• Corrosion Science and Technology
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• v.22 no.1
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• pp.36-43
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• 2023

Single-crystal Ni-rich NCM is a material that has drawn attention in the field of lithium-ion batteries due to its high energy density and long cycle life. In this study, we investigated the properties of single-crystal NCM 811 and its potential for use in lithium-ion batteries. High-quality single crystals of NCM 811 were successfully synthesized by crystal growth via a flux method. The single-crystal nature of the samples was confirmed through detailed characterization techniques, such as scanning electron microscopy and x-ray diffraction with Rietveld refinement. The crystal structure and electrochemical performances of the single-crystal NCM 811 were analyzed and compared to its poly-crystal counterpart. The results indicated that single-crystal NCM 811 had electrochemical performance and thermal stability superior to poly-crystalline NCM 811, making it a suitable candidate for high-performance batteries. The findings of this study contribute to a better understanding of the characteristics and potential of single-crystal NCM 811 for lithium-ion batteries.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.74-75
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• 2021

This study attempted to study the setting time and compressive strength according to the sugar type through XRD. Setting time was found to be delayed the most when mixing white sugar, and setting time was promoted when mixing Saccharin and Aspartame. It was found that when white sugar and Grosvener siraitia were mixed, the compressive strength was higher than that of Control. Aspartame the age passed, C₃S decreased and Ca(OH)₂ increased.

• Journal of Ceramic Processing Research
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• v.21 no.3
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• pp.319-325
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• 2020

Thermoelectric and transport properties of FeVSb1-xSnx (0.015<x<0.055) alloys were studied with respect to types of vials(zirconia and stainless steel), Sn contents and temperature. The results were compared with the previously studied samples synthesized by using stainless-vial. All the designated compositions in current work were prepared via a mechanical alloying process using a zirconia vial. Vacuum hot pressing was conducted to consolidate the mechanically alloyed powders. F43m symmetry was being confirmed from the Rietveld refinement pattern. The phase transitions during the milling process and vacuum hot processing were investigated and the results exhibited near single half-Heusler phases with a minor portion of the second phase within the matrix. The Second phase might play a role to reduce thermal conductivity. Electrical conductivity exhibited semi-metallic behavior in all the temperature range. Carrier concentrations are found to be decreased with the increasing Sn contents and the FeVSb0.955Sn0.045 specimen showed the ZTmax of 0.23 at 757 K.

• Journal of the Mineralogical Society of Korea
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• v.16 no.3
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• pp.223-232
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• 2003

The co-precipitation method is applied to synthesize the cathode material Li[L $i_{x}$M $n_{1-x-y}$C $r_{y}$ ] $O_2$ for lithium rechargeable batteries at $650^{\circ}C$ (CR650) and 8$50^{\circ}C$ (CR850), respectively. Rietveld indices indicate that $R_{wp}$ with respect to $R_{exp}$ ( $R_{wp}$/ $R_{exp}$) are 9.2%/10.1% for CR650 and 15.9%/9.76% for CR850, respectively. $R_{B}$ and S (GofF) shows 10.9%, 8.54% and 1.9, 1.6, respectively. Rietveld structure refinement reveals that layer structure of LiMn $O_2$ (R3m) coexists with lower symmetry of Li[L $i_{1}$3/M $n_{2}$3/] $O_2$ (C2/c) due to superlattice ordering of Li and Mn in metal-transition containing layers. Unit-cell parameters are calculated as a=2.8520(2)$\AA$, c=14.248(2)$\AA$, V=100.40(l)$\AA^3$ for CR650, and a=2.8504(1)$\AA$, c=14.2371(7)$\AA$, V=100.179(8)$\AA^3$ for CR850. Final chemistry is obtained as Li[L $i_{0.35}$M $n_{0.56}$C $r_{0.09}$] $O_2$ (CR650) and Li[L $i_{0.27}$M $n_{0.61}$C $r_{0.13}$] $O_2$ (CR850), respectively.y...y..vely.y...y..

• Journal of the Korean Magnetics Society
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• v.18 no.2
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• pp.67-70
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• 2008

$Tb_2Bi_1Ga_xFe_{5-x}O_{12}$(x=0, 1) fabricated by sol-gel and vacuum sealed annealing process. $Tb_2Bi_1Ga_xFe_{5-x}O_{12}$(x=0, 1) have been studied by x-ray diffraction(XRD), vibrating sample magnetometer, and $M\ddot{o}ssbauer$ spectroscopy. The crystal structures were found to be a cubic garnet structure with space group Ia3d. The determined lattice constants $a_0$ of x = 0, and 1 are $12.497\AA$, and $12.465\AA$, respectively. The distribution of gallium and iron in $Tb_2Bi_1Ga_xFe_{5-x}O_{12}$ is studied by Rietveld refinement. Based on Rietveld refinement results, the terbium and bismuth ions occupy the 24c site, iron ions occupy the 24d, l6a site, and nonmagmetic gallium ions occupy the 16a site. In order to verify the magnetic site occupancy of iron and gallium, we have taken $M\ddot{o}ssbauer$ spectra for $Tb_2Bi_1Ga_xFe_{5-x}O_{12}$(x=0, 1) at room temperature. From the results of $M\ddot{o}ssbauer$ spectra analysis, the absorption area ratios of Fe ions for $Tb_2Bi_1Fe_5O_{12}$ on 24d and 16a sites are 60.8 % and 39.2 %, respectively, and the absorption area ratios of Fe ions for $Tb_2Bi_1Fe_5O_{12}$ on 24d and 16a sites are 74.7 % and 25.3 %, respectively. It is noticeable that all of the nonmagnetic Ga atoms occupy the 16a site by vacuum annealing process.

