• Bulletin of the Korean Chemical Society
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• v.6 no.1
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• pp.7-11
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• 1985

The crystal structure of phlorizin, a ${\beta}$ -D-glucopyranoside of a flavonoid dihydrochalcone phloretin, has been determined by single crystal diffraction methods using diffractometer data obtained by the ${\omega}-2{\theta}$ scan technique with Cu $K{\alpha}$ radiation from a crystal with space group symmetry $P2_12_12_1$ and unit cell parameters a = 4.9094 (2), b = 19.109 (1), c = 23.275 (4) $\AA$. The structure was solved by direct methods and refined by full-matrix least-squares to a final R = 0.047 for the 1697 observed reflections. The dihydrochalcone moiety is flat and fully extended. The glucose ring has the $^4C_1$ chair conformation and the conformation of the primary alcohol group is gauche-gauche. The crystal packing is dominated by an extensive hydrogen bonding pattern. There are one strong and two weak intramolecular hydrogen bonds in the phlorizin molecule.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.4
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• pp.626-631
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• 1997

AlSiCa powders were prepared from the domestic Hadong Kaolin ($Al_2O_3{\cdot}2SiO_2{\cdot}2H_2O$). As a result of the reaction of Hadong Kaolin and carbon powder at reducing atmosphere, $Al_2O_3{\cdot}SiC$ composite started to form at $1300^{\circ}C$ and completed at $1400^{\circ}C$. The optimum amount of carbon was 1:4 in mole ratio. It was found that only bright-green $\beta-SiC$ phase forms when the mixture was packed without carbon powder in alumina crucible.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.2
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• pp.275-285
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• 1996

The effect of heat-treatment on catalytic crystallization in $LI_2O-Al_2O_3-SiO_2$ glass system over its glass transition temperature was investigated. Glass composition $4Li_2O{cdot}22AL_2O_3{cdot}66SiO_2{cdot}2TiO_2{cdot}2.5ZrO_2{cdot}1.5P_2O_5{cdot}1.0Na_2O{cdot}1.0As_2O_3$ (wt%) was selected and heat-treated at different heating conditions to obtain transparent glass-ceramic. Nucleation and crystallization behaviour of this composition were estimated by differential thermal analysis (DTA) and X-ray diffractometer (XRD) and its thermal expansion coefficients were measured by Dilatometer. As a result, glass transition temperature was $730^{\circ}C$ and two maximum nucleation temperatures were estimated at $730^{\circ}C$ and 82$0^{\circ}C$ using JMA(Johson-Mehl-Avrami) equation by DTA. $ZrTiO_4$ $\beta$-Quartz solid solution and $\beta$-Spodumene crystals were identified by XRD. The optimum crystallization temperature was 92$0^{\circ}C$ and three step heating schedule was expected to be useful to obtain transparent glass-ceramic.

• Journal of the Korean Society for Heat Treatment
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• v.13 no.3
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• pp.177-182
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• 2000

The effects of betatizing and aging temperatures on the martensitic transformation characteristics in an Cu-13.4wt%Al-4.2wt%Ni single crystal have been studied. Microstructures show that the specimen betatized above $800^{\circ}C$ has only ${{\beta}_1}^{\prime}$ martensite while the specimen betatized of below $700^{\circ}C$ has two phases i.e., ${{\beta}_1}^{\prime}+{\gamma}_2$ When betatizing temperature increase from $600^{\circ}C$ upto $900^{\circ}C$, Ms and As temperatures decrease due to the dissolution of which ${\gamma}_2$ phase depletes Al content in the matrix thereafter makes the both Ms and As temperatures significantly increased. Ms and As temperatures of the specimen aged at $200^{\circ}C$ are relatively stable but those of the specimen aged at $300^{\circ}C$ are shifted rapidly with aging time, especially within the first 30min.

• Journal of the Korean Chemical Society
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• v.9 no.3
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• pp.142-147
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• 1965

The crystal structure of p-phenylenediamine dihydrochloride has been determined from X-ray oscillation and Weissenberg photographs. The crystal is triclinic, space group $C_i1-P{\bar\1},$ with cell dimensions $a = 4.38{\pm}0.02, b = 5.90{\pm}0.02, c = 8.76{\pm}0.03 {\AA}, {\alpha} = 110{\AA}1, {\beta} = 96{\pm}1\; and\; {\gamma} = 101{\pm}1^{\circ}.$ There is one molecule in the unit cell. The atomic coordinates were found by means of two-dimensional Fourier projection and ($F_o-F_c$) projection along the a, b and c axes. The structure of p-phenylenediamine dihydrochloride is discussed in relation to the structures of hexamethylenediamine dihydrochloride, hexamethylenediamine dihydroiodide and ethylenediamine dihydrochloride.

