• Korean Journal of Materials Research
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• v.4 no.2
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• pp.233-240
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• 1994

We have investigated how the magneto-optical and recording properties of Pt/Co modulated films vary with sample preparation conditions : sputtering at various gas pressures, sputtering with Xe instead of Ar, and etching the buffer layers, etc. The magneto-optical characteristics of Pt/Co multilayers was comparable with those of currently prevailing rare-earth transition-metal alloys(Tb-Fe-Co amorphous films). On a disk of $12{\times}[Pt10.7\;{\AA}/Co2.8{\;}{\AA}]$ multilayer enhanced with 70nm silicon nitride, we have achieved a CNR of 36dB with a reading laser(${\lambda}\;=\;780nm$) power of 2.5-4.5mW for 720KHz carrier at 1.4m/s and the enhanced kerr rotation angle of $1.23^{\circ}$ at 780nm. It is suggested that Pt/Co modulated films clearly are very promising magneto-optical materials for a commercially use.

• Bulletin of the Korean Chemical Society
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• v.24 no.11
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• pp.1585-1589
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• 2003

A PVC-based membrane electrode for thallium(I) ions based on 1,21,23,25-tetramethyl-2,20: 3,19-dimetheno-[H, 2] H, 23H, 25H-bis-[1,3] dioxocino[5,4-i:5',4'-i] benzo [1,2-d: 5.4-d'] bis [1,3] benzodioxocin(II) has been prepared. The electrode displays a linear dynamic range of $1.0{\times}10^{-1}-1.0{\times}10^{-5}$ M, with a Nernstian slope of $59.8{\pm}0.2\;mV\;{decad^-1}$, and a detection limit $5.0{\times}10^{-6}$ M. It has a very fast response time of<10 s and can be used for at least ten weeks without a considerable divergence in potentials. This electrode revealed comparatively good selectivity with respect to alkali, alkaline earth, and some transition and heavy metal ions and was effective in a pH range of 2.0-10.0. It was used as an indicator electrode in potentiometric titration of thallium ion with sulfide ion.

• Journal of the Korean Chemical Society
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• v.23 no.4
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• pp.198-205
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• 1979

A valence bond method of calculation of the dipole moments for octahedral $(M(III)0_3S_3)$ type complexes are developed, using $d^2sp^3 $hybrid orbitals of the central metal ions and the single basis set orbital of ligands. (M (III) =V (III), Cr (III), Mn (III), Fe (III), Co (III), Ru (III), Rh (III) and OS (III)). In this method the mixing coefficient of the valence basis sets for the central metal ion with the appropriate ligand orbitals is not required to be the same, differently from the molecular orbital method. The valence bond method is much more easier to calculate the dipole moments for octahedral complexes than the approximate molecular orbital method and the calculated results are also in the range of the experimental vaues.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.4 no.2
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• pp.133-142
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• 1984

With the weld-joined compact tension specimens compared with each other, that is, transverse and lengthwise about the crack propagation direction, high and low in the input heat level, same as and lower than the base metal in the strength of weld material, the fatigue test were performed. With these data, the log-log curves between the fatigue crack propagation rate ${\frac{da}{dN}}$ and the transition range of the stress intensity factor ${\Delta}K$ ahead the crack tip were drawed. These curves were compared and estimated among each compared specimens, among each zones, that is, the base metal, the heat-affected metal and the weld-mixed metal, and between this study and the past studies. Basically, Little difference in the slope of the $da/dN-{\Delta}K$ relation was showed in all the welded directions, all the input heat levels and all the zones. But, First, to comparison with in the past studies about the base metals, it was showed that da/dN started in the much later rate, increased faster and stoped in the little faster rate. Second, it was showed that, near the time the crack's going from the heat-affected zone to the weld-mixed metal da/dN decreased a little for a while. Third, in the lengthwise weld compared with the transverse weld, in the high input heat weld compared with the low input heat weld in the case used the weld material of the same strength as the base metal, in the opposite case in the case used the one of the lower strength than the base metal, in the case used the weld material of the same strength as compared with the lower strength than the base metal beside the high input heat and the lengthwise weld, it was showed that the crack occured earlier in lower ${\Delta}K$ and later da/dN, the curves went with the same slope. Forth, in the lengthwise weld compared with the transverse weld in the low input heat weld, in the low input heat weld compared with the high input heat weld, it was showed that da/dN went with the lower level.

• Proceedings of the Korean Magnestics Society Conference
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• 2003.06a
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• pp.21-21
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• 2003

Microstructure and magnetic transport phenomina in rf sputtered AlN/Co type ten-layered discontinuous films of nanoscaled [AlN (3 nm)/Co (t nm)]...$\sub$10/ with t$\sub$Co/=1.0∼2.0 nm have been investigated. The microstructure and tunneling magnetic resistance of the samples are strongly dependent on the thickness of Co layer. Negative tunneling magneto-resistance due to the spin-dependent transport has been observed along the current-in-plane configuration in the samples having the Co layers below 1.6 nm thick. When the thickness of Co layer was less than 1,2 nm, randomly oriented granular Co particles were completely isolated and embedded in amorphous AlN matrix, and the films showed the superparamagnetic behavior with a high MR value of Δ$\rho$/$\rho$$\sub$0/=1.8 %. As t$\sub$Co/ increases, a transition from the regime of co-existence of superparamagnetic and ferromagnetic behaviors to ferromagnetic behavior was observed. Tunneling barrier called "decay length for tunneling" for the films having the thickness of Co layer from 1.4 to 1.6 nm was measured to be ranged from 0.004 to 0.021 ${\AA}$$\^$-1/.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1692-1696
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• 2011

