• Journal of the Korean Chemical Society
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• v.7 no.1
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• pp.65-68
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• 1963

The solubility of ethyl bromide in nitrobenzene and in 1,2,4-trichlorobenzene has been measured at $19^{\circ}$ in the presence and absence of gallium bromide. When gallium bromide does not exist in the system, the solubility of ethyl bromide in nitrobenzene is greater than in 1,2,4-trichlorobenzene, indicating the stronger interaction of ethyl bromide with nitrobenzene than with 1,2,4-trichlorobenzene. When there exists gallium bromide in the system, an unstable 1: 1 complex, C2H5Br·GaBr3, of gallium bromide with ethyl bromide is formed in the solution. The 1: 1 complex in solution dissociates into the components to a large extent according to one of the following equilibria or both: $C_2H_5Br{\cdot}GaBr_3{\rightleftarrows}C_2H_5Br+GaBr_3$C_2H_5Br{\cdot}GaBr_3{\rightleftarrows}C_2H_5Br+1}2GaBr_3$$ The stability of the 1: 1 complex of ethyl bromide with gallium bromide is compared with that of the corresponding complex of methyl bromide.

• Bulletin of the Korean Chemical Society
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• v.26 no.1
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• pp.131-135
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• 2005

Gallium nitride (GaN) powders and nanowires were prepared by using tris(N,N-dimethyldithiocarbamato)gallium(III) (Ga(DmDTC)$_3$) and tris(N,N-diethyldithiocarbamato)gallium(III) (Ga(DeDTC)$_3$) as new precursors. The GaN powders were obtained by reaction of the complexes with ammonia in the temperature ranging from 500 to 1100 ${^{\circ}C}$. The process of conversion of the complexes to GaN was monitored by their weight loss, XRD, and $^{71}$Ga magic-angle spinning (MAS) NMR spectroscopy. Most likely the complexes decompose to $\gamma$ -Ga$_2$S$_3$ and then turn into GaN via amorphous gallium thionitrides (GaS$_x$N$_y$). The reactivity of Ga(DmDTC)$_3$ with ammonia was a little higher than that of Ga(DeDTC)$_3$. Room-temperature photoluminescence spectra of asprepared GaN powders exhibited the band-edge emission of GaN at 363 nm. GaN nanowires were obtained by nitridation of as-ground $\gamma$ -Ga$_2$S$_3$ powders to GaN powders, followed by sublimation without using templates or catalysts.

• Restorative Dentistry and Endodontics
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• v.22 no.2
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• pp.575-595
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• 1997

Replacement resorption is followed by the delayed replantation of an avulsed tooth. Currently no effective treatment is substantiated for replacement resorption. The purpose of this study was to investigate the effect of stannous fluoride, bisphosphonate (etidronate disodium) and gallium nitrate, which have been shown to reduce dentin resorption, on human dentin. Osteoclasts were collected from tibeas of chick embryo. The cells were well agitated to prevent adhesion and seeded onto the sliced human dentin wafers which had been soaked in either culture media (control), or several different concentrations of stannous fluoride, etidronate disodium (l-hydroxyethylidene -1,1-bisphosphonate disodium), and gallium nitrate. Resorption was measured by counting the number of resorptive pit produced by the cells. Results are as follows. Stannous fluoride and etidronate disodium showed statistically significant reduction of dentin resorption(p<0.05) but the effect of stannous fluoride seemed to be its high cytotoxicity. Etidronate disodium did not show cytotoxicities in all experimented concentrations. Gallium nitrate did not show differences in resorption either between different concentrations or from the control group.

• Bulletin of the Korean Chemical Society
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• v.25 no.1
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• pp.51-54
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• 2004

Gallium nitride (GaN) powders were prepared by calcining a gallium(III) nitrate salt in flowing ammonia in the temperature ranging from 500 to 1050 $^{\circ}C$. The process of conversion of the salt to GaN was monitored by X-ray diffraction and $^{71}Ga$ MAS (magic-angle spinning) NMR spectroscopy. The salt decomposed to ${\gamma}-Ga_2O_3$ and then converted to GaN without ${\gamma}-{\beta}Ga_2O_3$ phase transition. It is most likely that the conversion of ${\gamma}-Ga_2O_3$ to GaN does not proceed through $Ga_2O$ but stepwise via amorphous gallium oxynitride ($GaO_xN_y$) as intermediates. The GaN nanowires and microcrystals were obtained by calcining the pellet containing a mixture of ${\gamma}-Ga_2O_3$ and carbon in flowing ammonia at 900 $^{\circ}C$ for 15 h. The growth of the nanowire might be explained by the vapor-solid (VS) mechanism in a confined reactor. Room-temperature photoluminescence spectra of as-synthesized GaN powders obtained showed the emission peak at 363 nm.

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.6
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• pp.627-634
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• 2018

Gallium-based liquid metal, e.g., eutectic gallium-indium (EGaIn), is highly attractive as an electrode material for flexible and stretchable devices. On the liquid metal, oxide layer is spontaneously formed, which has a wide band-gap, and therefore is electrically insulating. In this paper, we fabricate a capacitor based on eutectic gallium-indium (EGaIn) liquid metal and investigate its cyclic voltammetry (CV) behavior. The EGaIn capacitor is composed of two EGaIn electrodes and electrolyte. CV curves reveal that the EGaIn capacitor shows the behavior of electric double-layer capacitors (EDLC), where the oxide layers on the EGaIn electrodes serves as the dielectric layer of EDLC. The oxide thicker than the spontaneously-formed native oxide decreases the capacitance of the EGaIn capacitor, due to increased voltage loss across the oxide layer. The EGaIn capacitor without oxide layer exhibits unstable CV curves during the repeated cycles, where self-repair characteristic of the oxide was observed. Finally, the electrolyte concentration is optimized by comparing the CV curves at various electrolyte concentrations.

