• Journal of the Korean Ceramic Society
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• v.33 no.8
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• pp.895-900
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• 1996

Ba(Ti1-xSnx)4O9 powder was synthesized by oxalate method. With the substitution of Sn into Ti site the sintered BaTiO4 crystal phase was stabilized due to the formation of solid solution. The optimal amounts of Sn solutbility for formation of BaTi4O9 crystalline phase was 0.16mole and of Sn was substituted and sintering was done at 135$0^{\circ}C$ for 30 minutes long rod type crystal was well developed and the highest Q value was obtained. But dielectric constant wasnearly constant without regarding to the Sn addition and the sintering time.

• Korean Journal of Materials Research
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• v.24 no.1
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• pp.43-47
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• 2014

NiO-doped hibonite pigments were synthesized by the solid state method to get stabilized blue color pigment in both oxidation and reduction atmospheres. Optimum substitution condition with NiO for hibonite blue pigment was investigated. Experimental results were comparable to those of previous cobalt-minimization studies performed with other phosphate- or oxide-based cobalt-containing ceramic pigments (having olivine ($Co_2SiO_4$), spinel ($CoAl_2O_4$), or with co-doped willemite ($(Co,Zn)_2SiO_4$) structures). Composition was designed varying the NiO molar ratio increasing with $SnO_2$. The optimum substitution content is 0.93 mole NiO with 0.75mole $SnO_2$. The characteristics of the synthesized pigment were analyzed by XRD, Raman spectroscopy, SEM, and UV-vis. Synthesized pigment was applied to a lime-barium glaze with 10 wt% each and fired at an oxidation atmosphere of $1250^{\circ}C/1h$ and a reducing atmosphere $1240^{\circ}C/1h$. Blue color was obtained with $L^*a^*b^*$ values at 43.39, -6.78, -18.20 under a reducing atmosphere and 41.66, -6.36, -14.7 under and oxidation atmosphere, respectively.

• Bulletin of the Korean Chemical Society
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• v.18 no.7
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• pp.743-749
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• 1997

Local structure refinement of the BaFe1-xSnxO3-y system (x=0.00-0.50) has been carried out with Fe K-edge x-ray absorpion spectroscopic studies. It is found out that the Fe ions are placed in two different symmetric sites such as tetrahedral and octahedral sites in the compounds by comparison with Fe K-edge x-ray absorption near edge structure (XANES) spectrum of the γ-Fe2O3 compound as a reference. Small absorption peaks of dipole-forbiden transitions appear at a pre-edge region of 7111 eV due to the existence of Fe ions in the tetrahedral and octahedral sites. The peak intensity decreases with the substitution amount of Sn ion. Three different absorption peaks of 1s→4p dipole-allowed transition appear on the energy region between 7123 and 7131 eV. The peaks correspond to 1s→4p main transition of Fe ions in tetrahedral and octahedral sites and 1s→4p transition followed by the shakedown process of ligand to metal charge transfer. The bond distances between Fe ions in the tetrahedral site and nearest neighboring oxygen atom (Fe-4O), and those in octahedral site (Fe-6O) are determined with the extended x-ray absorption fine structure (EXAFS) analysis. Two different interatomic distances increase with the substitution amount of Sn ion and also the bond lengths of Fe-4O are shorter than those of Fe-6O in all compounds.

• Journal of the Korean Ceramic Society
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• v.45 no.8
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• pp.459-463
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• 2008

$P_2O_5-SnO_2$ system $0.5SnO_2-xP_2O_5-(0.5-x)B_2O_3$(x=0.1, 0.2, 0.3, 0.4, 0.5) glasses have been prepared for Pb-free low temperature glass frit. A investigation about the effect of $B_2O_3$ substitution on properties of $P_2O_5$ glasses, including glass structure properties, thermal properties, and mechanical properties was presented. Substance that is responsible for in moisture absorption existing circumstances supposes by phosphate, and excess moisture tolerance that state funeral's structure is improved breaking does not affect in state funeral bond that only most single bond remains, and can know that does not suffer big impact in boric oxide anomaly present state. This phenomenon estimates that connect with structure change. It is thought according to link this result the phosphoric acid happened structural change. $B_2O_3$ displacement quantity 0.3 mole put out $BO_4$ structures, but above 0.3 mole it changed with the case $BO_3$ structure which it displaces.

