• Korean Journal of Materials Research
• /
• v.28 no.12
• /
• pp.732-737
• /
• 2018

We develop a purification process of $Hg_2Br_2$ raw powders using a physical vapor transport(PVT) process, which is essential for the fabrication of a high performance acousto-optic tunable filter(AOTF) module. Specifically, we characterize and compare three $Hg_2Br_2$ powders: $Hg_2Br_2$ raw powder, $Hg_2Br_2$ powder purified under pumping conditions, and $Hg_2Br_2$ powder purified under vacuum sealing. Before and after purification, we characterize the powder samples through X-ray diffraction and X-ray photoelectron spectroscopy. The corresponding results indicate that physical properties of the $Hg_2Br_2$ compound are not damaged even after the purification process. The impurities and concentration in the purified $Hg_2Br_2$ powder are evaluated by inductively coupled plasma-mass spectroscopy. Notably, compared to the sample purified under pumping conditions, the purification process under vacuum sealing results in a higher purity $Hg_2Br_2$ (99.999 %). In addition, when the second vacuum sealing purification process is performed, the remaining impurities are almost removed, giving rise to $Hg_2Br_2$ with ultra-high purity. This high purification process might be possible due to independent control of impurities and $Hg_2Br_2$ materials under the optimized vacuum sealing. Preparation of such a highly purified $Hg_2Br_2$ materials will pave a promising way toward a high-quality $Hg_2Br_2$ single crystal and then high performance AOTF modules.

• Korean Chemical Engineering Research
• /
• v.62 no.3
• /
• pp.246-252
• /
• 2024

In this study, impurities such as Li and F were removed from waste graphite through citric acid treatment, and changes in structural properties, capacity, and cycle stability of regenerated graphite were observed accordingly. Regenerated graphite pretreated in a nitrogen atmosphere was treated with citric acid, and its structure and characteristics were analyzed through SEM (Scanning Electron Microscope), FT-IR (Fourier Transform Infrared spectroscopy), XRD (X-ray Diffraction), and XPS (X-ray Photoelectron Spectroscopy). Waste graphite that was not treated with acid had a rapid decrease in capacity before 70 cycles, but graphite that had been treated with citric acid showed a capacity of 302.9 mAh g^-1 and a capacity retention rate of 93.1% at 100 cycles. In addition, despite changes in current density in rate performance, samples treated with citric acid showed 340.2 mAh g^-1 performance at 1.0C without change in capacity. As a result, it was confirmed that citric acid treatment not only effectively removed impurities and showed a high capacity retention rate, but also showed stability even at high current densities.

• The Korean Journal of Ceramics
• /
• v.2 no.4
• /
• pp.177-180
• /
• 1996

Considerable progress in the development of CVD techniques for the deposition of diamond films has been achieved recently. Despite the polycrystalline structure of this material, its physical properties are now approaching those of natural type IIa diamond crystals. This paper will given some insight into the current status of CVD diamond thechnology with emphasis on optical and thermal applications. The role of process gas impurities like nitrogen will be discussed.

• Journal of Environmental Science International
• /
• v.8 no.2
• /
• pp.233-240
• /
• 1999

Industrial waste which highly loaded by halogenide phenols was photooxidized by laboratory-scale photooxidation of these organic impurities in the presence of aerotropic and titaniumdioxide as photocatalyst. The disapperance of organic compounds was determined as a function of the irradiation time. Some contaminants such as 2-chlorophenol, 2-bromphenol, 3-bromphenol, 4-bromphenol, 2,4-dibromophenol and 2,6-dibromophenol were photodegraded separately to obtain information on the reaction rates, reactivities, and reaction mechanisms of the photooxidation, and on the stoichiometric correlation between organic reactant and inorganic products concentration in the course of the photocatalytic photoreaction.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.11a
• /
• pp.92-92
• /
• 2009

In the present study, impurities doped GxZO thin films were prepared by dc-magnetron sputtering on glass substrate and effect of processing variables on the growth behavior was investigated.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.22 no.4
• /
• pp.500-509
• /
• 1993

Pectins present in the primary cell walls and middle lamellae of plant cell walls are extracted by water, cheating agents, acid or alkali solutions. However, some neutral contaminating components are extracted in conjunction with pectins during the extraction process. Thus, the accurate characterization of physi-cochemical properties of pectins necessitates to get rid of the impurities. In this review, dialysis, alcohol precipitation, ion exchange chromatography and metal precipitation were compared as procedures to purify the pectin extracts. In addition, the chemical methods to analyze pectins are discussed in terms of three major chemical constituents, i.e., anhydrogalacturonic acid, methoxyl groups and neutral sugars.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2006.08a
• /
• pp.375-378
• /
• 2006

Characteristics of doped MgO layer deposited under hydrogen atmosphere were investigated. Hydrogen gas was introduced during e-beam evaporation of doped MgO and its effects on microstructure, cathodoluminescence, discharge voltages and effective yield of secondary electron emission were examined. The results indicated that the hydrogen influences and doped impurities the concentration and energy levels of defects in MgO layer and that affects the luminance efficiency and discharge delays of the panels significantly.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2009.05a
• /
• pp.121-121
• /
• 2009

구리 전해정련 과정에서 전해액 중의 Arsenic과 같은 불순물 성분이 전기동의 전착에 미치는 영향을 확인하고, 전해액 중의 최대 허용 농도를 도출하고자 하였다. 전해정련 과정에서 분순물 성분이 전기동 전착에 미치는 영향을 주사전자현미경(SEM), X-선 회절(X-ray diffraction) 및 전기화학적 분석을 통해 수행하였다.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2005.11a
• /
• pp.100-101
• /
• 2005

• Textile Coloration and Finishing
• /
• v.22 no.1
• /
• pp.8-13
• /
• 2010

Needle contamination was investigated using a test rig simulated the knitting points in the knitting machine in relation with the characteristics of knitting yarn such as yarn type and moisture contents. When used open-end yarn compared with combed and carded ring-spun yarns, the needle contamination was significantly increased because of the higher friction between yarn and needle by the fly and other impurities. Also Lower moisture content of the yarns aggravated the needle contamination. In addition knitting yarn breakage was substantially influenced by the higher needle contamination.