Application of Inverse Pole Figure to Rietveld Refinement: I. Rietveld Refinement of Copper Sheet using X-ray Diffraction Data

Kim, Yong-Il,Jung, Maeug-Joon,Kim, Kwang-Ho The Korean Ceramic Society 2000 The Korean journal of ceramics Vol.6 No.3

Both the X-ray diffraction data of the normal direction in the sample orientation and the pole figure data of three reflections, (111), (200) and (220), were used to do the Rietveld refinement for the copper sheet prepared by a cold rolling process. The agreement between calculated and observed patterns was not satisfactory, which was attributed to the preferred orientation effect of the copper sheet. The Rietveld refinement for the copper sheet could be done successfully by applying the pole density of each reflection obtained from the corresponding inverse pole figure to the X-ray diffraction data of the normal direction. The R-weighted pattern, $R_{wp}$ was 12.99% and the goodness-of-fit indicator, S, was 3.68.

Application of Inverse Pole Figure to Rietveld Refinement: I. Rietveld Refinement of Copper Sheet using X-ray Diffraction Data

Yong-Il Kim,Maeug-Joon Jung,Kwang-Ho Kim 한국세라믹학회 2000 The Korean journal of ceramics Vol.6 No.3

Both the X-ray diffraction data of the normal direction in the sample orientation and the pole figure data of three reflections, (111), (200) and (220), were used to do the Rietveld refinement for the copper sheet prepared by a cold rolling process. The agreement between calculated and observed patterns was not satisfactory, which was attributed to the preferred orientation effect of the copper sheet. The Rietveld refinement for the copper sheet could be done successfully by applying the pole density of each reflection obtained from the corresponding inverse pole figure to the X-ray diffraction data of the normal direction. The R-weighted pattern, Rwp, was 12.99% and the goodness-of-fit indicator, S, was 3.68.

Application of Inverse Pole Figure to Rietveld Refinement: III. Rietveld Refinement of $SnO_2$ Thin Film using X-ray Diffraction Data

Kim, Yong-Il,Jung, Maeng-Joon,Kim, Kwang-Ho The Korean Ceramic Society 2000 The Korean journal of ceramics Vol.6 No.4

The SnO$_2$film was deposited on a corning glass 1737 substrate by plasma enhanced chemical vapor deposition using a gas mixture of SnCl$_4$, $O_2$, and Ar. The film thickness was measured using $\alpha$-step and was about 9400$\AA$. The conventional X-ray diffractometry and pole figure attachment were used to refine the crystal structure of SnO$_2$ thin film. Six pole figures, (200), (211), (310), (301), (321), and (411), were measured with CoK$_\alpha$ radiation in reflection geometry. The X-ray diffraction data were measured at room temperature using CuK$_\alpha$ radiation with graphite monochromator. The agreement between calculated and observed patterns for the normal direction of SnO$_2$ thin film was not satisfactory due to the severely preferred orientation effect. The Rietveld refinement of heavily textured SnO$_2$ thin film was successfully achieved by adopting the pole density distribution of each reflection obtained from the inverse pole figure as a correction factor for the preferred orientation effect. The R-weighted pattern, R$_wp$, was 15.30%.

Quantitative Mineral Identification of Alluvial Soils Using the Rietveld Refinement: Sequential vs. Batch Refinement

( Bongsu Chang ),( Seon Yong Lee ),( Young Jae Lee ),( Yeowon Yoon ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

Information of mineral phases in soils is essential for understandng physicochemical characteristics of soils in unsaturated zone. In this study, mineral identification and quantitative phase analysis were performed for alluvial soils by Rietveld refinement with X-ray powder diffraction (XRPD) data. For systematic analysis, a grid soil sampling method was adopted for the target area of 100 m width and 80 m length at Deokso, Gyeonggi Province. Core samples for soils were collected at intervals of 20 m with a depth of 2 m by a geotechnical drilling rig. For the XRPD analysis, clay size particles were only prepared by a wet sieving and an oven drying. In the process of refinement, two different approaches were applied to determine which approaches yield more quantitative results. One is to increase the number of constituent minerals step by step after optimization for a single mineral. The other is to perform a batch optimization on all constituent minerals at once. As a result of the refinements, the weighted residual square sum (Rwp) of less than 10% is obtained on average in both cases, indicating a reliable result. Further significance test revealed that these results are indistinguishable. Although the both approaches are statistically acceptable for a set of mineral phases, the spatial abundances of individual minerals are not consistent with each other. This would show that goodness of fit is independent from getting the correct solution. Therefore, it is necessary to cross a check with the X-ray fluorescence data.

