• Korean Journal of Materials Research
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• v.9 no.10
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• pp.1006-1011
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• 1999

B-doped hydrogenated amorphous silicon carbide (a-SiC:H) thin films were prepared by plasma-enhanced chemical-vapor deposition in a gas mixture of $SiH_4$, $CH_4$ and $B_2H_6$. Microstructures and chemical properties of a-SiC:H films grown with varing the volume ratio of $CH_4$ to $SiH_4$ were characterized with various analysis methods including scanning electron microscopy(SEM), X-ray diffractometry(XRD), Raman spectroscopy, Fourier-transform infrared (FTIR) spectroscopy. X-ray photoelectron spectroscopy(XPS), UV absorption spectroscopy and photoconductivity measurements. While Si:H films grown without $CH_4$ showed amorphous state, the addition of $CH_4$ during deposition enhanced the development of a microcrystalline phase. By introducing C atoms into the film, Si-Si and Si--$\textrm{H}_{n}$ bonds of a -Si:H films were gradually replaced by Si-C, C-C, and Si--$\textrm{C}_{n}\textrm{H}_{m}$ bonds. Consequently, the electrical resistivity and optical bandgap of a-SiC:H films were increased with the C concentration in the film.

• Journal of the Korean Chemical Society
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• v.20 no.1
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• pp.19-34
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• 1976

The crystal structure of sodium sulfisoxazole hexahydrate, $C_{11}H_{12}N_3O_3SNa{\cdot}6H_2O$,has been determined by X-ray diffraction method. The compound crystallizes in the monoclinic space group $$P2_1}c$$ with a = 15.68(3), b = 7.70(2), c = 17.94(4)${\AA}$, ${\beta}$ = $118(2)^{\circ}$ and Z = 4. A total of 1717 observed reflections were collected by the Weissenberg method with $CuK{\alpha}$ radiation. Structure was solved by heavy atom method and refined by block-diagonal least-squares methods to the R value of 0.14. The conformational angle formed by the S-C(l) bond with that of N(2)-C(7), when the projection in taken along the S-N(2), is $73^{\circ}.$ The benzene ring is planar and makes an angle of $60^{\circ}$ with the plane of the isoxazole ring, which is also planar. The sodium atom has a distorted octahedral coordination of N(l) and five oxygen atoms from hydrate molecules. Sodium sulfisoxazole hexahydrate shows fourteen different hydrogen bondings in the crystal. These are six $O-H{\cdots}O-H bonds, three $O-H{\cdots}O$ bonds, two $O-N{\cdots}N,$ one $N-H{\cdots}O,O-H{\cdots}N,N-H{\cdots}O-H$ bond, with the distances in the range of 2.71 to $3.04{\AA}.$.

• Bulletin of the Korean Chemical Society
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• v.31 no.5
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• pp.1283-1288
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• 2010

A novel polyaminopolycarboxylate ligand with many coordination sites, N,N,$N^1,N^1,N^2,N^2$-[( 2,4,6-tri(aminomethyl)-pyridine]hexakis(acetic acid) (TPHA), was designed and synthesized and its lanthanide complexes $Na_6Tb_2$(TPHA)$Cl_6{\cdot}14H_2O$, $Na_6Eu_2$(TPHA)$Cl_6{\cdot}8H_2O$, $Na_6Gd_2$(TPHA)$Cl_6{\cdot}11H_2O$ and $Na_6Sm_2$(TPHA)$Cl_6{\cdot}9H_2O$ were successfully prepared. The ligand and the complexes were characterized by elemental analysis, IR, mass, NMR and TG-DTA. The TG-DTA studies indicated that the complexes had a high thermal stability, whose initial decomposition temperature was over $270^{\circ}C$. The luminescence properties of the complexes in solid state were investigated and the results suggested that $Tb^{3+}$ and $Eu^{3+}$ ions could be sensitized efficiently by the ligand, especially the Tb(III) complex displayed a very strong luminescence intensity (> 10000) and only displayed characteristic metal-centered luminescence. Also, the correlative comparison between the structure of ligand and luminescence properties showed how the number of the coordination atoms of ligand can be a prominent factor in the effectiveness of ligand-to-metal energy transfer.

