• Analytical Science and Technology
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• v.26 no.5
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• pp.340-351
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• 2013

The chemical element and structural characterization of different types of cements and its brick stones are been investigated under forensic aspects using X-ray florescence (XRF) and X-ray diffraction (XRD) spectrometer. The XRF provides rapid compositional data for controlling almost all stages of raw materials, clinker and cement. The decisive advantage of XRD methods is based on the unique character of the diffraction patterns of crystalline substances, the ability to distinguish between elements and their oxides, and the possibility to identify chemical compounds, polymeric forms, and mixed crystals by non-destructive examination. Therefore, combination of these examinations is useful and able to apply for the forensic analysis in comparison of cements and brick stones. There are more study remained to determine the viability of method for forensic analysis of brick stones and the limits of the discrimination that can be achieved.

• Journal of the Korean Ceramic Society
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• v.48 no.5
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• pp.458-462
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• 2011

The strength of ceramic was improved by lamination by suppressing the propagation of cracks with compressive residual stress in the face layer of the laminate. Hot pressed SiAlON+SiC/SiC/SiAlON+SiC laminate discs were fabricated for tailored residual stress. The residual stress in this laminate was studied by X-ray diffraction (XRD). There was considerable compressive residual stress in the face layer. A Finite Element Analysis (FEA) was performed to support the measured XRD results and to determine the stress field in the laminate. The residual stress measured by XRD had satisfactory agreement with the analytically calculated and FEA values. The measured value by XRD was -385 ${\pm}$ 20 MPa over most of the face layer. The calculated and FEA values were -386 MPa and -371MPa, respectively. FEA also showed significantly modified stresses and the maximum tensile stress near the edge region which are possible crack generators in the presence of flaws or contact damage.

• 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.

• 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.

• Archives of Metallurgy and Materials
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• v.63 no.3
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• pp.1439-1442
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• 2018

A nanocrystalline Ti alloy powder was fabricated using cryomilling. The grain size and lattice strain evolution during cryomilling were quantitatively analyzed using X-ray diffraction (XRD) based on the Scherrer equation, Williamson-Hall (W-H) plotting method, and size-strain (S-S) method assuming uniform deformation. Other physical parameters including stress and strain have been calculated. The average crystallite size and the lattice strain evaluated from XRD analysis are in good agreement with the result of transmission electron microscopy (TEM).

• Journal of dental hygiene science
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• v.22 no.3
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• pp.191-198
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• 2022

Background: The purpose of this study was to evaluate the composition of the crystal phases of various calcium silicate-based materials (CSMs): ProRoot white MTA^Ⓡ (mineral trioxide aggregate) (WMTA), Ortho MTA^Ⓡ (OM), Endocem MTA^Ⓡ (EM), Retro MTA^Ⓡ (RM), Endocem Zr^Ⓡ (EN-Z), Biodentine^TM (BD), EZ-seal^TM (EZ), and OrthoMTA III (OM3). Methods: In a sample holder, 5 g of the powder sample was placed and the top surface of the material was packed flat using a sterilized glass slide. The prepared slides were mounted on an X-ray diffraction (XRD) instrument (D8 Advance; Bruker AXS GmbH, Germany). The X-ray beam 2θ angle range was set at 10~90° and scanned at 1.2° per minute. The Cu X-ray source set to operate at 40 kV and 40 mA in the continuous mode. The peaks in the diffraction pattern of each sample were analyzed using the software Diffrac (version 2.1). Then, the peaks were compared and matched with those of standard materials in the corresponding Powder Diffraction File (PDF-2, JCPDS International Center for Diffraction Data). A powder samples of the materials were analyzed using XRD and the peaks in diffraction pattern were compared to the Powder Diffraction File data. Results: Eight CSMs showed a similar diffraction pattern because their main component was calcium silicate. Eight CSMs showed similar diffraction peaks because calcium silicate was their main component. Two components were observed to have been added as radiopacifiers: bismuth oxide was detected in WMTA, OM, and EM while zirconium oxide was detected in RM, EN-Z, BD, EZ, and OM3. Unusual patterns were detected for the new material, OM3, which had strong peaks at low angles. Conclusion: It was caused by the presence of Brushite, which is believed to have resulted in crystal growth in a particular direction for a specific purpose.

• Analytical Science and Technology
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• v.20 no.6
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• pp.502-507
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• 2007

X-ray diffraction method has been widely used for qualitative and quantitative analysis of a mixture of materials since every crystalline material gives a unique X-ray diffraction pattern independently of others, with the intensity of each pattern proportional to that material's concentration in a mixture. For determination of mixing ratios, extracting source spectra correctly is important and crucial. Based on the source spectra extracted, a regression model with non-negativity constraint is applied for determining mixing ratios. In some mixtures, however, X-ray diffraction spectrum has sharp and narrow peaks, which may result in partial negative source spectrum from independent component analysis. We propose several procedures of extracting non-negative source spectra and determining mixing ratios. The proposed method is validated with experimental data on powder mixtures.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.5
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• pp.431-438
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• 2022

In functional materials, in situ experimental techniques as a function of external stimulus (e.g., electric field, magnetic field, light, etc.) or changes in ambient environments (e.g., temperature, humidity, pressure, etc.) are highly essential for analyzing how the physical properties of target materials are activated/evolved by the given stimulation. In particular, in situ electric-field-dependent X-ray diffraction (XRD) measurements have been extensively utilized for understanding the underlying mechanisms of the emerging electromechanical responses to external electric field in various ferroelectric, piezoelectric, and electrostrictive materials. This tutorial article briefly introduces basic principles/key concepts of in situ electric-field-dependent XRD analysis using a lab-scale XRD machine. We anticipate that the in situ XRD method provides a practical tool to systematically identify/monitor a structural modification of various electromechanical materials driven by applying an external electric field.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.113-114
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• 2017

In this study, the change of composition of cement hardened at high temperature through XRD was observed. The specimen was made of cement paste and the heating rate condition was applied at rapid thermal annealing (10.0℃ / min). The decrease of calcium hydroxide was not confirmed, but the calcium carbonate tended to be impossible or decreased after 800℃. Calcium silicate and larnite were observed to increase with increasing temperature. It is considered that silicic acid, which is a stable structure due to the decomposition of calcium silicate, is changed into a phase such as lime.

• Carbon letters
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• v.26
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• pp.11-17
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• 2018

Milled carbon fiber (mCF) was prepared by a ball milling process, and X-ray diffraction (XRD) diffractograms were obtained by a $2{\theta}$ continuous scanning analysis to study mCF crystallinity as a function of milling time. The raw material for the mCF was polyacrylonitrile-based carbon fiber (T700). As the milling time increased, the mean particle size of the mCF consistently decreased, reaching $1.826{\mu}m$ at a milling time of 18 h. The XRD analysis showed that, as the milling time increased, the fraction of the crystalline carbon decreased, while the fraction of the amorphous carbon increased. The (002) peak became asymmetric before and after milling as the left side of the peak showed an increasingly gentle slope. For analysis, the asymmetric (002) peak was deconvoluted into two peaks, less-developed crystalline carbon (LDCC) and more-developed crystalline carbon. In both peaks, Lc decreased and $d_{002}$ increased, but no significant change was observed after 6 h of milling time. In addition, the fraction of LDCC increased. As the milling continued, the mCF became more amorphous, possibly due to damage to the crystal lattices by the milling.