단결정 AlN의 미세구조 분석 및 어닐링 공정이 결정성에 미치는 영향

김정운,배시영,정성민,강승민,강성,김철진,Kim, Jeoung Woon,Bae, Si-Young,Jeong, Seong-Min,Kang, Seung-Min,Kang, Sung,Kim, Cheol-Jin 한국결정성장학회 2018 한국결정성장학회지 Vol.28 No.4

PVT(Physical vapor transport)법은 고품질의 대면적 웨이퍼를 생산하기에 이점을 가져 질화물계 반도체의 상용화를 위해 많은 연구가 진행되고 있는 단결정 성장 방법이다. 하지만 복잡한 공정 변수들로 인하여 비평형적인 성장 조건을 갖게 될 경우 수많은 결함들이 발생하게 된다. 결정성장 후 어닐링 공정은 결정성 개선을 위해 널리 사용된다. 효과적인 결정성 개선을 위해서는 적절한 온도, 압력과 시간을 설정하는 게 중요하다. 본 연구에서는 PVT법으로 성장된 AlN 단결정 및 어닐링 조건에 따른 단결정의 결정 미세구조 변화를 X-ray topography, Electron Backscattered Diffraction(EBSD), Rietveld refinement를 통해 분석하였다. Synchrotron Whitebeam X-ray topography 분석 결과 어닐링을 진행하지 않은 단결정에 2차상 및 sub grain, impurity가 존재하였으며 이로 인해 결정성이 저하되는 것을 확인 할 수 있었다. EBSD 결과 어닐링을 진행한 시편의 경우 결정립수가 증가함과 동시에 basal plane의 뒤틀림이 일어나는 것을 관찰할 수 있었다. Rietveld refinement 결과 일부 격자들이 a, b, c축 방향으로 응력을 받아 변형된 것으로 분석되었다. 이는 어닐링 과정 중 hot zone 내의 상하 온도구배에 의해 발생한 응력으로 결정립 방향의 뒤틀림이 일어날 뿐만 아니라 격자 상수가 달라진 것으로 분석된다. PVT (Physical Vapor Transport) method has advantages in producing high quality, large scale wafers where many researches are being carried out to commercialize nitride semiconductors. However, complex process variables cause various defects when it had non-equilibrium growth conditions. Annealing process after crystal growth has been widely used to enhance the crystallinity. It is important to set appropriate temperature, pressure, and annealing time to improve crystallinity effectively. In this study, the effect of the annealing conditions on the crystalline structure variation of the AlN single crystal grown by PVT method was investigated with synchrotron whitebeam X-ray topography, electron backscattered diffraction (EBSD), and Rietveld refinement. X-ray topography analysis showed secondary phases, sub-grains, impurities including carbon inclusion in the single crystal before annealing. EBSD analyses identified that sub-grains with slightly tilted basal plane appeared and the overall number of grains increased after the annealing process. Rietveld refinement showed that the stress caused by the temperature gradient during the annealing process between top and bottom in the hot zone not only causes distortion of grains but also changes the lattice constant.

피페리딘 구조유도분자를 이용한 알루미노포스페이트 제올라이트 합성: 피페리딘 구조유도분자가 결정구조 형성에 미치는 영향

신혜선 ( Hye Sun Shin ),장익준 ( Ik Jun Jang ),신나라 ( Na Ra Shin ),주빛나 ( Bit Na Ju ),조성준 ( Sung June Cho ) 한국화학공학회 2011 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.49 No.5

Structure directing agent(SDA) containing piperidine moiety such as piperidine(PI), 2-methylpiperidine(MPI), 2,6-dimethylpiperidine(DMPI) and 2,2,6,6,-tetramethylpiperidine(TMPI), respectively has been utilized to synthesize aluminophosphate zeolite using hydrothermal method. The gel composition was (l.0)Al2O3:(1.0)P2O5:0.76SDA:(45)H2O and the hydrothermal heating was performed in an oven at 443 K and for 7 days at static mode. The obtained zeolitic material contained a lamellar structure when PI was used as the SDA. With a progressive increase of the SDA size, various structures of aluminophosphate including AlPO-5 of AFI structure were obtained. The aluminophosphate of SAS structure was formed when the largest TMPI was utilized as the SDA, which was confirmed by the Rietveld refinement. The result of 27 AI and 31P MAS NMR of the sample suggested that Al and P were incorporated into the framework of the aluminophosphate.

