• Title/Summary/Keyword: Rietveld Method

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A Study on the Reappraisal of Gerrit Thomas Rietveld's Design Concept (게리트 리트벨트 디자인 개념 재평가에 관한 연구)

  • Lee, Kwang-In
    • Journal of The Korean Digital Architecture Interior Association
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    • v.12 no.4
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    • pp.97-105
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    • 2012
  • This study aims to evaluate Rietveld's creative design style and concepts. To this end, I looked into the evaluation of major researchers on Rietveld, classified all his works into four groups according to the design types and analyzed them. As follows: based on the results of the analysis of works I concluded. First, Rietveld created the concept of the spatial extension to the ingenious joint which had the structural node formed of three listels with quadrangular section. It is the design innovation that led to liberate the closed construction. Second, Rietveld had opened up the possibility to neutralize the gravitational three-dimensional works. He subtracted the weight in the direction of gravity from the three-dimensional structure of the works and painted the three primary colors on them partially to get rid of the original material color. Therefore they looked like the forms liberated from gravity. Third, Rietveld ripped off the surfaces of cube through several formative experiments and decomposed the volume into the tesseract. Through this method of realizing the new plastic concepts, he completed the architectural models of weightlessness. Fourth, Rietveld opened the possibility of the realization of the three-dimensional works integrated all space and time in the one-pieced works and the folded works. Fifth, Rietveld steadily experimented and realized the internal and external integration of time and space in his later works.

Application of Inverse Pole Figure to Rietveld Refinement: II. Rietveld Refinement of Tungsten Liner using Neutron Diffraction Data

  • Kim, Yong-Il;Lee, Jeong-Soo;Jung, Maeng-Joon;Kim, Kwang-Ho
    • The Korean Journal of Ceramics
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    • v.6 no.3
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    • pp.240-244
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    • 2000
  • The three-dimensional orientation distribution function of a conical shaped tungsten liner prepared by the thermo-mechanical forming process was analyzed by 1.525$\AA$ neutrons to carry out the Rietveld refinement. The pole figure data of three reflections, (110)(220) and (211) were measured. The orientation distribution functions for the normal and radial directions were calculated by the WIMV method. The inverse pole figures of the normal and radial directions were obtained from their orientation distribution functions. The Rietveld refinement was performed with the RIETAN program that was slightly modified for the description of preferred orientation effect. We could successfully do the Rietveld refinement of the strongly textured tungsten liner by applying the pole density of each reflection obtained from the inverse pole figure to the calculated diffraction pattern. The correction method of preferred orientation effect based on the inverse pole figures showed a good improvement over the semi-empirical texture correction based on the direct usage of simple empirical functions.

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Quantitative Analysis of Feldspar Mixture Samples Using the Rietveld Refinement Method (Rietveld Refinement 방법을 응용한 장석 혼합시료의 정량분석 연구)

  • Shim, Sang-Heon;Ahn, Jung-Ho;Kim, Soo-Jin
    • Journal of the Mineralogical Society of Korea
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    • v.7 no.1
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    • pp.62-79
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    • 1994
  • The quanttative and structural analysis of the binary standard mixtures of albite and quartz, and microcline and albite were carried out using the Rietveld refinement method in order to investigate the accuracy and precision of the method. The quantitative analysis using the Rietveld method results in a standard deviation of 4 wt % for the albite-quartz standard mixtures and 1 wt % for the microcline-albite standard mixtures, suggesting that its accuracy is far better than that of the conventional XRD method in which only a few selected peaks are utilized. Furthermore, the unit-cell parameters of component minerals in mixtures were also estimated accurately during the analysis. It was observed that the refined weight fractions deviate systematically from their measured values when the method is applied to the mixtures that contain minerals with different degrees of preferred orientation, such as albite-quartz mixtures. The preferred orientation parameters and R-values suggest that the systematic deviation is caused as a result of the preferred orientation effect of feldspar crystallites. It is evident that the preferred orientation corrections are of help for the accurate determination of unit-cell parameters, although they may not improve the result of quantitative analysis significantly. The refined weight fraction of the mineral with higher degree of preferred orientation in mixture is greater than the measured one. This is apparently caused by the effect of geometry of feldspar crystallites in the surface of the mounted sample. The Rietveld refinement method minimizes the problems inherent in the traditional XRD methods, such as the line overlap, primary extinction, and preferred orientation effect, by fitting every data point in a whole pattern explicitly. Furthermore, accurate unit-cell parameters as well as scale factors that can be obtained from the Rietveld refinement are used for the quqantification. The present stdudy demonstrates that the Rietveld method yields far more accurate analytical result than the conventional XRD quantitative analysis method does.

