• Journal of the Mineralogical Society of Korea
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• v.15 no.1
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• pp.59-68
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• 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.

• 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.

• Journal of the Mineralogical Society of Korea
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• v.13 no.4
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• pp.221-230
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• 2000

이성분 희토류 원소로 치환된 4종류의 합성불화인회석(synthetic fluorapatite) (Ap49: La+Gd, Ap50:Ce+Dy, Ap51: Pr+Er, Ap54: Eu+Lu; $Ca{10-x-2y}$ $Na_{y}$ $REE_{x+y}$($P_{1-x}$ //$Si_{x}$ $_{4}$)$_{6}$ $F_{2}$, x=0.13~0.12, y=0.26~0.42)을 대상으로 X-선 회절분석을 통해 얻어진 자료를 이용하여 리트벨트 구조분석을 실시하고 치환된 희토류원소의 거동을 단결정법으로 구해진 결과와 비교.분석하였다. 리트벨트 구조분석결과 합성불화인회석은 공간군 $P6_3$/m, 단위포는 평균하여 a=9.3906(1) $\AA$, c=6.8924(1) $\AA$, V=527.36 $\AA^3$의 값을 갖는다. 구조의 정밀도를 나타내는 R 지수를 보면 $R_{B}$ / 값은 17.29~18.80이고 S(GofF)값은 1.44~1.68로 계산되었다. 불화인회석은 9개의 산소를 배위하는 Ca1자리와 6개의 산소와 하나의 불소가 배위하는 Ca2자리가 있으며 Ca1-O의 평균거리는 2.563 $\AA$이고 Ca2-O의 평균거리는 $2.460 \AA$으로 Ca1자리가 Ca2자리보다 다소 크다. 구조자리 치환식에서는 $Ca^{2+}$ / 자리를 치환하는 $REE^{3+ }$ 로 인하여 전하균형을 맞춰주기 위해서 인과규소가 함께 참여하였다. ($REE^{3}$+Si$^{ 4+}$ $2Ca^{2+}$ : Ca1) 계산된 희토류원소의 자리점유율(REE-Ca2/REE-Cal)은 원자번호가 증가함에 따라 일정하게 감소하는 경향을 보여주며 이는 희토류원소의 거동이 LREE는 크기가 상대적으로 작은 Ca2 자리에 우선 치환되고 HREE는 크기가 큰 Ca1자리에 우선 치환되는 경향을 지시한다.

• Journal of the Mineralogical Society of Korea
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• v.22 no.1
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• pp.63-72
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• 2009

Carbon-coated lithium iron phosphate ($LiFePO_4/C$) composites are synthesized by the modified mechanical activation method (modified MA process) and studied by the Rietveld structural refinement. Rietveld indices of $LiFePO_4/C$ indicate good fitting with $R_p=8.14%,\;R_{wp}=11.1%,\;R_{exp}=9.09%,\;R_B=3.88%$, and S (GofF, Goodness of fit) = 1.2, respectively. $LiFePO_4/C$ with a space group Pnma shows a = 10.3229(3)${\AA}$, b = 6.0052(2) ${\AA}$, c = 4.6939(1) ${\AA}$, and V = 290.98(1) ${\AA}^3$ in dimension, indicating good agreements with those of previous works. Synthetic powders are nano-sized ($65{\sim}90nm$) homogeneous particles with high purity. Thus the modified MA method will be an efficient process to get a high quality cathode material for commercial lithium batteries.

• Korean Institute of Interior Design Journal
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• no.40
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• pp.68-75
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• 2003

The purpose of this study is to find out the expression style of space in Rietveld's early works in comparison with Mondrian's paintings. Through investigating the development of their works and analyzing the composition and disposition type of elements such as point, line, plane, color in the selected works, we can draw the following conclusions. .First, Rietveld pursues the dissolution of traditional volume and the de-composition of elements as Mondrian does. Second, the painterly property of plane is emphasized by the projection of separately floating elements on the picture plane. Third, the separating the layer of lines from the layer of planes and the re-combination of these two layers present the superimpositional image of three-dimensional objects. This leads into new conception of architectural space and develops the transparency and the extension of plan in modem architecture.

• 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.

• Journal of The Korean Digital Architecture Interior Association
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• v.3 no.1
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• pp.9-14
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• 2003

The purpose of this study is to find out organizing strategy of de-composition works in modern plastic arts. Through investigating the development process of De Stijl painters and Rietveld's early works and analyzing the composition and disposition type of elements such as point, line, plane, color in the selected works, we can draw some conclusions. First, Rietveld pursues the dissolution of traditional volume and the de-composition of elements as Mondrian does through crossing-connection of three listels with quadrangular section. Second, Rietveld reorganized de-composition elements with detached lines and color planes. Third, Rietveld experimented possibility of new plastic space through displacing elements, opening space, making anti-gravity space.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.74-75
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• 2021

This study attempted to study the setting time and compressive strength according to the sugar type through XRD. Setting time was found to be delayed the most when mixing white sugar, and setting time was promoted when mixing Saccharin and Aspartame. It was found that when white sugar and Grosvener siraitia were mixed, the compressive strength was higher than that of Control. Aspartame the age passed, C₃S decreased and Ca(OH)₂ increased.

• Proceedings of the KSEEG Conference
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• 2001.04a
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• pp.372-375
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• 2001

• 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.