Luminescent Properties of RbSrPO₄:Eu²⁺ Phosphors for Near‐UV‐Based White‐Light‐Emitting Diodes

Yim, Dong Kyun,Song, Hee Jo,Roh, Hee‐,Suk,Kim, Seung‐,Joo,Han, Byung Suh,Jin, Yun‐,Ho,Hong, Hyun‐,Seon,Kim, Dong‐,Wan,Hong, Kug Sun WILEY‐VCH Verlag 2013 European journal of inorganic chemistry Vol.2013 No.26

<P><B>Abstract</B></P><P>A phosphor based on a phosphate host matrix, RbSrPO<SUB>4</SUB>:Eu<SUP>2+</SUP> (RSP), was synthesized by a conventional solid‐state reaction, and the crystal structure of the RSP host material was investigated by Rietveld refinement. The RSP phosphor could be excited efficiently by light in the 220–430 nm UV/Vis range and exhibited a highly intense emission peak at 450 nm. We discovered the effect of the activated Eu<SUP>2+</SUP> concentration and the concentration quenching mechanism. Also, light absorption and quantum efficiency of the RSP phosphor were measured when excited in the near‐UV region. Finally, the effect of temperature on the photoluminescence emission intensity of the RSP phosphor and its thermal activation energy were investigated. All of these characteristics indicate that this phosphor has potential for use in near‐UV‐based white LEDs.</P>

Fe 이온 치환 beta-tricalcium phosphate의 하소 온도에 따른 미세구조 및 분해 특성

유경현,김현진,선우경,윤석영 한국결정성장학회 2020 한국결정성장학회지 Vol.30 No.6

β-삼인산칼슘(β-tricalcium phosphate, β-TCP, Ca3(PO4)2)은 뼈와 유사한 성분을 가지는 인산 칼슘계 세라믹 중 하나로, 생분해성과 골 전도성을 가지고 있어 골 대체재 등으로 다양하게 사용된다. 이러한 β-TCP의 생체 활성과 골유도성을향상시키기 위해 다양한 이온 치환 연구가 진행되어왔으며 그 중 철 이온은 필수 미량 원소로 체내에서 다양한 기능을 한다. 본 연구에서는 β-TCP에 철 이온이 치환되었을 때 열처리 온도에 따른 구조의 변화를 분석하고, 이에 따른 생분해 특성을 평가하였다. 또한 분해 후의 구조를 분석하여 분해 거동을 확인하였다. 철 이온을 치환한 β-TCP는 공침법으로 합성을하였고, 925℃와 1100℃에서 하소 처리를 실시하였다. X-선 회절 분석과 Rietveld refinement를 이용하여 구조 분석을 실시하였다. 철 이온은 온도에 따라 Fe2+또는 Fe3+ 상태로 바뀌기 때문에 β-TCP에 치환되었을 때 열처리 온도에 따라 치환 위치(Ca(4), Ca(5))가 바뀌고, 1100℃에서 열처리를 실시한 철 이온 치환 β-TCP의 분해 속도가 가장 빨랐다. 또한 세포 증식특성이 향상된 것을 통해 β-TCP에 철 이온을 치환하는 것이 생체적합성과 생체 활성 특성을 향상시키고 골 결손부 회복등 더욱 다양한 분야에 사용될 수 있을 것으로 기대된다. β-Tricalcium phosphate (β-TCP, Ca3(PO4)2) is a kind of biodegradable calcium phosphate ceramics with chemicaland mineral compositions similar to those of bone. It is a potential candidate for bone repair surgery. To improve thebioactivity and osteoinductivity of β-TCP, various ions doped calcium phosphate have been studied. Among them, Iron is atrace element and its deficiency in the human body causes various problems. In this study, we investigated the effect of Feions on the structural variation, degradation behavior of β-TCP. Fe-doped β-TCP powders were synthesized by the coprecipitationmethod, and the heat treatment temperature was set at 925 and 1100℃. The structural analysis was carried out by Rietveld refinement using the X-ray diffraction results. Fe ions existed in a different state (Fe2+ or Fe3+) with different heat treatment temperatures, and the substitution sites (Ca-(4) and Ca-(5)) also changed with temperature. The degradation rate was fastest at Fe-doped β-TCP with heated at 1100℃. The cell viability behavior was also enhanced with the substitution of Fe ions. Therefore, the substitution of Fe ion has accelerated the degradation of β-TCP and improved the biocompatibility. It could be more utilized in biomedical devices.

