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

Search Result 147, Processing Time 0.056 seconds

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
    • /
    • v.35 no.10
    • /
    • pp.1113-1119
    • /
    • 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.

  • PDF

Crystal and Block Structures of Hexagonal Ferrites (육방정 페라이트의 결정과 Block 구조)

  • Shin, Hyung-Sup
    • Journal of the Korean Ceramic Society
    • /
    • v.49 no.3
    • /
    • pp.205-215
    • /
    • 2012
  • It has been studied the crystal and block structures of the hexagonal ferrites with M, W, Y and Z types prepared by various coprecipitation-oxidation method. The structures have been refined with a Rietveld analysis of the powder X-ray diffraction pattern with high precision ($R_{WP}$ <0.09, $R_I$ <0.03). The density difference between the S-blocks was proportioned to the cobalt contents in hexagonal ferrites, but that between the R or T-blocks was relatively small. Compared with the blocks and cation-oxygen polyhedra in BaM ($BaFe_{12}O_{19}$), those were bulky to the normal direction for the c-axis in $Co_2W$ ($BaCo_2Fe_{16}O_{27}$) and to the parallel direction for the c-axis in $Co_2Y$ ($Ba_2Co_2Fe_{12}O_{22}$) and $Co_2Z$ ($Ba_3Co_2Fe_{24}O_{41}$). The S-blocks of $Co_2W$, $Co_2Y$, and $Co_2Z$ were unstable and distorted. Because the T-block of $Co_2Z$ was unstable, the T-block was decomposed into the Ba-rich phase and $Co_2W$ at high temperatures above $1200^{\circ}C$. A standard powder X-ray diffraction pattern for $Co_2Z$ was proposed as well.

Application Study of Chemoinfometrical Near-Infrared Spectroscopic Method to Evaluate for Polymorphic Content of Pharmaceutical Powders (일본의 근적외선분광법에 대한 제약회사 응용 및 현황)

  • Otsuka, Makoto
    • Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
    • /
    • 2002.11a
    • /
    • pp.97-117
    • /
    • 2002
  • A chemoinfometrical method for quantitative determination of crystal content of indomethacin (IMC) polymorphs based on fourie-transformed near-infrared (FT-NIR) spectroscopy was established. A direct comparison of the data with the ones collected from using the conventional powder X-ray diffraction method was performed. Pure $\alpha$ and ${\gamma}$ forms of IMC were prepared using published methods. Powder X-ray diffraction profiles and NIR spectra were recorded for six kinds of standard materials with various content of ${\gamma}$ form IMC. The principal component regression (PCR) analyses were performed based on normalized NIR spectra sets of standard samples of known content of IMC ${\gamma}$ form. A calibration equation was determined to minimize the root mean square error of the prediction. The predicted ${\gamma}$ form content values were reproducible and had a relatively small standard deviation. The values of ${\gamma}$ form content predicted by two methods were in close agreement. The results were indicated that NIR spectroscopy provides for an accurate quantitative analysis of crystallinity in polymorphs compared with the results obtained by conventional powder X-ray diffractometry.

  • PDF

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
    • /
    • v.34 no.8
    • /
    • pp.2375-2380
    • /
    • 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.

Measurement of Crystallite Size of Method and Evaluation of Crystal Defects (X선 회절법에 의한 할로겐화 은 유제입자의 크리스탈라이트 크기 측정과 결정결함 평가에 관한 연구)

  • Bae, Chang-Hwan;Lee, Ju-Hee;Han, Chang-Suk
    • Korean Journal of Materials Research
    • /
    • v.19 no.6
    • /
    • pp.330-336
    • /
    • 2009
  • The size of crystallites in mono-dispersed cubic silver bromide grains was measured by applying a powder X-ray diffraction method and Scherrer's equation to grains that were suspended in swollen gelatin layers. In order to evaluate the existence of defects, the measured crystallite size was compared to those measured by using a scanning electron microscope. In the case of the grains prepared by the controlled double jet method, the size of crystallites was equal to the edge length of the grains that had edge lengths smaller than 400 nm. This result proved the usefulness of the above-stated method for measuring the size of crystallites and also evaluating the presence of any crystal defect in each grain. In the case of the grains, which were precipitated in the presence of a sensitizing dye and potassium iodide, the size of crystallites was smaller than the edge's length, indicating the discontinuities in the grains introduced during the precipitation process.

