• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.283-287
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• 2003

Crystal structure of $(Ba_{1-x}La_x)[Mg_{(1+x)/3}Nb_{(2-x)/3}]O_3$ (BLMN) ceramics with $0{\leq}x{\leq}1$ was investigated using synchrotron X-ray powder diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). When La content, x, is above 0.1, the 1:2 ordered hexagonal structure found in $Ba(Mg_{1/3}Nb_{2/3})O_3$ (BMN) was transformed into 1:1 ordered cubic structure. The 1:1 ordered cubic structure was maintained up to x=0.7. However, when x exceeded 0.7, BLMN was transformed 1:1 ordered structure which has cation displacement and in-phase and anti-phase tilt of octahedra.

• Bulletin of the Korean Chemical Society
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• v.19 no.10
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• pp.1095-1099
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• 1998

The crystal structure of an acetylene sorption complex of dehydrated fully Mn(Ⅱ)-exchanged zeolite X, Mn46Si100Al92O384·30C2H2 (a=24.705(3) Å) has been determined by single-crystal X-ray diffraction techniques. The structure was solved and refined in the cubic space group Fd3 at 21(l) ℃. The complex was prepared by dehydration at 380 ℃ and 2 x 10-6 Torr for 2 days, followed by exposure to 300 Torr of acetylene gas for 2 h at 24 ℃. The structure was refined to the final error indices, R1=0.060 and R2=0.054 with 383 reflections for which I > 3σ(Ⅰ). In the structure, Mn2+ ions are located at two different crystallographic sites; sixteen Mn2+ ions at site I are located at the centers of the double six rings and thirty Mn2+ ions are found at site Ⅱ in the supercage, respectively. Each of these latter Mn2+ ions is recessed ca. 0.385(2) Å into the supercage from its three-oxygen plane. Thirty acetylene molecules are sorbed per unit cell. Each Mn2+ ion at site Ⅱ lies on a threefold axis in the supercage of the unit cell, close to three equivalent trigonally arranged zeolite framework oxygen atoms (Mn(Ⅱ)-O=2.135(9) Å) and symmetrically to both carbon atoms of a C2H2 molecules. At these latter distances, the Mn(Ⅱ)-C interactions are weak (Mn(Ⅱ)-C=2.70(5) Å), probably resulting from electrostatic attractions between the divalent cations and the polarizable π-electron density of the acetylene molecules.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.16 no.1
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• pp.8-11
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• 2006

The magnetic properties and crystal structures of $Sm_yGd_{2-y}Fe_{17-x}Si_x$ alloys ($0\leq\;x\leq2\;and\;y=0\~1.67$) have been investigated using x-ray diffraction and magnetic measurements. The $Sm_yGd_{2-y}Fe_{17-x}Si_x$ specimens were crystallized to the rhombohedral $Th_2Zn_{17}-structure$ with less than $5mol\%$ of impurities. The unit cells of the mixed rare-earth samples are smaller than those of $Sm_2Fe_{17}\;and\;Gd_2Fe_{17}.$ For example, the $T_c\;of\;SmGdFe_{17}\;(255^{\circ}C)$ is approximately 160 and $800^{\circ}C)$ higher than that of $Sm_2Fe_{17}\;and\;Gd_2Fe_{17},$ respectively. The $T_cs$ measured for $Sm_yGd_{2-y}Fe_{17-x}Si_x$ samples, 280 to $290^{\circ}C)$, are among the highest values observed for a $R_2Fe_{17-x}M_x$ intermetallic where M is a substituent other than cobalt.

• Bulletin of the Korean Chemical Society
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• v.20 no.7
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• pp.791-795
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• 1999

The crystal structure of a cyclopropane sorption complex of dehydrated fully Ca (2+) -exchanged zeolite X, Ca46Si100Al92O384· 30C3H6 (a = 24.988(4) Å), has been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd3 at 21(1)℃. The crystal was prepared by ion exchange in a flowing stream of 0.05M aqueous Ca(NO3)2 for four days, followed by dehydration at 460℃ and 2×10 (-6) Torr for two days, and exposure to 100 Torr of cyclopropane gas at 21(1)℃. The structure was determined in this atmosphere and refined to the final error indices R1 = 0.068 and R2 = 0.082, with 373 reflections for which I > 3σ (I). In this structure, Ca 2+ ions are located at two crystallographic sites. Sixteen Ca 2+ ions fill the octahedral sites I at the centers of the hexagonal prisms (Ca-O = 2.412(9)Å). The remaining 30 Ca 2+ ions are at sites Ⅱ; each extends 0.46Å into the supercage (an increase of 0.16Å upon C3H6 sorption) where it coordinates to three trigonally arranged framework oxygens at 2.311(8)Å. Each of the 30 cyclopropane molecules was found to complex to Ca 2+ ions at site II by the induced dipole interaction (Ca-C = 2.99(4)Å). All carbon atoms in each cyclopropane molecule are equivalent and equidistant from Ca 2+ ions at site II with which they are associated.