The reactions of 1H-1,2,4-triazole (Htr) with $MX_2$ ($ZnCl_2$ for 1; $CdBr_2$ for 2) resulted in two coordination polymers, [Zn(tr)Cl]$_n$ (1) and $[Cd(Htr)_2Br_2]_n$ (2). The structural analyses indicate that 1 and 2 feature a 2D layer and 1D triple chain, respectively. In 1, neighouring Zn atoms are connected by ${\mu}_3-1$ ${\kappa}N$: 2 ${\kappa}N$: $4{\kappa}N-tr^-$ anionic ligand into 6- and 16-membered rings, further grow into a 2D sheet. Cd atoms in 2 are bonded by two ${\mu}_2-Br^-$ bridges and neutral ${\mu}_2$-1 ${\kappa}N$: 2 ${\kappa}N$-Htr to form a 1D triple chain. The fluorescent characterizations of 1, 2 and the free Htr ligand feature simlilar emission peakes at 444, 446 and 423 nm respectively, which can be assigned to intra-ligand ${\pi}-{\pi}^*$ transition of (H)tr. The energy gaps of 5.90 eV for 1, 5.16 eV for 2, and 5.93 eV for Htr suggest that the compounds behave as insulators.

• Carbon letters
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• v.7 no.4
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• pp.245-248
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• 2006

Thin films of carbon-nano materials (CNMs) of different morphology have been successfully deposited on ceramic substrate by CVD at temperatures $800^{\circ}C$, $850^{\circ}C$ and $900^{\circ}C$ using plant based oils in the presence of transition metal catalysts (Ni, Co and Ni/Co alloys). Based on the return and insertion loss, microwave absorption properties of thin film of nanocarbon material are measured using passive micro-Strip line components. The result indicates that amongst CNMs synthesized from oil of natural precursors (mustered oil - Brassica napus, Karanja oil - Pongamia glabra, Cotton oil - Gossipium hirsuta and Neem oil - Azadirachta indica) carbon nano fibers obtained from neem's seed oil showed better microwave absorption (~20dB) in the range of 8.0 GHz to 17.90 GHz.

• Bulletin of the Korean Chemical Society
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• v.16 no.9
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• pp.870-873
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• 1995

A new ternary transition-metal selenide, Ta2Ni3Se8 has been synthesized from a eutectic halide flux. The structure of this phase has been characterized by single crystal X-ray diffraction techniques. The compound crystallizes in the orthorhombic system (D2h9-Pbam, a= 14.788(4) Å, b= 10.467(3) Å, c=3.4563(8) Å) with two formula units in the unit cell. This compound adopts the Nb2Pd3Se8 structure type. Hence, there are two chains of edge-sharing selenium trigonal prisms centered by tantalum atoms and these chains are interconnected through two kinds of nickel atoms. Nickel occupies both square planar and square pyramidal sites as does palladium in Nb2Pd3Se8. Electrical conductivity measurements indicate that this material is semiconducting.

• Journal of the Korean Chemical Society
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• v.39 no.8
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• pp.611-616
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• 1995

Oxovanadium(IV) complexes with salicylaldoxime, o-vanilline oxime, 2-hydroxy-4-methoxybenzaldoxime, 2-hydroxy-5-methoxybenzaldoxime and 2-hydroxy-5-nitrobenzaldoxime were synthesized. The complexes have been characterized by elemental analysis, electric conductivity measurement, infrared spectrometry, electronic spectrometry, mass spectrometry, and thermal analysis. The results of elemental analysis were well coincided with the theoretical values. The values of molar conductance of the complexes in DMF implicated that the complexes were non-electrolyte. The characteristic stretching frequency of V=O appeared strong band in the range of $980{\pm}20\;cm^{-1}.$ All the complexes showed two d-d transition in visible spectra and two charge transfer transitions in ultraviolet spectra. Results of mass spectrometry of $VO(sal)_2\;and\;VO(van)_2$ indicated two peaks corresponding to vanadium containing ion(I) of 1 : 2(metal to ligand) chelate and a fragment ion(II) of 1 : 1 chelate due to loss of ligand radical from ion(I). The thermal analysis showed the endothermic peak due to the thermal decomposition.

• Journal of the Korean Chemical Society
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• v.34 no.1
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• pp.37-43
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• 1990

An effect of the spin-orbit coupling interaction of ligand orbitals and the intermixing │3d 〉and│4p > transition metal atomic orbitals on the ground state for a 3$d^9$ system in a strong crystal field of tetragonally distorted tetrahedral symmetry that belongs to the $D_{2d}$ point group has been investigated in this work, applying the degenerate perturbation theory. An LCAO-MO analysis in terms of the known energies of the d-d transitions for the tetragonally distorted $CuCl_4^{2-}$ ion in a single crystal of$Cs_2CuCl_4$shows that the covalent mixing of Cu 3d and ligand Cl 3p orbitals decreases dramatically with increasing Cu 4p contribution. The extent of effect on the energy level splitting for the ground state by the spin-orbit coupling interaction of ligand orbitals decreases significantly in orderTEX>$\Gamma_7(E)\;\to\;\Gamma_6(E)\; >\;\Gamma_7(B_2)\;\to\;\Gamma_6(E)\; >\;\Gamma_7(B_2)\;\to\;\Gamma_7(E)$.