• 분석과학
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• 제26권5호
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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.

• 한국세라믹학회지
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• 제48권5호
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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.

• 분석과학
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• 제25권1호
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• pp.33-38
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• 2012

염화물 고정화능력의 중요성에도 불구하고 고정화능력을 측정하는 것은 어려우며 특히, 이미 건설되어 공용중인 구조물에서는 더욱 어렵다. 실제로 고정염화물을 측정하는 과정은 온도, 시료의 분말도, 공극수 추출기법 등과 같은 환경적 요인에 의해 큰 영향을 받는다. 본 연구에서는 X-선 회절분석법(XRD; X-ray diffraction)을 이용하여 콘크리트 내 염화물 이온의 고정화능력을 정량화하는 방법에 대해 중점을 두고 연구를 진행하였다. 염화물의 고정능력 isotherm은 물/시멘트비, 양생기간, 결합재 종류에 영향을 받으며 Langmuir isotherm 을 통하여 일단 결정된 고정염화물(Friedel 염)은 XRD를 이용하여 동시에 분석을 진행한다. XRD 그래프에서 나타난 고정염화물량의 피크 강도와 측정된 고정염화물의 총량의 관계를 결정한다. 결과적으로 양생기간이 증가될수록, 물/시멘트비가 감소될수록 고정화 능력은 증가하였다.

• 분석과학
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• 제19권5호
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• pp.407-414
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• 2006

An X-ray diffractometer for spatially resolved X-ray diffraction measurements was developed to identify phase in the narrow (micron-scaled) region of high burn-up fuels and some nuclear materials. The micro-XRD was composed of an X-ray microbeam alignment system and a sample micro translation system instead of a normal slit and a fixed sample stage in a commercial XRD. The X-ray microbeam alignment system was fabricated with a microbeam concentrator having two Ni deposited mirrors, a vertical positioner, and a tilt table for the generation of a concentrated microbeam. The sample micro translation system was made with a sample holder and a horizontal translator, allowing movement of a specimen at $5{\mu}m$ steps. The angular intensity profile of the microbeam generated through a concentrator was symmetric and not distorted. The size of the microbeam was $4,000{\times}20{\mu}m$ and the spatial resolution of the beam was $47{\mu}m$ at the sample position. When the diffraction peaks were measured for a $UO_2$ pellet specimen by this system, the reproducibility ($2{\Theta}={\pm}0.01^{\circ}$) of the peaks was as good as a conventional X-ray diffractometer. For the cross section of oxidized titanium metal, not only $TiO_2$ in an outer layer but also TiO near an oxide-metal interface was observed.

• 한국세라믹학회지
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• 제40권5호
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• pp.481-487
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• 2003

고로 연소대의 거동에서 석탄, 미연소탄, 코크스의 함량을 측정할 수 있는 분석기술이 필요하다 탄소질 재료에 분말 X-선 회절 정량법을 적용하여 석탄, 미연소탄, 코크스의 혼합시료에 대하여 탄소의 함량을 정량적으로 파악할 수 있는 방법을 연구하였다. 분석을 위하여 석탄을 1000~140$0^{\circ}C$의 온도에서 시간을 달리하여 미연소탄을 제조하여 XRD를 이용하여 분석하였다. 또한, XRD 분석을 위해 제조된 시료에 대하여 HCI과 HF용액을 이용하여 시료 내에 포함된 광물성분을 제거하였다. XRD측정 결과로부터 결정 층의 두께(L $c_{(002)}$)와 결정 층의 크기(L $a_{(10)}$), 방향족분율, 흑연화도, 면간거리( $d_{0.2}$), 탄소 층의 수( $N_{ι}$)를 측정하였다. 그 결과로 열처리 온도가 증가됨에 따라 L $c_{(002)}$, L $a_{(10)}$, 흑연화도는 증가하였으며, 면간거리와 반가폭은 감소하였다. 따라서 미연소탄-코크스 혼합물에 대한 결정층의 두께자료는 합성시료로부터 미연소탄의 함량을 정량화할 수 있었다.

• 한국전기전자재료학회논문지
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• 제35권5호
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• pp.431-438
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• 2022

기능성 소재연구에서 in situ 분석 기법은 외부 자극 (전기장, 자기장, 빛, 등) 또는 주변 환경 (온도, 습도, 압력, 등)과 같이 주어진 자극에 의해 소재의 물리적 특성이 어떻게 활성화/진화되는지 분석하는데 있어서 매우 중요하다. 특히, 전기장 인가에 따른 in situ X-선 회절(XRD) 실험은 다양한 강유전체, 압전체, 전왜 재료의 외부 전기장 인가에 따른 전기-기계적 반응의 기본 원리를 이해하기 위해 광범위하게 활용되었다. 본 튜토리얼 논문에서는 일반 실험실 규모의 XRD 장비를 이용하여 전기장 인가에 따른 in situ XRD 분석의 기본 원리/핵심 개념을 간략하게 소개한다. In situ XRD 측정법은 외부 전기장을 인가하여 구동되는 다양한 전기-기계 재료의 구조적 변형을 체계적으로 식별/모니터링하는 데 매우 유용할 것으로 기대한다.

• 치위생과학회지
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• 제22권3호
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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.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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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.

• 한국세라믹학회지
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• 제35권10호
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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.

• 분석과학
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• 제20권6호
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• pp.502-507
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• 2007

X 선 회절법은 물질 내부에 원자의 배열 상태를 연구하는데 널리 사용되는 실험 방법으로써 넓은 응용 범위를 가지고 있다. 특히 분말 X 선 회절법은 비파괴적으로 다양한 형태의 시료에 대한 측정이 가능하기 때문에 결정의 배향성, 결정의 크기, 결정 내부의 응력 측정 등에 널리 이용되고 있다. 분말 X 선 회절 방법을 이용하여 혼합물의 성분을 정량적으로 측정하기 위해서는 시료를 구성하고 있는 source 스펙트럼을 도출하고 혼합된 시료의 XRD 스펙트럼에 회귀식을 적합시켜 혼합물 구성비를 얻는 방법이 제안된 바 있다. 그러나 구성성분의 특성상 스펙트럼의 피이크가 폭이 좁고 민감한 경우에는 노이즈의 영향을 받아 도출된 source 스펙트럼이 원래의 순수성분의 형태와 달리 나타날 수 있다. 특히 순수성분 시료를 구할 수 없거나 측정이 불가능한 경우 혼합물 구성비 측정에 어려움이 있다. 본 연구에서는 노이즈 간섭에 의한 source 스펙트럼 도출의 문제를 해결하는 방안으로 비음독립성분분석을 이용하여 혼합된 미지시료로부터 순수한 성분에 해당하는 스펙트럼을 분리해내는 방법을 제안하고자 한다.