• Economic and Environmental Geology
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• v.45 no.2
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• pp.79-88
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• 2012

The increased brightness and focused X-ray beams now available from laboratory X-ray sources facilitates a variety of powder diffraction experiments not practical using conventional in-house sources. Furthermore, the increased availability of 2-dimensional area detectors, along with implementation of improved software and customized sample environmental cells, makes possible new classes of in-situ and time-resolved diffraction experiments. These include phase transitions under variable pressure- and temperature conditions and ion-exchange reactions. Examples of in-situ and time-resolved studies which are presented here include: (1) time-resolved data to evaluate the kinetics and mechanism of ion exchange in mineral natrolite; (2) in-situ dehydration and thermal expansion behaviors of ion-exchanged natrolite; and (3) observations of the phases forming under controlled hydrostatic pressure conditions in ion-exchanged natrolite. Both the quantity and quality of the in-situ diffraction data are such to allow evaluation of the reaction pathway and Rietveld analysis on selected dataset. These laboratory-based in-situ studies will increase the predictability of the follow-up experiments at more specialized beamlines at the synchrotron.

• Korean Journal of Crystallography
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• v.14 no.2
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• pp.79-83
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• 2003

The microstructure of bulk electrolytic MnO₂ (EMD) was studied using x-ray diffraction and transmission electron microscopy (TEM). The bulk sample showed a typical powder x-ray diffraction pattern of EMD materials. TEM study showed that the structure of EMD is present at two length scales;grains, ∼0.2 ㎛ in diameter, and ∼10 nm crystallites within the grain. The electron beam microdiffraction study revealed that each grain is an assemblage of multiphase with a common crystallographic orientation, and_that ∼50% of the crystallites are Ramsdellite, ∼30% are ε-MnO₂, and ∼15% are Pyrolusite. The ｛1120｝peak located at about 67° in powder XRD pattern as well as a high-resolution electron microscope (HREM) image of (0001) plane support the existence of ε-MnO₂ phase.

• The Journal of the Korean dental association
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• v.23 no.3 s.190
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• pp.229-235
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• 1985

• Analytical Science and Technology
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• v.5 no.1
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• pp.111-114
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• 1992

Ordering phenomena were observed for Zn and Ta cations of $Ba(Zn_{1/3}Ta_{2/3})O_3$ under particular heat treatments, followed by a considerable lattice distortion. This lattice distortion was measured by X-ray powder diffraction with a precision of higher than 1/10,000. From this investigation, a significant lattice distortion occurred within 30 min. of sintering at $1350^{\circ}C$, and it was increased with sintering time.

• The Journal of Engineering Geology
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• v.33 no.1
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• pp.61-68
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• 2023

This study analyzed and compared the physicochemical characteristics of topsoil and subsoil of Grade 1 soil from an igneous rock area on the ecological and nature map. The water content and pH of the collected soil samples were measured, and X-ray fluorescence and X-ray diffraction analyses were performed. The results showed that the water content of the topsoil was higher than that of the subsoil, and its pH was more acidic than that of the subsoil. According to the X-ray fluorescence analysis results, sample I9 was closest to kaolinite, while sample I7 was most distant from kaolinite. All other samples were located between samples I7 and I9. The X-ray diffraction analysis showed that the average content of clay minerals was higher in the topsoil than in the subsoil. The most notable clay minerals produced included illite, vermiculite, kaolinite, chlorite, and gibbsite. The results of this study will be used as a basic data for topsoil restoration to convert subsoil into topsoil.

• Proceedings of the Korean Magnestics Society Conference
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• 1993.03a
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• pp.60-61
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• 1993

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.229.1-229.1
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• 2010

We investigated the effect of chemical acid treatments on hydrogen storage behaviors of the ordered mesoporous carbons (MCs). The surface functional groups and specific elements of the MCs were characterized with Fourier Transform Infrared (FT-IR) spectrometry and X-ray photoelectron spectroscopy (XPS). Also, the changes in the surface functional groups of the MCs were quantitatively detected by Boehm's titration method. The structural properties of the MCs were investigated using X-ray diffraction (XRD). The hydrogen adsorption capacity of the MCs was evaluated by means of adsorption isotherms at 77 K/1 bar. The formation of surface functional groups by the acidic treatments could influence on the hydrogen storage capacity of the MCs.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.2 no.2
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• pp.47-52
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• 1992

결정화 유리에서의 결정화도 측정, 혹은 소결체에서의 잔류 유리량을 측정할 때 가장 유용한 방법을 찾아내기 위하여 현재까지 보고되어 있는 방법중에서 Ohlberg와 Benedetti의 XRD를 이용한 방법과 IR을 이용한 Hirose의 방법을 선정하여 코디어라이트 조성의 유리와 β-코디어라이트의 혼합물에 대하여 결정화도를 측정하였다. 이들 측정 방법중에서 Ohlberg의 방법은 표준시료가 준비되었을 경우 약 5%의 오차를 보였으며, Benedetti의 방법은 Ohlberg의 방법보다 큰 오차를 보였지만 표준시료를 필요로 하지 않았다. Hirose의 방법은 적은 결정화도 범위에서만 적용가능한 방법인 것으로 보여졌다.

• 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 Vacuum Society Conference
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• 2013.08a
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• pp.238-238
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• 2013

사파이어 단결정은 광학 투명도, 물리적 강도, 충격 저항, 마모 부식, 높은 압력 및 온도 내구성, 생체 호환성 등 다양한 특성을 가지고 있어 다양한 분야에서 사용되고 있으며, 특히 최근에는 백색 또는 청색 LED 소자 분야에서 기판으로 주로 활용되고 있다. 이러한 사파이어 단결정 기판은 공정에서 결정 성장 조건 및 기계적 연마 등의 다양한 요인으로 결정학적 결함이 발생한다. 이러한 결정학적 결함을 제어함으로서 좋은 품질의 단결정 기판을 생산할 수 있다. 이에 따라 각종 결함 제어를 위해서 X-선, EPD, 레이저 편광법 등 다양한 방법으로 결함들을 측정하고 있다. 그 중에서도 X-선 토포그래피는 시료를 비파괴적인 방법으로 단결정의 결함 밀도와 유형 등을 파악하는데 매우 유용한 측정법이며, Lang 토포그래피로 대표되는 X-선 회절 투과법은 기판과 같은 대구경의 시료를 우수한 분해능으로 내부 결함까지 관찰할 수 있는 장점을 지니고 있다. 본 연구에서는 대구경 사파이어 단결정 기판에 내재하는 결정 결함을 확인 및 분석하기 위해 X-선 Lang 토포그래피(X-ray Lang Topography) 장비를 구축하였다. 그리고 4, 6인치 c-면 사파이어 단결정 기판의 (110), (102) 회절면의 X-선 토포그래피 측정을 통해 전위(dislocation), 스크래치(scratch), 표면데미지(surface damage), 트윈(twin), 잔류 응력(strain) 등의 결함의 유형을 식별 및 분석하였으며, 각각의 결함들의 토포그래피 이미지 형성 메커니즘에 대해 분석하였다. 이를 통해 X-선 Lang 토포그래피(X-ray Lang Topography) 장비가 대구경 사파이어 단결정 기판의 결정 결함 평가에 폭넓은 활용이 가능할 것으로 예상된다.