• Korean Journal of Pharmacognosy
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• v.27 no.3
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• pp.207-211
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• 1996

Cumambrin A has been isolated from the dried flowers of Chrysanthemum boreale Makino. The complete $^1H$ and $^{13}C$ NMR assignment of cumambrin A was achieved from two-dimensional $^1H$-$^1H$ COSY and $^{13}C$-$^1H$ COSY spectra with the aid of homonuclear and heteronuclear double resonance experiments. The its structure has been verified by single crystal X-ray diffraction.

• Journal of the Korean Vacuum Society
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• v.4 no.S2
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• pp.30-33
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• 1995

By using X-ray double crystal diffraction technique the multilayer structure composed of glass membrane, platinum film and $\alpha Al_2O_3$ substrate has been studied. It is found the stress is produced in the film by thermal mismatch within multilayer materials. The measuring results of thin film platinum resistors show that the stress were induce resistance change of device and different stress status will produce add resistance in different direction. Selecting proper glass material can make opposite stress in Pt film and opposite add resistance due to thermal mismatch. The reliability of Pt resistor has been improved with method of this stress compensation.

• Archives of Pharmacal Research
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• v.8 no.1
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• pp.1-6
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• 1985

The crystal structure or $\gamma$-hydroxy-$\betha$-aminobutyric acid was determined by MULTAN system with X-ray intensity data on a diffractometer and refined by the least-squares method to an R-value 0.034 for 711 reflections. The crystals were orthorhombic, space group $P2_{1}2_{1}2_{1}$, Z = 4, with a = 10.220, b = 8.257 and c = 6.556$\AA$. The molecule takes the zwitterionic form and skeletal conformation is trans-transform. The molecules are held together by intra-and intermolecular NH-O and OH--O hydrogen bonds.

• Journal of Korea Foresty Energy
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• v.18 no.2
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• pp.62-69
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• 1999

Lignin in wood cell walls influeced the transformation of the cellulose crystal structure during mercerization. Samples of sound and decayed woods by white rot fungus of Quercus mongolica were treated with 20% aquous NaOH solution, followed by washing and drying, and delignified. The effect of delignification on cellulose structure was investigated by a series of an X-ray diffraction analysis and ultraviolet(UV) microscopy. Delignification of alkali-treated woods did not influence their cellulose crystal structures. It may be concluded that lignin prevents the swelling of wood cellulose during mercerization and restrain the intermingling of cellulose chains.

• Food Science and Biotechnology
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• v.18 no.2
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• pp.546-551
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• 2009

The objective of this study was to investigate Fourier transform infrared (FT-IR) spectrometry and the X-ray diffraction (XRD) characterization of melanoidins formed from glucose and fructose with amino acid enantiomers in the Maillard reaction. Before dialysis, FT-IR spectroscopy of all the samples showed that the characteristic absorption intensities appeared as a broad and intense band of the stretching vibration of the -OH group at 3,400/cm for a high pH. The absorption bands of the melanoidins sharply decreased in intensity after dialysis as compared to those before dialysis. In particular, the absorption bands at 992 and 575/cm disappeared. The XRD confirmed that the crystal structure of the melanoidins disappeared after dialysis and a new crystal structure was formed at 9 and $28^{\circ}$ ($2{\theta}$. In particular, broad diffraction peaks were formed in the $10-21^{\circ}$ ($2{\theta}$) range for a high pH, while other sharp diffraction peaks disappeared.

• Korean Journal of Materials Research
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• v.4 no.6
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• pp.704-709
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• 1994

The $(LaS)_xCrS_2(x \approx 1.20$) of the incommensurate misfit layer was systhesized from reactant mixture of$La_S_3$,Cr and S at 1273K. Powder X-ray diffration of $(LaS)_xCrS_2(x \approx 1.20$) was indexed as a complex structure consisted with a monoclinic LaS-sublattice, a triclinic $CrS_{2}$-sublattice and their superlattice. The temperature dependence of sublattice dimension was investigated by the X-ray diffraction analysis at low temperature. The magnetic susceptibility of $(LaS)_xCrS_2(x \approx 1.20$) was measured between 77K and room temperature using a Faraday balance method. $(LaS)_xCrS_2(x \approx 1.20$) was paramagnetic on a $\sigma$-H plot at room temperature. The observed effective magnetic moment( p dr) was in fair agreement with the value calculated by spin-only contribution for $Cr^{3+}$ and spin and orbital contribution for $La^{3+}$.