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Comparison of Olivine Crystal structures by Single Crystal and Rietveld Refinement Methods (단결정법과 리트벨트 구조해석법에 의한 감람석 결정 구조의 비교 연구)

  • 최진범;김영호;이지은
    • Journal of the Mineralogical Society of Korea
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    • v.10 no.1
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    • pp.50-59
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    • 1997
  • the crystal structure of pale green gem-quality olivine from Bisbee mine,Arizona, (Mg1.83Fe0.18)Si0.99O4, a=4.7608(4)$\AA$, c=5.9903(6)$\AA$, c=5.9903(4)$\AA$, V=291.49(1)$\AA$, Pbnm, Z=4 has been refined by both single-crystal and Rietveld methods to R(%) indices of 2.20 and 9.07, respectively. Comparison of site occupancies, cell dimensions, atomic coordinations, and interatomic distances/angles obtained from both methods shows that the Rietveld method produces more accurate site scattering values, cell dimension, and atomic positions than the single-crystal method. This indicates that the Rietveld method is a useful technique for the structural characterization and crystal-chemical study of powdered samples of natural minerals and synthetic materials.

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A Study of Practical and Optimized Mineral Quantification (실용적이고 최적화된 광물정량분석법 연구)

  • Son, Byeong-Kook;An, Gi-O
    • Korean Journal of Mineralogy and Petrology
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    • v.34 no.4
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    • pp.227-239
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    • 2021
  • A practical and effective method of X-ray powder diffraction analysis was investigated for quantitative analysis of the mineral content of natural samples. Sample mounting experiments were conducted to select the best randomly oriented powder sample mount. A comparative experiment was also made between a reference intensity ratio (RIR) method, which compares a single peak intensity with standard material, and the Rietveld method, which calculates a full X-ray diffraction pattern, to search for the effective method of mineral quantification. In addition, samples containing amorphous minerals were quantitatively analyzed by the Rietveld method and the efficiency was reviewed. As a result of the study, the optimal random orientation could be reached by the side mounting method. The Rietveld method using the full pattern of X-ray diffraction was more suitable for mineral quantitative analysis, rather than the RIR method using a specific peak. However, either method could depend on the analyst's experience in addition to analytical technique. Moreover, amorphous minerals can be quantitatively analyzed by the Rietveld method, and the analysis results make the geological analysis possible.

The structure analysis of $Y_1Ba_2Cu_3O_x$ high Tc superconductor based on rietveld method (리트벨트 해석법을 이용한 $Y_1Ba_2Cu_3O_x$ 고온 초전도체의 구조분석)

  • 채기병;소대화
    • Electrical & Electronic Materials
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    • v.8 no.6
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    • pp.780-786
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    • 1995
  • For the execution of RIETAN program adopting Rietveld Analysis Method, the sample superconductor is made according to the solid state synthesis method at 920.deg. C for 24hrs, and was examined for the optimization of parameters needed to analyze Rietveld method with the input of the measured pattern data after measuring the pattern resulted from the X-ray diffraction. It was proven that the lattice constant of the superconductor which was consisted of Pmmm orthorhombic crystal structure in the analyzed space group correspond to the presented theoretical lattice constant a=3.8887(8).angs., b=3.8238(4).angs., c=11.7079.angs.. Therefore, it was examined and confin-ned that the R factor, which was compensated after analyzing the structure of superconductor resulted from this experimented data with the computer simulation, was refined to $R_{wp}$=8.83[%], $R_{P}$=6.47[%], $R_{I}$=10.08[%], $R_{F}$=7.19[%], $R_{E}$=3.76[%]. On the basis of these experimental data, the significant parameter such as the scale factor(S) and the zero point shift(Z) and FWHM value(U,V,W) were optimized as follows; S=2.0827E-3, Z=0.2146, U=4.2761E-2, V=1.7983E-2, and W=2.6768E-2.2.2.2.2.2.