• Resources Recycling
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• v.29 no.1
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• pp.81-88
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• 2020

Recovery of gallium and indium from waste light emitting diodes has been emphasized gradually owing to high content of gallium and indium. This study was established the recovery of gallium (Ga³⁺) and indium (In³⁺) from waste gallium nitride was contained in waste light-emitting diodes. The procedure was divided into the following steps; characteristic analysis, alkaline roasting, and leaching. In characteristic analysis part, the results were used as a theoretical basis for the acid leaching part, and the chemical composition of waste light emitting diodes is 70.32% Ga, 5.31% Si, 2.27% Al and 2.07% In. Secondly, with reduction of non-metallic components by alkaline roasting, gallium nitride was reacted into sodium gallium oxide, in this section, the optimal condition of alkaline roasting is that the furnace was soaked at 900℃ for 3 hours with mixing Na₂CO₃. Next, leaching of waste light emitting diodes was extremely important in the process of recovery of gallium and indium. The result of leaching efficiency was investigated on the optimal condition accounting for the acid agent, concentration of acid, the ratio of liquid and solid, and reaction time. The optimal condition of leaching procedures was carried out for 2.0M of HCl liquid-solid mass ratio of 30 ml/g in 32minutes at 25℃ and about 96.88% Ga and 96.61% In were leached.

• Resources Recycling
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• v.9 no.3
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• pp.29-36
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• 2000

A study on the recovery of gallium from leaching solutions is carried out by solvent extraction in order to produce gallium oxide of high purity. The results show that the extraction of gallium is found to be increase with acidities of aqueous solution up to 7.4 M/L when pure isopropyl ether is used. And the extraction of iron also increases with increasing acidity of aqueous solution. It appears that the separation of gallium from iron cannot be satisfactorily accomplished with isopropyl ether. But, in the case of extaction with D2EHPA, almost complete extraction of iron is achieved-leaving all the gallium in the aqueous solution-by maintaining the acidity of aqueous solution at 2 M/L. Accordingly, $Ga_2O_3{\cdot}H_2O$ of more than 99wt.% in purity can be produced from zinc residues through the processes comprising of alkali leaching, precipitation by neutralization and solvent extraction using isopropyl ether and D2EHPA as extractants.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.2
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• pp.11-18
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• 2022

Recently, as flexible electronic device-related technologies have received worldwide attention, the development of wiring and bonding technologies using liquid metals is required in order to improve problems such as formability in the manufacturing process of flexible devices and performance and durability in the bending state. In response to these needs, various studies are being conducted to use gallium and gallium-based alloys (eutectic Ga-In and eutectic Ga-In-Sn, etc.) liquid metals, with low viscosity and excellent electrical conductivity without toxicity, as low-temperature bonding materials. In this paper, the latest research trends of low-temperature bonding technology using gallium and gallium-based alloys are summarized and introduced. These technologies are expected to become important base technologies for practical use in the fields of manufacturing flexible electronic devices and low-temperature bonding in microelectronic packages in the future.

• Journal of the Korean Institute of Telematics and Electronics
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• v.10 no.3
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• pp.1-9
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• 1973

Gallium phosphide light emitting diode (LED) has been fabricated first time for pilot lamp and numeric display purposes. Bright red light is obtained in forward bias at very low current of one to five mA. A typical p-n junction is formed by liquid phase epitaxial growth on a n-type gallium physphide substrate. The crystal growth is achieved at about 1300$^{\circ}$K after the equilibrium of the gallium solution followed by tipping operation. The ohmic contact is made by wire bonding by thermal compression technique. The entire process is well fit for laboratory scale to fabricate a few hundred diodes for mainly demonstration purpose. For mass production, a large sum of the capital investment is required. The great merit of gallium phosphide LED is at low current operation, and green light emission is also obtainable by nitrogen doping.

• Restorative Dentistry and Endodontics
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• v.23 no.1
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• pp.269-277
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• 1998

This in vitro study compared the microleakage of 4 lining conditions when used with Gallium alloy GF II and Valiant PhD. Class V cavity was prepared on both buccal and lingual surface of 80 extracted human premolar & molar teeth with one margin in enamel and another in dentin. Before restoration, prepared cavities were applied to no-liner, cavity varnish, Scotchbond multipurpose, and Superbond D-liner II plus according to manufacture's instructions. The restored teeth were stored in saline for 1 week, then thermocycled for 100 times, stained with 0.5% basic fuchsin dye for 1 day, sectioned, and observed using a light microscope. Following results were obtained. 1. The leakage value of Superbond-lined group showed significantly lower than that of nolined group on both margins of Valiant PhD(p<0.05). 2; There was no significant difference between the 4 lining conditions in Gallium alloy GF II (p>0.05). 3. When We make a comparison between Gallium alloy GF II and Valiant PhD under same lining conditions, the microleakage value of Gallium alloy GF II showed lower than that of Valiant PhD on occlusal & gingival margin(p<0.05) except for Superbond-lined group(p>0.05).