• Journal of the Mineralogical Society of Korea
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• v.20 no.4
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• pp.351-356
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• 2007

The crystal structure of $Li(ND_4)SO_4$ was analyzed by X-ray and neutron diffraction methods. The crystal is a deuterated $Li(NH_4)SO_4$ and one of the ferroelectric materials with hydrogen atoms. The crystal is orthorhombic at room temperature, $P2_1nb$, with lattice parameters of $a=5.2773(5)\;{\AA},\;b=9.1244(23)\;{\AA},\;c=8.7719(11)\;{\AA}$ and Z=4. Neutron intensity data were collected on the Four-Circle diffractometer (FCD) at HANARO in Korea Atomic Energy Research Institute and X-ray date were given by Prof. Y. Noda of Tohoku University Japan. The structure was refined by full-matrix least-square to final R value of 0.070 for 1450 observed reflections by X-ray diffraction and to final R=0.049 for 745 observed reflections by neutron diffraction. With X-ray data we obtained only one hydrogen atomic position. However, not only all atomic positions of four hydrogen atoms at $NH_4$ but also the occupation factors of D and H were refined with neutron data. From this results we obtained the average chemical structure of this sample, $LiND_{3.05}H_{0.95}SO_4$.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1996.11a
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• pp.179-189
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• 1996

X-선 회절법에 의하여 Graphite 화이버-알루미늄 매트릭스 복합 재료 계면에서의 잔류 응력을 정량적으로 측정하였다. X-선 회절법으로 측정한 잔류 응력 값과 수치 해석 모델 계산 결과와 비교하였다. 모델 계산 결과보다 낮은 측정 결과를 얻었으며 이는 매트릭스의 응력 이완 또는 화이버의 basal palne sliding 현상에 기인한 것으로 추정된다.

• Journal of the Mineralogical Society of Korea
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• v.16 no.1
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• pp.65-73
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• 2003

In this study we have derived the two correction methods of hydrogen bonding distance. In case of the intermediate or long hydrogen bond(＞2.5 $\AA$), hydrogen bonding distances can be corrected by using the function d(O-H)=exp((2.173-d(O…O))/0.138)+0.958 obtained by least- squares fit to the data from the neutron diffraction at low temperatures. The valence-least-squares method is effective for the distance correction of very short hydrogen bond(<2.5 $\AA$). The distance correction is necessary for the long intermolecular hydrogen bond obtained from X-ray diffraction analysis.

• Journal of the Mineralogical Society of Korea
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• v.13 no.3
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• pp.138-146
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• 2000

Using the ultrasonic interferometry on the single crystal MgO-periclase, adiabatic bulk moduli were determined to be 163.2 GPa and 162.6 GPa from (100) and (110) lattice plane measurements, respectively. Density was measured on polycrystalline MgO by the X-ray diffraction technique. Results from this study were compared with the previously reported values. Further, the present results were converted to the isothermal bulk moduli and, then compared with the published data available including the energy dispersive X-ray diffraction result which was performed on the same single crystal MgO. The principle and techniques ultrasonic interferometry were introduced too.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.371-371
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• 2013

사파이어 단결정 웨이퍼는 제조과정에서 결정 성장 조건 및 기계적 연마에 의하여 내부적인 결함이 발생할 수 있다. 사파이어 단결정은 일반적으로 LED용 기판 재료로 사용되며, 내부결함이 발생 시 기판 위의 GaN 등 layer의 결함도 함께 증가하므로 기판의 결함을 줄이는 과정이 중요한 이슈이다. 이 과정에 X-선 토포그래피는 단결정의 내부 결함을 모니터링 하는데 있어서 매우 유용한 방법이다. 이에 본 연구에서는 사파이어 단결정 웨이퍼에 내재하는 결함 형태를 X-선 Lang 토포그래피 방법(X-ray Lang Topography)으로 이미징하여 관찰, 분석하였다. Lang 토포그래피 방법은 X-선 투과법으로 넓은 부분을 우수한 강도와 분해능으로 내부 결함을 관찰할 수 있는 장점을 지니고 있다. X-선 source는 Mo $k{\alpha}$ 1을 사용하였으며, 시료는 c-plane 사파이어 웨이퍼를 사용하였다. 사파이어 웨이퍼의 (110), (102) 회절면의 X-선 토포그래피 이미지를 통해 전위 결함의 유형에 따른 이미지 패턴의 형성 메커니즘에 대해 연구하였고, 측정 회절면과 두께, 표면 데미지에 따른 전위 결함 이미지의 변화를 확인하였다. X-선 토포그래피 이미지를 통해 단결정 c-plane 사파이어 웨이퍼의 전위 결함의 형성 메카니즘 연구와 유형별 이미지와 회절면, 두께, 표면 데미지에 따른 이미지 변화 등을 확인하였다.

