• Bulletin of the Korean Chemical Society
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• v.11 no.5
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• pp.379-383
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• 1990

$YBa_2Cu_{3-x}Ni_xO_{7-{\delta}}$, with x = 0.05, 0.2, 0.4, 0.7 and 1.0 had been prepared by the thermal decomposition of corresponding nitrates. Among them, the sample with x = 0.05 shows above-liquid-$N_2$ temperature superconductivity with $T_c$ of 88.7K. According to the X-ray diffraction analysis, its crystal symmetry was estimated as orthorhombic with the lattice parameters of a = 3.866${\AA}$, b = 3.893${\AA}$, c = 11.715${\AA}$. The chemical composition of the sample was determined by electron probe microanalysis and the chemical composition around its grain boundaries was carefully studied by the X-ray line scanning technique. From the observed binding energy of Ni-$2p_{3/2}$ orbital electron (B.E. = 853 eV) measured by X-ray photoelectron spectroscopy, the valency state of nickel stabilized in $YBa_2Cu_{2.95}Ni_{0.05}O_{7-{\delta}}$ oxide lattice could be determined to be Ni(II).

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.1
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• pp.1-8
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• 2017

Catalytic synthesis and properties of ${\beta}-Ga_2O_3$ nanowires grown by metal organic chemical vapor deposition are reported. Au, Ni and Cu catalysts were suitable for the growth of $Ga_2O_3$ nanowires under our experimental conditions. The $Ga_2O_3$ nanowires grown by using Au, Ni and Cu catalysts showed different growth rates and morphologies in each case. We found the $Ga_2O_3$ nanowires were grown by the Vapor-Solid (VS) process when Ni was used as a catalyst while the Vapor-Liquid-Solid (VLS) was a dominant process in case of Au and Cu catalysts. Also, we found nanowires showed different optical properties depend on catalytic metals. On the other hand, for the cases of Ti, Sn and Ag catalysts, nanowires could not be obtained under the same condition of Au, Cu and Ni catalytic synthesis. We found that these results are related to the different characteristics of each catalyst, such as, melting points and phase diagrams with gallium metal.

• Journal of the Korean Chemical Society
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• v.27 no.2
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• pp.83-94
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• 1983

The effects of cis and trans configurations of ligands for $[M(II)O_3N_3]$ and $[Ni(II) O_2N_4]$ type complexes [M(II) = Co(III), Ni(II) and Cu(II)] on the calculated dipole moments have been investigated, adpoting the eigenvectors of EHT calculation. The calculated dipole moments for cis complexes are higher than those of trans complexes. The calculated dipole moments for the octahedral trans $[Co(III)O_3N_3]$ type complex fall in the range of experimental values. However the calculated dipole moments for cis $[Ni(II) O_2N_4]$ type complexes fall in the range of the experimental values. These results predicts the trans structure for $[Co(III)O_3N_3]$ and $[Ni(II) O_2N_4]$ type complexes. Those structures are in agreement with the experimental one (Three bidentate (O-N) ligands in $[M(II)O_3N_3]$ type complexes coordinate to the metal ion and two tridentate (O-N-N) ligands in [Ni(II)O2N4] type complexes coordinate to Ni(II) ion).

• Journal of the Korean Magnetics Society
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• v.20 no.5
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• pp.182-186
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• 2010

Effect of cobalt substitution on the sintering behavior and magnetic properties of a NiZnCu ferrite was studied. $Ni_{0.36-x}Co_xZn_{0.44}Cu_{0.22}Fe_{1.98}O_4(0{\leq}x{\leq}0.04)$ ferrite was fabricated by a solid stat reaction method. It was proposed and experimentally verified that $Co^{2+}$ substituted NiZnCu ferrite was effective on improving the quality factor and magnetic properties of NiZnCu ferrites for multilayer chip inductors. The ferrite was sintered without sintering aids, at $880{\sim}920^{\circ}C$, for 2 h and the initial permeability, quality factor, density, shrinkage, saturation magnetization, and coercivity were also measured. The quality factor (Q) was increased linearly up to x = 0.01 and decreased rapidly over x = 0.01. As the cobalt content increased, the initial permeability and density of the ferrites decreases. The initial permeability of toroidal sample for $Ni_{0.35}Co_{0.01}Zn_{0.44}Cu_{0.22}Fe_{1.98}O_4$ ferrites sintered at $900^{\circ}C$ was 130 at 1 MHz and quality factor was 230.

• Journal of the Korean Chemical Society
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• v.30 no.6
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• pp.526-531
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• 1986

The stability constants of 1,15-diaza-3,4:12,13-dibenzo-5,8,11-trioxacycloheptadecane (NenOdien H$_4$, L) with transition metal ions such as $Co^{2+},\;Ni^{2+},\;Cu^{2+},\;and\;Zn^{2+}$ have been determined by potentiometry in 95% methanol solution at 25$^{\circ}$C. The complex formation of the NenOdien $_4$ with the transition metal ions depends on the basicity of the donor atoms. The order of complex stability was Co(II) < Ni(II) < Cu(II) > Zn(II). The geometries of the complexes in solid state were discussed by visible-near infrared and infrared spectrophotometry, elemental analysis and electro-conductivity. The results suggest that the geometries of the solid complexes are octahedral for $[CoL_2(OH_2)Cl]Cl{\cdot}2H_2O$, $[NiL_2(OH_2)Cl]Cl{\cdot}2H_2O$, and $[ZnLCl_2]{\cdot}\frac{1}{2}H_2O$ and square pyramidal for [CuLCl]Cl, respectively.