Phase formation and luminescence properties of ternary solid-solution among tetragonal systems

Unithrattil, Sanjith,Kim, Ha Jun,Im, Won Bin ELSEVIER SCIENCE 2019 JOURNAL OF ALLOYS AND COMPOUNDS Vol.798 No.-

<P><B>Abstract</B></P> <P>A new strategy for developing solid-solution compounds from three constituent compounds was analyzed. Using this strategy, a series of yellow-light-emitting phosphors derived from ternary solid-solution host compositions were prepared using solid-state synthesis. Three vertex members, Sr<SUB>3</SUB>SiO<SUB>5</SUB> (space group <I>P</I>4/<I>ncc</I>), Sr<SUB>3</SUB>AlO<SUB>4</SUB>F (space group <I>I</I>4/<I>mcm</I>), and LaSr<SUB>2</SUB>AlO<SUB>5</SUB> (space group <I>I</I>4/<I>mcm</I>), were selected from similar crystal structures with slightly different symmetries. The crystallization space group of the composition was found to be dependent on the end members, and from the vertex of the ternary plot to the centroid, the composition assumed the space group that was more tolerant toward substitutions. All the compositions, except those lying at the periphery of the ternary plot, formed a single phase and emitted yellow light when activated with Ce<SUP>3+</SUP> ions. The luminescence properties of the 28 selected compositions on the ternary plot were analyzed. The compound that was formed from a 1:2:1 ratio of end members assumed a <I>I</I>4/<I>mcm</I> structure and showed the highest-intensity emission. Phosphor derived from the developed host lattice was analyzed for application in solid-state lighting devices by preparing a white-light emitting device.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Phase formation in ternary solid-solutions of tetragonal systems. </LI> <LI> Tetragonal structure Sr<SUB>3</SUB>SiO<SUB>5</SUB>, LaSr<SUB>2</SUB>AlO<SUB>3</SUB> and Sr<SUB>3</SUB>AlO<SUB>4</SUB>F are investigated in the preparation of ternary solid solution. </LI> <LI> Structural analysis of all the selected compositions was carried out using the Le Bail method. </LI> <LI> The detailed structural analysis of selected compositions was performed via Rietveld refinement. </LI> <LI> Ternary solid solution present great color tunability in wLED fabrication. </LI> </UL> </P>

고상법에 의한 $Li_{1+x}Mn_2O_4$ ($0\leqx\leq0.075$) 의 결정구조와 전기화학적 특성

박종광,고건문,임성훈,황종선,한병성 한국전기전자재료학회 2001 전기전자재료학회논문지 Vol.14 No.5

We have investigated the L $i_{1+x}$M $n_2$ $O_4$system as a cathode material for lithium rechargeable batteries. To improve the cycle performance of spinel LiM $n_2$ $O_4$ as the cathode of 4V class lithium secondary batteries, spinel phase L $i_{1+x}$M $n_2$ $O_4$(x=0, 0.025, 0.05, 0.075) was prepared at 75$0^{\circ}C$ for 48h. The preparation of L $i_{1+x}$M $n_2$ $O_4$ from L $i_2$ $O_3$ and Mn $O_2$ under air is studied. The compounds were synthesized by using solid-state reaction. Structural refinements were carried out with a Rietveld-refinement program. Electrochemical properties were examined using the Li/L $i_{1+x}$M $n_2$ $O_4$ cells. The capacity of L $i_{1+x}$M $n_2$ $O_4$ decreases with increases lithium content, while the cycle life improves. The initial discharge capacity are 118mAh/g and 116mAh/g for LiM $n_2$ $O_4$ decreases with increases lithium content, while the cycle life improves. The initial discharge capacity are 118mAh/g and 116mAh/g for LiM $n_2$ $O_4$ and L $i_{1.025}$M $n_2$ $O_4$, respectively.pectively.