    • Journal of Pharmaceutical Investigation
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    • v.21 no.3
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    • pp.125-132
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    • 1991
  • Using X-ray crystallography powder diffraction, the quantitative representation method of preferred orientation of particles ill tablets was developed. Selected faces of a tablet. the upper surface and faces cut parallel and normal to the upper surface, were presented to an X-ray beam and X-ray diffraction patterns for these faces were measured. The effects of particle size. tableting pressure, and particle form on the preferred orientation were also investigated. It was also recognized that the degree of anisotropy in terms of capping tendency was influenced by the preferred orientation of particles in tablets.

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The Synthesis of Maghemite and Hematite Nanospheres

  • Dar, Mushtaq Ahmad;Ansari, Shafeeque G.;Wahab, Rizwan;Kim, Young-Soon;Shin, Hyung-Shik
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • pp.472-473
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    • 2006
  • Maghemite and hematite nanospheres were synthesized by using the Sol-gel technique. The structural properties of these nanosphere powders were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), and pore size distribution. Hematite phase shows crystalline structures. The mean particle size that resulted from BET and XRD analyses were 4.9 nm and 2 nm. It can be seen from transmission electron microscopy that the size of the particles are very small which is in good agreement with the FESEM and the X-ray diffraction. The BET and pore size method were employed for specific surface area determination.

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Application of Quantitative X-ray Diffraction Analysis for Unburned Coal Content on Coke-Char-Sinter Mixtures (고온에서 발생한 코크스-미연소탄-소결광의 혼합물 중 미연소탄의 정량화를 위한 분말 X-선 회절법 적용)

  • 김재명;정진경;김성만;허완욱;김형순
    • Journal of the Korean Ceramic Society
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    • v.40 no.5
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    • pp.481-487
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    • 2003
  • A technique for determination of proportions of char, coal ana coke is needed in order to monitor pulverized coal injection performance in operating blast furnace. Quantitative X-ray powder diffraction analysis can be applied to the problem providing that structural information on carbonaceous materials, coal, char, coke and their mixture are known. Chars were prepared from a coal at different temperatures (1000∼1400$^{\circ}C$) and were characterised by X-Ray powder Diffraction (XRD). The XRD result gave crystallite size (height Lc and diameter, La), aromaticity, number of (002) plane in carbon, and d-spacing. As a result, with increasing heat treat temperature of char, Lc$_{(002)}$, La$_{(10)}$ and number of (002) plane in carbon were increased, and d-spacing and FWHM(Full With Half Maximum) were decreased. Result of prediction of amount of char from the mixtures (char, coke and ore) based on the Lc$_{(002)}$ information of two mixtures (coke and char) showed very close values expected.

The Determination of Glass content in fly Ash by X-Ray Diffraction (분말X선회절법에 의한 플라이 애시의 유리질 정량)

  • 이승헌;김홍주
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.159-162
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    • 2000
  • The purpose of this study is to develope an accurate procedure for measuring the glass content of fly ash produced by bituminous coal to assist in predicting their behavior in concrete. Quantitative mineralogical compositions of fly ashes were obtained by internal standard method using powder X-ray diffraction analysis. In the X-ray diffraction method, the specimen and standard fluorite were cautiously mixed and pulverized to 22$\mu$m in wet process so as to avoid the prefered orientation of the crystal and microabsorption effect of X-ray. calibration curve were fitted for several references peaks of four phases:$\alpha$-quartz. mullite, magnetite, hematite. The amount of glass was calculated by subtracting the amount of crystal phase and loss on ignition from the total amount. Glass content determined with this method ranged from 66.7 to 75.wt%.

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