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Characterization of crystal phase evolution in cordierite honeycomb for diesel particulate filter by using rietveld refinement and SEM-EDS methods (Rietveld 정밀화법과 SEM-EDS 분석에 의한 DPF용 코디어라이트 하니컴 세라믹스의 결정성장 과정 분석)

  • Chae, Ki-Woong;Kim, Kang San;Kim, Jeong Seog;Kim, Shin-Han
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.31 no.3
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    • pp.116-126
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    • 2021
  • Diesel particulate filter (DPF) is a typical application field of cordierite (Mg2Al4Si5O18) honeycomb. Green body for DPF honeycomb was extruded using slurry paste and sintered at the temperature range of 980~1450℃. Quantitative crystal phase analysis was carried out by using Rietveld refinement method for powder XRD data. In conjunction with the quantitative Rietveld analysis, SEM-EDS analysis was carried for the crystal phases (indialite, cordierite, cristobalite, alumina, spinel, mullite, pro-enstatite). After removing amorphous phase on the sintered surfaces by chemical etching method, the shape and composition of the crystal phases can be clearly identified by SEM-EDS method. By combining the Rietveld refinement method and SEM-EDS analysis, crystal phase evolution process in DPF cordierite ceramics could be clarified. In addition, the coefficient of thermal expansion (CTE) of the DPF honeycombs were measured and compared with the calculated CTEs based on the quantitative crystal phase analysis results.

Phase Transition adn Crystal Structure Analysis Using Rietveld Method in the $(Na_{0.3}Sr_{0.7})(Ti_{0.7}M_{0.3})O_3 (M=Ta, Nb)$ System (Rietveld 법을 이용한 $(Na_{0.3}Sr_{0.7})(Ti_{0.7}M_{0.3})O_3 (M=Ta, Nb)$ 계에서의 결정구조 해석과 상전이 특성)

  • 정훈택;김호기
    • Journal of the Korean Ceramic Society
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    • v.32 no.5
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    • pp.582-586
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    • 1995
  • The crystal structures of (Na0.3Sr0.7)(Ti0.7M0.3)O3 (M=Ta, Nb) compounds were determined using the Rietveld method. Due to the tilting of a oxygen octahedron, (Na0.3Sr0.7)(Ti0.7Nb0.3)O3 had a superlattice of doubled a, b and c of simple perovskite. The crystal structure of (Na0.3Sr0.7)(Ti0.7M0.3)O3 was tetragonal with a space group 14/mmm. The crystal structure of (Na0.3Sr0.7)(Ti0.7M0.3)O3 was a cubic with space group Pm3m, in which no tilting of oxygen octahedron was observed. The difference in the oxygen tilting of these two materials was due to the larger covalency of Nb-O bond than that of Ta-O bond, which induced a strong $\pi$Nb0 bonding in (Na0.3Sr0.7)(Ti0.7M0.3)O3. Therefore, the higher transition temperature of (Na0.3Sr0.7)(Ti0.7M0.3)O3 could be related to the larger tilting of oxygen octahedron.

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A Study of Mineral Quantification on Clay-Rich Rocks (점토질 암석의 광물정량 분석법 연구)

  • Byeong-Kook, Son;Gi-O, An
    • Korean Journal of Mineralogy and Petrology
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    • v.35 no.4
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    • pp.431-445
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    • 2022
  • A quantitative phase analysis method of X-ray powder diffraction was studied to determine the mineral content of clay-rich rocks practically as well as effectively. For quantitative X-ray powder diffraction analysis of the clay-rich rocks, it is necessary to prepare whole-rock powder samples with a random orientation by side mounting method. In addition, for the identification of the clay minerals in the rock, it is required to prepare an oriented mount specimen with a clay particle size of 2 ㎛ or less, ethylene glycol treatment, and heat treatment. RIR (reference intensity ratio) and Rietveld method were used for the quantitative analysis of the clay-rich rocks. It was possible to obtain the total clay and the non-clay minerals contents from the whole-rock X-ray diffraction profiles using the RIR values. In addition, it was possible to calculate the relative content of each clay mineral from the oriented X-ray diffraction profiles of the clay particle size and assign it to the total clay. In the Rietveld method of whole-rock X-ray diffraction, effective quantitative values were obtained from the Rietveld diffraction patterns excluded the region of less than 10 degrees (2θ). Similar quantitative values were shown in not only the RIR but the Rietveld methods. Therefore, the analysis results indicate a possibility of a routine quantitative analysis of clay-rich rocks in the laboratory. However, quantitative analysis of clay minerals is still a challenge because there are numerous varieties of clay minerals with different chemical and structural characteristics.