• Bulletin of the Korean Chemical Society
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• v.19 no.12
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• pp.1334-1336
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• 1998

Kinetic studies are carried out on the reactions of 2-chloro-2-propen-1-yl arenesulfonates with anilines and N,N-dimethylanilines in acetonitrilile at 45.0 ℃. The 2-chloro substituent is found to deactive the allyl moiety with considerable decrease in the rates. The sign and magnitude of the cross-interaction constant (ρxz 0.3) and the inverse secondary kinetic isotope effect (kH/kD 0.92) support an SN2 mechanism with a relatively tight transition state. The possibility of an SN2' mechanism can be safely precluded based on the ρxz values observed.

• 한국초전도학회:학술대회논문집
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• v.14
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• pp.38-38
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• 2004

• Korean Journal of Materials Research
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• v.20 no.2
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• pp.65-71
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• 2010

In this study, the effect of Sn and Mg on microstructure and mechanical properties of Cu-Fe-P alloy were investigated by using scanning electron microscope, transmission electron microscope, tensile strength, electrical conductivity, thermal softening, size and distribution of the precipitation phases in order to satisfy characteristic for lead frame material. It was observed that Cu-0.14wt%Fe-0.03wt%P-0.05wt%Si-0.1wt%Zn with Sn and Mg indicates increasing tensile strength compare with PMC90 since Sn restrained the growth of the Fe-P precipitation phase on the matrix. However, the electrical conductivity was decreased by adding addition of Sn and Mg because Sn was dispersed on the matrix and restrained the growth of the Fe-P precipitation. The size of 100 nm $Mg_3P_2$ precipitation phase was observed having lattice parameter $a:12.01{\AA}$ such that [111] zone axis. According to the results of the study, the tensile strength and the electrical conductivity satisfied the requirements of lead frame; so, there is the possibility of application as a substitution material for lead frame of Cu alloy.

• Bulletin of the Korean Chemical Society
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• v.18 no.9
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• pp.1010-1013
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• 1997

Nucleophilic substitution reactions of (Z)-phenylethyl (X)-benzenesulfonates with (Y)-pyridines were investigated in acetonitrile at 60 ℃ under respective pressures. The magnitudes of the Hammett reaction constants, ρX, ρY and ρZ indicate that a stronger nucleophile leads to a greater degree of bond formation of C-N and a better leaving group is accompanied by a less degree of bond breaking. The magnitude of correlation interaction term, ρij can be used to determine the structure of the transition state (TS) for the SN reaction. As the pressure is increased, the Hammett reaction constants, ρX and |ρY|, are decreased, but correlation interaction coefficient, ρXZ and |ρYZ|, are increased. The results indicate that the reaction of (Z)-phenylethyl (X)-benzenesulfonates with (Y)-pyridines probably moves from a dissociative SN2 to early-type concerted SN2 mechanism by increasing pressure. This result shows that the correlation interaction term ρij can be useful tool to determine the structure of TS, and also the sign of the product ρXZ·ρYZ can be predict the movement of the TS.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.2 s.344
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• pp.13-17
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• 2006

Pentacene channel for organic thin film transistor was deposited on the SiOC film by thermal evaporation. The growth of pentacene is related with the Diels-Alder reaction and the nucleophilic reaction by the thermal induction. The surface is an important factor to control the recursive Diels-Alder reaction for growing of pentacene on SiOC far The terminal C=C double bond of pentacene molecule was broken easily as a result of attack of the nucleophilic reagents on the surface of SiOC film. The nucleophilic reaction can be accelerated by increasing temperature on surface, and it maks pentacene to grow hardly on the SiOC film with a flow rate ratio of $O_2/(BTMSM+O_2)=0.5$ due to its inorganic property. The nucleophlic reaction mechanism is $SN_2(bimolecular nucleophilic substitution)$ type.

• Textile Coloration and Finishing
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• v.19 no.4
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• pp.18-25
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• 2007

Kinetics and mechanism for alkaline hydrolysis of C. I. Disperse Green 9(G-9) of dinitrothiophene disperse dye were investigated. As soon as G-9 contacted with alkali, instant and continuous decreases of color strength of G-9 followed with increasing time. The hydrolysis rate of G-9 increased with increasing alkali, and it was found that alkali appeared first order dependence. The observed rate constants obtained from hydrolysis of various amount of dye were similar values, and calculation of initial rates showed that G-9 hydrolyzed by first order reaction for dye. Therefore it was confirmed that the overall reaction was second order, $SN_2$ of nucleophilic substitution reaction. Increasing temperature enhanced the hydrolysis of G-9. From the results of hydrolysis performed at various temperatures, it was obtained that activation energy(Ea) was 12.6 kcal/mole, enthalpy of reaction(${\triangle}H$) was 12.0 kcal/mole, and entropy of reaction(${\triangle}S$) was $29.8J/mol{\cdot}K$.