• Journal of the Mineralogical Society of Korea
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• v.19 no.1 s.47
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• pp.15-29
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• 2006

Synthetic Mn-tourmalines (tsilaisite) were obtained by hydrothermal synthesis under the condition of 2 Kbar, $375{\sim}700^{\circ}C$, and 50 day-run-time with complete substitution of Mg in dravite by Mn (Mn%=0, 25, 50, 75, and 100%). They are all 6 samples containing Mn-tourmaline with some amounts of albite, spessartine, rhodocrosite, phlogopite etc, showing different synthetic condition of temperature and Mn composition. Synthetic Mn-tourmalines are of site deficiency in X-site ($0.53{\sim}0.68$) more than that of natural ones (approx. $0.2{\sim}0.3$) and show Mn cations occupying Y-site less than expected with initial experiments, leading to failure in synthesis of end-member tsilaisite. Rietveld structural refinements reveal that $R_{wp}$ ($R_{p}/R_{exp}$) is in the range of 13.35 and 18.62%, $R_{B}$ and S (CofF) are $4.85{\sim}6.25%$ (S-18: 8.57%), $1.31{\sim}1.59$ (S-18: 1.81), respectively. Unit cell parameters (space group R3m, z=3) are ${\alpha}=15.8994\;{\AA}$ and $c=7.1846\;{\AA}$ in average (S-18: ${\alpha}=15.9491\;{\AA},\;c=7.1773\;{\AA}$). Average bond lengths of and are $2.67{\sim}2.69\;{\AA}$ (S-18: $2.65\;{\AA}$) and $2.00{\sim}2.02\;{\AA}$ (S-18: $1.96\;{\AA}$), respectively. Ditrigonality (${\delta}$) are in the range of 0.022 and 0.031 (S-18: 0.061), indicating degrading symmetry with increase of Mn content.

• Korean Chemical Engineering Research
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• v.49 no.5
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• pp.657-663
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• 2011

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 $1.0Al_2O_3:1.0P_2O_5:0.76SDA:45H_2O$ 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 $^{27}Al$ and $^{31}P$ MAS NMR of the sample suggested that Al and P were incorporated into the framework of the aluminophosphate.

• Journal of Conservation Science
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• v.32 no.3
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• pp.403-416
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• 2016

Mineral composition and content of 22 Korean Dancheong pigment products were obtained by Rietveld quantitative analysis. Jubosa, Hwang, Seokrok, Seokcheong and Hobun consist of pure cinnabar, orpiment, malachite, azurite and calcite (or aragonite), respectively. Whereas Seokganju, Hwangto, Noerok, Lapis lazuli, Baekto and Cockie hobun mainly consist of hematite, goethite, celadonite, lazurite, kaolin mineral and portlandite, respectively. And they all consist of soil minerals (quartz, feldspar, sericite and vermiculite) and filler minerals in the industry field (calcite, gypsum and anhydrite) at a different content. Quantitative XRD proved more useful method to determined exact mineral composition and content than chemical or microscopical data. If this method utilize for specification of natural pigment product, it is considered to be applicable in restoration technology and conservation science field.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.2
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• pp.253-258
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• 1997

The characteristics of crystal structure and phase transition with dopants ($Nb_2O_5$= 0.1~0.4 mol% and $Y_2O_3$ : 0.2~0.4 mol%) on the PTCR $BaTiO_3$ system were investigated. In the case of $Nb_2O_5$ additive, the lattice parameter of PTCR $BaTiO_3$ was changed linearly with the increasement of $Nb_2O_5$ which substituted B-site of BaTiO$_3$ and the lattice parameter of c-axis decreased abruptly at 0.3 mol%. These phenonmena were assumed to originate from the distortion of octahedron and we could confirm that the change of lattice parameter accorded with the characteristics of the phase transition temperature. $Y^{3+}$ ions substituted both of A- and B-site until the 0.3 mol% addition, but $Y^{3+}$ substitution preferred A- to B-site above 0.3 mol%. This was affirmed by the variation ,of lattice parameter and the characteristics of phase transition. It also was found that $Y^{3+}$ions in the A-site substituted both of $Ba^{2＋}$ and $Ca^{2＋}$ ions with equal ratio by Rietveld method.

• Journal of the Korean Magnetics Society
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• v.20 no.5
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• pp.187-190
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• 2010

$Sn_{0.99}{^{57}Fe}_{0.01}O_2$ prepared by a sol-gel method, and studied by x-ray diffractometer, vibrating magnetometer, Superconducting quantum interference devices and M$\ddot{o}$ssbauer spectroscopy. the crystal structure were found to be a rutile tetragonal structure with space group $P4_2$/mnm, and oxygen deficiency are 5.6 % by Rietveld refinement. magnetization value were $M_s=1.95{\times}10^{-2}{\mu}_B/Fe$ at room temperature, and Curri-weiss temperature were and ${\theta}_{cw}$ = 18 k, measurement of VSM and SQUID, respectively. Mssbauer spectra of $Sn_{0.99}{^{57}Fe}_{0.01}O_2$ have been Sextet taken at various temperatures ranging from 4.2 K to RT, and isomer shift value $\delta$ = 0.18~0.36 mm/s of $^{57}Fe$ ion site all of the temperature range the state shows ferric.