• Bulletin of the Korean Chemical Society
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• v.33 no.9
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• pp.2917-2924
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• 2012

Four novel metal-organic complexes $[Cd_2(IP)_2(TBZ)_2(H_2O)_2]{\cdot}(H_2O)$ (1), $[Zn_4(IP)_4(TBZ)_4]{\cdot}2(H_2O)$ (2), $[Zn_2(BTC)(TBZ)_2(CO_2H)]$ (3), [Co(PDC)(TBZ)] (4) (where IP = isophthalate; TBZ = thiabendazole; BTC = 1,3,5-benzenetricarboxylate; PDC = pyridine-3,4-dicarboxylate) have been prepared and characterized by IR spectrum, elemental analysis, thermogravimetric analysis, and single-crystal X-ray diffraction. X-ray structure analysis reveals that 1, 2, and 3 are one-dimensional chain polymers, while 4 is a two-dimensional network polymer. The TBZ acts as a typical chelating ligand coordinated to the metal center in all complexes. The 1D chain architecture of 1 is constructed from isophthalates and cadmium atoms. A simultaneous presence of chelating, monodentate and bidentate coordination modes of IP ligands is observed in complex 2. In complex 3, the 16-membered rings are alternately arranged forming an infinite 1D double-chain structure. The 2D skeleton of 4 is formed by cobalt ions as nodes and PDC dianions as spacers, through coordination bonds. The hydrogen bonds and ${\pi}-{\pi}$ stacking play important roles in affecting the final structure where complexes 1 and 3 have 2D supramolecular networks, while complexes 2 and 4 have 3D supramolecular architectures.

• Journal of the Korean Society for Heat Treatment
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• v.20 no.6
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• pp.323-328
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• 2007

This study has been investigated the effect of high temperature gas nitriding (HTGN) heat treatment of STS 444 (18Cr-0.01Ni-0.01C-0.2Nb) ferritic stainless steel in an atmosphere of nitrogen gas at the temperature range between $1050^{\circ}C\;and\;1150^{\circ}C$. The surface layer was changed into martensite and austenite with the nitrides of NbCrN by HTGN treatment. Due to the precipitation of nitrides and matrensite formation, the hardness of the surface layer showed $400Hv{\sim}530Hv$. The nitrogen concentration of the surface layer appeared as 0.05%, 0.12% and 0.92%, respectively, at $1050^{\circ}C,\;1100^{\circ}C\;and\;1150^{\circ}C$. When the nitrogen is permeated from surface to interior, Nb and Cr, which have strong affinities with nitrogen, also move from interior to surface. Therefore it is considered that this counter-current of atoms promotes the formation of NbCrN at the surface layer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.414-414
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• 2008

Vertically well-aligned Ga-doped ZnO nanorods with different Ga contents were grown by thermal evaporation on a ZnO template. The Ga-doped ZnO nanorods synthesized with 50 wt % Ga with respect to the Zn content showed maximum compressive stress relative to the ZnO template, which led to a rapid growth rate along the c-axis due to the rapid release of stored strain energy. A further increase in the Ga content improved the conductivity of the nanorods due to the substitutional incorporation of Ga atoms in the Zn sites based on a decrease in lattice spacing. The p-n diode structure with Ga-doped ZnO nanorods, as a n-type, displayed a distinct white light luminescence from the side-view of the device, showing weak ultraviolet and various deep-level emissions.

• Journal of Environmental Science International
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• v.5 no.2
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• pp.211-220
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• 1996

New thin-and diselena-crown ethers containing two suffer and selenium donor atoms have been prepared. And then, mercury ($Hg^{2+}$) ion-selective electrodes with PVC-plasticizer (STPB) based on some macrocycles as neutral carriers were also made. The electrochemical selectivities for various ions, and the effects for macrocycles, matrix of membranes, ratio of plasticizer to macrowcles, concentration and pH of test solution were investigated on the $Hg^{2+}$ ion-selective electrodes. The 1, 10-diselena-18-crown-6-PVC-STPB (sodium tetraphenylborate) exhibited good linear responses of ${28.2}\pm{0.6}$ decade-1 for $Hg^{2+}$ ion in the conientration ranges of $10^{-2}~10^{-6}$ M $Hg^{2+}$ ion. This electrode exhibited comparatively good selectivities for $Hg^{2+}$ ion in comparison with alkali and alkaline earth metal ions, some heavy metal ions and rare earth metal ion in the range of pH 2.5~6.0. In addition, this electrode was applied as a sensor in the titration of $Hg^{2+}$ ion with $1^-$ ion in water.

• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2271-2276
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• 2014

Second-order rate constants ($k_N$) have been measured spectrophotometrically for the reaction of 4-chloro-2-nitrophenyl X-substituted-benzoates (6a-6h) with a series of primary amines including hydrazine in 80 mol % $H_2O$/20 mol % DMSO at $25.0^{\circ}C$. The Br${\o}$nsted-type plot for the reaction of 4-chloro-2-nitrophenyl benzoate (6d) is linear with ${\beta}_{nuc}$ = 0.74 when hydrazine is excluded from the correlation. Such a linear Br${\o}$nsted-type plot is typical for reactions reported previously to proceed through a stepwise mechanism in which expulsion of the leaving group occurs in the rate-determining step (RDS). The Hammett plots for the reactions of 6a-6h with hydrazine and glycylglycine are nonlinear. In contrast, the Yukawa-Tsuno plots exhibit excellent linear correlations with ${\rho}_X$ = 1.29-1.45 and r = 0.53-0.56, indicating that the nonlinear Hammett plots are not due to a change in RDS but are caused by resonance stabilization of the substrates possessing an electron-donating group (EDG). Hydrazine is ca. 47-93 times more reactive than similarly basic glycylglycine toward 6a-6h (e.g., the ${\alpha}$-effect). The ${\alpha}$-effect increases as the substituent X in the benzoyl moiety becomes a stronger electron-withdrawing group (EWG), indicating that destabilization of the ground state (GS) of hydrazine through the repulsion between the nonbonding electron pairs on the two N atoms is not solely responsible for the substituent-dependent ${\alpha}$-effect. Stabilization of transition state (TS) through five-membered cyclic TSs, which would increase the electrophilicity of the reaction center or the nucleofugality of the leaving group, contributes to the ${\alpha}$-effect observed in this study.

• Journal of the Korean Chemical Society
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• v.51 no.1
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• pp.31-35
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• 2007

The tripodal copper(II) complex [Cu(pmea)(H2O)](ClO4)2·H2O (1) (pmea = bis[(2-pyridyl)methyl]-2-(2-pyridyl)ethylamine) has been synthesized and structurally characterized by X-ray diffraction method. It crystallizes in the triclinic system P-1 with a = 9.9362(9), b = 15.7299(17), c = 18.0562(11) A, α = 68.760(8), β = 76.331(6), γ = 77.092(9)°, V = 2526.2(4) A3, Z = 2. Each copper atom reveals a distorted square pyramidal with three nitrogen atoms of the pmea ligand and water molecule occupying the basal plane and one nitrogen atom from the pyridine ring according the axial position. The cyclic voltammogram of 1 undergoes reversible one-electron oxidation to the CuIII and reversible one-electron reduction to the CuI.

• Bulletin of the Korean Chemical Society
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• v.27 no.11
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• pp.1747-1751
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• 2006

The dinuclear tetraazadiphenol macrocyclic nickel(II) complexes [$Ni_2$([20]-DCHDC)]$Cl_2$ (I), [$Ni_2$([20]-DCHDC)]$(ClO_4)_2{\cdot}2CH_3CN $ (II(b)) and [$Ni_2$([20]-DCHDC)$(NCS)_2$] (III) {$H_2$[20]-DCHDC = 14,29-dimethyl-3,10,18,25-tetraazapentacyclo-[25,3,1,$0^{4,9}$,$1^{12,16}$,$0^{19,24}$]ditriacontane-2,10,12,14,16(32),17,27(31), 28,30-decane-31,32-diol} have been synthesized by self-assembly and characterized by elemental analyses, conductances, FT-IR and FAB-MS spectra, and single crystal X-ray diffraction. The crystal structure of II(b) is determined. It crystallizes in the monoclinic space group P2(1)/c. The coordination geometries around Ni(II) ions in I and II(b) are identical and square planes. In complex III each Ni(II) ion is coordinated to $N_2O_2$ plane from the macrocycle and N atoms of NCS- ions occupying the axial positions, forming a square pyramidal geometry. The nonbonded Ni…Ni intermetallic separation in the complex II(b) is 2.8078(10) $\AA$. The FAB mass spectra of I, II and III display major fragments at m/z 635.1, 699.4 and 662.4 corresponding to [$Ni_2$([20]-DCHDC)(Cl + 2H)]$^+$, [$Ni_2$([20]-DCHDC)$(ClO_4\;+\;2H)]^+$ and [$Ni_2$([20]-DCHDC)(NCS) + 6H]$^+$, respectively.