Hydrothermal Synthesis of Mesostructured Vanadium Oxide and Application of UV-Ozone Treatment

  • Chang, Ju-Yeon;Jung, Duk-Young
    • Bulletin of the Korean Chemical Society
    • /
    • v.24 no.5
    • /
    • pp.613-616
    • /
    • 2003
  • Effect on hydrothermal treatment of lamellar vanadium oxides was investigated and the formation of hexagonal and cubic mesophase was found. This lamellar materials were prepared by mixing of cetyltrimethylammonium-bromide and pH-controlled sodium metavanadate solution. Thermal method and UV/O₃treatment were applied to extract organic template. The structure of resulting product was studied by powder X-ray diffraction and transmission electron microscopy (TEM).

Preparation of Spherical Nickel Powder by Hydrothemal Process (수열합성법을 이용한 구형 니켈분말 제조)

  • 원창환;배장호;이종현;김병범
    • Journal of Powder Materials
    • /
    • v.11 no.3
    • /
    • pp.217-223
    • /
    • 2004
  • Submicron nickel powders were prepared from aqueous solution under hydrothermal condition. The experimental conditions including the types of protective agents, concentration of the solution and the pH were studied in detail. Starting concentration of nickel ion is a dominant factor affecting particle size. It was shown that the subsequent addition of Poly Vinyl Pyrrolidone(PVP) and Sodium Dodecyle Sulfate(SDS) can help to disperse the nickel powder. X-ray diffraction and SEM were employed to characterize the products.

Synthesis and Characterization of Intergrowth Type Perovskite Oxide NdSr2MnCrO7

  • Singh, Devinder
    • Bulletin of the Korean Chemical Society
    • /
    • v.32 no.8
    • /
    • pp.2761-2764
    • /
    • 2011
  • A new Ruddlesden-Popper phase $NdSr_2MnCrO_7$ has been prepared by the standard ceramic method. The powder X-ray diffraction studies suggest that the phase crystallizes with tetragonal unit cell in the space group I4/mmm. The electrical transport properties show that the phase is an electrical insulator and the electrical conduction in the phase occurs by a 3D variable range hopping mechanism. The magnetic studies suggest that the ferromagnetic interactions are dominant.

Intercalation of Functional Organic Molecules with Pharmaceutical, Cosmeceutical and Nutraceutical Functions into Layered Double Hydroxides and Zinc Basic Salts

  • Hwang, Seong Ho;Han, Yang Su;Choe, Jin Ho
    • Bulletin of the Korean Chemical Society
    • /
    • v.22 no.9
    • /
    • pp.1019-1022
    • /
    • 2001
  • Negatively charged functional organic molecules such as retinoic acid, ascorbic acid, indole acetic acid, citric acid, salicylic acid, acidic dye (indigo carmine, Food Blue 1) are intercalatively encapsulated by zinc basic salt (hydrozincite) and layered double hydroxide. Such functional organic-inorganic nanohybrids are realized via coprecipitation reaction involving simultaneous formation of layered inorganic lattice and intercalation of anionic species. The heterostructural nature of these nanohybrids, their particle morphology and textural characterizations are mainly discussed on the basis of Powder X-ray Diffraction and Field Emission Scanning Electron Microscopy results.

Chemistry and Rietveld Structure Refinement of Nb-rich Perovskite, $Ca_2NbFe^{3+}O_6$ (네오비움 페롭스카이트($Ca_2NbFe^{3+}O_6$)의 화학조성 및 리트벨트 구조분석 연구)

  • ;Frank C. Hawthorne
    • Journal of the Mineralogical Society of Korea
    • /
    • v.15 no.1
    • /
    • pp.59-68
    • /
    • 2002
  • Chemical analyses and Rietveld structural refinement with powder X-ray diffraction data were done for Nb-rich perovskite, named latrappite ($Ca_2NbFe^{3+}O_6$)from the Oka, Quebec, Canada. Latrappite is shown to be a member of a continuous solid solution of $CaTiO_3-NaNbO_3-Ca_2NbFe^{3+}O_6$ and approximately $(Ca_{1.5}Na_{0.4})\;(Nb_{0.1}Ti_{0.6}Fe_{0.4})O_6$ in composition. The crystal structure of latrappite, determined by Rietveld refinement, is similar to that of perovskite ($CaTiO_3$). It differs in that replacement of Ti by Nb and $Fe^{3+}$ results in greater distortion and tilting of the $TiO_6$ framework octahedra relative to $CaTiO_3$. Revised unit-cell parameters of latrappite are a=5.4474(4), b=5.5264(4), c=7.7519(5) ${\AA},\;V=233.4(3){\AA}^3$ space group Pbnm.