• Journal of the Korean Chemical Society
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• v.9 no.4
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• pp.174-178
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• 1965

p-Phenylenediamine dihydrobromide and p-phenylenediamine dihydrochloride are found to be isomorphous. p-Phenylenediamine dihydrobromide is triclinic with lattice parameters, $a=4.52{\pm}0.02{\AA}\;b=6.13{\pm}0.02{\AA},c=8.88{\pm}0.03{\AA},\;{\alpha}=111{\pm}1^{\circ},\;{\beta}=97{\pm}1^{\circ},\;{\gamma}=101{\pm}1^{\circ}.$ It belongs to space group $P\bar{1}$, and there is one molecule in the unit cell. The crystal structure is determined according to the method of Fourier synthesis from the electron density projections in three principal crystallographic axes. The crystal structure, thus determined is refined by the method of two-dimensional difference Fourier synthesis.

• Bulletin of the Korean Chemical Society
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• v.13 no.4
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• pp.375-381
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• 1992

In this study we have synthesized two spiro orthocarbonates, which can be polymerized with volume expansion, and determined their crystal structures. The crystal data are as follows; 3,4,10,11-Di(9,10-dihydro-9,10-ethanoanthracenyl)- 1,6,8,13-tetraoxa-6.6-tridecane 5: a = 16.898 (1), b = 9.299 (1), c = 24.359 (2) ${\AA}$, $\beta$ = 123.73 $(7)^{\circ}$, space group P21/c and R = 0.073 for 2954 reflections; compound 8: a = 15.244 (4), b = 15.293 (3), c = 10.772 (3) $\AA$, ${\beta}$ = 99.45 $(2)^{\circ}$, space group P21/c and R = 0.082 for 2346 reflections. The seven-membered rings of compound 5 are chair forms and all the six-membered rings are boat shaped. For a six-membered spiro orthocarbonate, 3,9-Di(9-fluorenylidenyl)-1,4,6,9-tetraoxa-5,5-und ecane 8, fluorene groups [C(1) atom through C(13) atom] are planar within ${\pm}0.09{\AA}$ and the six-membered rings have chair conformations. The whole molecule has pseudo-C2 symmetry. The water molecules in the crystal are linked with each other through the hydrogen bond with distance of 2.790 (20) ${\AA}$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.2
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• pp.62-67
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• 2008

An Organometallic compound, $C_{12}H_{20}B_{10}S_2Co_2$, was synthesized from o-carborane, $Cp^*Co(S_2B_2B_{10}H_{10})$ and $BH_3{\cdot}THF$. The molecular structure of this complex has been determined by X-ray diffraction. Crystallographic data: monoclinic, space group Cc, a=15.981(4) ${\AA}$, b=15.478(17) ${\AA}$, c=12.0562(17) ${\AA}$, ${\beta}=115.063(16)^{\circ}$, Z=4, V=9683(4) ${\AA}^3$. The structure was solved by direct methods and refined by full-matrix leat-squares methods to give a model with a reliability factor R = 0.0630 for 9948 reflections.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.34 no.1
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• pp.1-7
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• 2024

β-Ga₂O₃ is a material with a wide band gap of ~4.8 eV and a high breakdown-voltage of 8 MV/cm, and is attracting much attention in the field of power device applications. In addition, compared to representative WBG semiconductor materials such as SiC, GaN and Diamond, it has the advantage of enabling single crystal growth with high growth rate and low manufacturing cost [1-4]. In this study, we succeeded in growing a 10 mm thick β-Ga₂O₃ single crystal doped with 0.3 mol% SnO₂ through the EFG (Edge-defined Film-fed Growth) method using multi-slit structure. The growth direction and growth plane were set to [010]/(010), respectively, and the growth speed was about 12 mm/h. The grown β-Ga₂O₃ single crystal was cut into various crystal planes (010, 001, 100, ${\bar{2}}01$) and surface processed. The processed samples were compared for characteristics according to crystal plane through analysis such as XRD, UV/VIS/NIR/Spec., Mercury Probe, AFM and Etching. This research is expected to contribute to the development of power semiconductor technology in high-voltage and high-temperature applications, and selecting a substrate with better characteristics will play an important role in improving device performance and reliability.

• Journal of Pharmaceutical Investigation
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• v.41 no.6
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• pp.371-376
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• 2011

The objective of this work was to investigate the existence of new crystal forms of tulobuterol which is used to prevent morning asthma attacks by ${\beta}_2$ agonist and the transformation of crystal forms. Three crystal forms of tulobuterol have been isolated by recrystallization and Form 2 was transformed to Form 4 at 52% RH and 95% RH and these four crystal forms are characterized by differential scanning calorimetry (DSC), powder X-ray diffractometry (PXRD) and thermogravimetric analysis (TG). The DSC and PXRD patterns of four crystal forms of tulobuterol were different respectively. The dissolution patterns of these three crystal forms of tulobuterol were studied and they showed significant differences in the dissolution rate. After storage of 2 months at 0% RH (silica gel, $20^{\circ}C$), 52% RH (saturated solution of $Na_2Cr_2O_7{\cdot}2H_2O/20^{\circ}C$) and 95% RH (saturated solution of $Na_2HPO_4/20^{\circ}C$), Form 1 and Form 3 were not transformed. But Form 2 was transformed to Form 4 at 52% RH and 95% RH.