• Journal of Sensor Science and Technology
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• v.17 no.4
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• pp.303-307
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• 2008

$NiO,\;Cu_2O,\;Mn_2O_3$ and $Cr_2O_3$ as p-type semiconductors were added in CoO with 15 wt.% ethylene glycol binder and measured the butane gas sensing characteristics. The highest sensitivity is obtained for the NiO-CoO sensors. CoO-20 at.% NiO sensor with 15 wt.% ethylene glycol binder sintered at $1100^{\circ}C$ for 24 h exhibits high sensitivity of 90 % to 5000 ppm butane gas at the sensor temperature of $250^{\circ}C$, compared to low sensitivities at the low operating temperature for commercial sensors. Response and recovery times are, respectively, within few seconds and 1min in the static flow system, indicating rapid adsorption and desorption of butane gas on sensor surface even at this low temperature.

• Clean Technology
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• v.13 no.4
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• pp.287-292
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• 2007

[ $M/Al_2O_3$ ] (M = Mn, Fe, Co, Ni, Cu) catalysts supported on commercial alumina ($Al_2O_3$) were prepared by an impregnation method, and were applied to the hydrogen production by auto-thermal reforming of ethanol. It was revealed that each catalyst retained its own metallic phase and product distribution strongly depended on the identity of active metal. Among the catalysts prepared, $Ni/Al_2O_3$ and $Co/Al_2O_3$ showed the best catalytic performance in the auto-thermal reforming of ethanol. However, the reaction mechanisms over these two catalysts were different. Ni/Al_2O_3 catalyst showed 100% ethanol conversion at $500^{\circ}C$, but it exhibited a rapid decrease in hydrogen selectivity. Although $Co/Al_2O_3$ catalyst showed an excellent performance in hydrogen selectivity, on the other hand, no significant improvement in hydrogen yield was observed due to the low ethanol conversion over the catalyst.

• Bulletin of the Korean Chemical Society
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• v.29 no.10
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• pp.1905-1910
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• 2008

The reaction of 3,14-dimethyl-2,6,13,17-tetraazatetracyclo[16.4.0$0^{1.18}.0^{7.12}$]docosane ($L^1$) with formaldehyde in warm methanol yielded 3,14-dimethyl-2,6,13,17-tetraazatetracyclo[16.4.$1^{2.6}.0^{1.18}.0^{7.12}$]tricosane ($L^7$) containing one 1,3-diazacyclohexane subunit. In methanol, $L^7$ readily reacts with $Cu^{2+}$ ion to form [$CuL^7(H_2O)$]$^{2+}$ which is extremely inert against methanolysis. In the solution containing $Ni^{2+}$ ion, however, $L^7$ reacts with methanol to yield [$NiL^3$]$^{2+}$ ($L^3$ = 2-(methoxymethyl)-5,16-dimethyl-2,6,13,17-tetraazatricyclo[16.4.$0^{1.18}.0^{7.12}$]- docosane), in which one N-$CH_2OCH_3$ pendant arm is appended. The copper(II) complex [$CuL^7(H_2O)$]- $(ClO_4)_2{\cdot}3H_2O\;(I{\cdot}3H_2O)$ has a severely distorted trigonal bipyramidal coordination geometry with a 4-5- 6-5 chelate ring sequence. The crystal structure of [$NiL^3$]$(PF_6)_2{\cdot}2H_2O$ (IIb) shows that the N-$CH_2OCH_3$ pendant arm is not coordinated to the metal ion in the solid state. In various solvents (S), however, the nickel(II) complex exists as a mixture of [$NiL^3$(S)]$^{2+}$, in which the N-$CH_2OCH_3$ group as well as S is coordinated to the metal ion, and [$NiL^3$]^{2+}.

• Journal of the Korean Magnetics Society
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• v.17 no.6
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• pp.238-241
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• 2007

Ni-Cu-Zn ferrites were prepared by the co-precipitation. Physical properties and Microwave absorbing properties were investigated in Ni-Cu-Zn ferrite for the aim of microwave absorbers. From the analysis of X-ray diffraction patterns, we can see that all the particles have only a single phase spinel structure. The loss factor was maximum at sintering temperature $1100^{\circ}C$. The initial permeability of sintered ferrite obtained was an average of 50. We found that the $(Ni_{0.7}Cu_{0.2}Zn_{0.1}O)_{1.02}(Fe_2O_3)_{0.98}$ can be used in ferrite rubber composite microwave absorber when sintering temperature at $1100^{\circ}C$.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.11a
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• pp.92-97
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• 2001

This paper was studied on the effect of temperature on corrosion of absorption refrigeration systems using LiBr-$H_2O$ working fluids. In the fresh water and 62 %lithium bromide solution at $70^{\circ}C$, polarization test of SS 400, Cu(Cl220T-OL) and Ni-Al bronze was carried out. And Polarization behavior, polarization resistance characteristics, corrosion rate(mmpy) and corrosion sensitivity of materials forming absorption refrigeration systems was considered. The main results are as following: As the experimental temperature increase, the change of corrosion rate of Ni-Al bronze become duller than SS 400 and Cu in 62 % lithium bromide solution. Open circuit potential of SS 400 is less noble than that of Cu and Ni-Al bronze in fresh water, but that becomes noble than Cu and Ni-Al bronze in 62 % lithium bromide solution. The corrosion sensitivity of Ni-Al bronze was controlled than that of Cu and SS 400 in 62% LiBr solution.