• Proceedings of the Korea Crystallographic Association Conference
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• 2001.05a
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• pp.24-24
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• 2001

• Korean Journal of Crystallography
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• v.9 no.2
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• pp.143-148
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• 1998

Tris(biuret)chromium(III) Perchlorate Monohydrate (Cr(C2H5N3O2)3·(ClO4)3·H2O)의 결정 및 분자구조를 X-선 회절법으로 연구하였다. 결정의 공간군은 P, a=10.486(3) , b=11.371(5) , c=11.485(4) , α=88.70(3)o β=66.85(3)0, γ=67.11(3)o, V=1146.2(7) 3가 Z=2이다. 회절반점들의 세기는 Enraf-Noninus CAD-4 Diffractometer로 얻었으며, MoKα radiation X-선을 사용하였다. 분자구조는 직접법으로 풀었으며 최소자승법으로 정밀화하였다. 최종 신뢰도 R값은 1528개의 회절반점에 대하여 0.114이었다. Tris(biuret)chromium(III) cation은 octahedral 배열을 하고 있으며, 평균 Cr-O 결합길이는 1.94 이다. 모든 perchlorate anion은 각각 두가지 위치로 disorder되어 있다. 양이온과 음이온들은 물분자들을 포함한 수소결합들로 결합되어 결정을 이루고 있다. 양이온내의 모든 N-H가 모두 수소결합에 참여하고 있다.

• Electrical & Electronic Materials
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• v.6 no.6
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• pp.565-572
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• 1993

LPE(liquid phase epiraxy)법으로 성장시킨 $Al_{x}$ Ga$_{1-x}$As (0.15.leq.x.leq.0.67) 에피층의 구조적 특성을 이중결정 X-선 회절장치를 사용하여 조사하였다. GaAs기판과 $Al_{x}$ Ga$_{1-x}$As 에피층의 격자상수 차이로 인해 피이크가 분리되었고 이는 조성비가 증가함에 따라 선형적으로 증가하였다. 그리고 조성비는 Vegard의 법칙으로 구한 값과 기판 및 에피층 피이크 사이 각도분리(.DELTA..theta.)를 측정함으로써 구한 값이 일치하였으며 이때 관계식은 .DELTA..theta.=354.x을 얻었다. 또한 성장된 에피층은 compressive stress를 받고 있으며 조성비(x)가 0.15에서 0.67로 증가함에 따라 응력은 증가하였으며 그리고 피이크의 반치폭으로 부터 계산된 전위밀도가 역시 증가하였다.

• 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 Korean Chemical Society
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• v.40 no.9
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• pp.607-614
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• 1996

The structural changes and dielectric properties of Pb1-x(Na1/2La1/2)x(Mg1/3Nb2/3)O3 compounds substituted by 0∼50 mol.% of Na+/La3+ mixed ions were investigated by X-ray diffraction method, IR and Raman spectroscopy, and LCR meter. The amount of perovskite phase increased with the increases of Na+/La3+ substituents and sintering temperatures. Although the superlattice lines due to 1:1 ordering were not detected by X-ray diffraction method, it was found, from the Raman spectroscopy and the increase of diffuseness coefficient, that the ordering behavior was related to the decrease of A site ion size. Dielectric properties in Pb1-x(Na1/2La1/2)x(Mg1/3Nb2/3)O3 were affected by the amount of perovskite phase, grain size, and density. The phase transitions were broadened and phase transition temperatures were lowered by the increase of Na+/La3+ ions.