• Title/Summary/Keyword: Rare metals

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P2O5-ZnO-SiO2-R2O Glass Frit Materials for Hermetic Sealing of Dye-Sensitized Solar Cells

  • Lee, Hansol;Lee, Choon Yeob;Hwang, Jae Kwun;Chung, Woon Jin
    • Journal of the Korean Ceramic Society
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    • v.54 no.5
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    • pp.400-405
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    • 2017
  • $P_2O_5-ZnO-SiO_2-R_2O$ glasses were synthesized as a sealing material for large scale dye-sensitized solar cells (DSSC). Compositional effects of $P_2O_5$ and ZnO were examined by varying their contents. Their viscosity and glass stability at sintering temperatures of less than $550^{\circ}C$ were examined by flow button test. Glass transition temperature and structural change upon compositional change were investigated. Chemical stability against electrolyte was also examined by immersing the glasses in the electrolyte for 72 h at $85^{\circ}C$.

Content and Distribution of Transition Metals and Rare Earth Elements in Magnetically and Mechanically Separated Brown Coal Ash

  • Malikov, Sh.R.;Pikul, V.P.;Mukhamedshina, N.M.;Sandalov, V.N.;Kudiratov, S.;Ibragimova, E.M.
    • Journal of Magnetics
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    • v.18 no.3
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    • pp.365-369
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    • 2013
  • Coal ash is known to contain a noticeable amount of valuable elements, including transition metals and lanthanides. Therefore it is quite actual problem to extract them for metallurgy and other applications. This paper presents the results of high gradient magnetic and mechanical separation, microscopy, element analyses and optical spectroscopy of brown coal ash taken from the combustion camera and chimney-stalk of Angren thermal power station. The separated magnetic fraction was 3.4 wt.%, where the content of Fe in ferrospheres increased to 58 wt.%. The highest contents of Fe and rare earth elements were found in the fine fractions of $50-100{\mu}m$. Optical absorption spectroscopy of water solutions of the magnetic fractions revealed $Fe^{2+}$ and $Fe^{3+}$ ions in the ratio of ~1:1. The separated coal ash could be used for cleaning of technological liquid waste by means of the high gradient magnetic field.

Afterglow Effect from Adding BaF2 to Oxyfluoride Glass Ceramic Containing Eu2+-doped Nepheline

  • Lee, Hansol;Chung, Woon Jin
    • Current Optics and Photonics
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    • v.6 no.4
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    • pp.413-419
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    • 2022
  • An oxyfluoride glass ceramic containing Eu2+-doped nepheline and LaF3 crystals was modified, with BaF2 replacing LaF3 up to 20 mole percent, and its luminescence change was monitored. With increasing BaF2 content, the greenish yellow emission centered at 540 nm under 400-nm excitation decreased, and a new afterglow emission from the modified ceramic was observed after removal of the excitation light source. X-ray diffraction (XRD) and transmission electron microscopy with energy dispersive spectroscopy (TEM-EDS) were used to investigate the changes in the crystalline phases within the glass matrix. Time dependent emission intensity was monitored to observe the afterglow, and the possible mechanism for the afterglow due to BaF2 addition was considered.

A Preliminary Geochemical Study on the Khaldzan-Buregtei Pegmatite, Western Mongolia (몽골 서부 할잔-부룩테이 페그마타이트에 대한 지화학적 예비 연구)

  • Pak, Sang-Joon;Heo, Chul-Ho;Kim, You-Dong
    • Journal of the Mineralogical Society of Korea
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    • v.21 no.3
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    • pp.261-269
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    • 2008
  • A NYF-type (Nb-Y-Zr-F) Khaldzan-Buregtei pegmatite containing rare-earth metals occurs within alkali granitoid complex of the western Mongolia. The pegmatites are considered as differentiates of syenites and alkali feldpar granitic rocks, showing that their rare-earth element concentrations are enriched tens times higher than those from the adjacent alkali granitic rocks. It is suggested that econemic aspects of the pegmatites can be controlled by the magnitude of lateral and vertical extensions and local grade variation of REE-bearing pegmatites.

A Study on the Properties of Design for the Biomaterial Ti-Ag-Zr Alloys Using DV-Xα Molecular Orbital Method (DV-Xα 분자궤도법으로 설계한 생체용 Ti-Ag-Zr 합금 특성 평가)

  • Baek, Min-Sook;Yoon, Dong-Joo;Kim, Byung-Il
    • Korean Journal of Materials Research
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    • v.24 no.4
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    • pp.175-179
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    • 2014
  • Ti and Ti alloys have been extensively used in the medical and dental fields because of their good corrosion resistance, high strength to density ratio and especially, their low elastic modulus compared to other metallic materials. Recent trends in biomaterials research have focused on development of metallic alloys with elastic modulus similar to natural bone, however, many candidate materials also contain toxic elements that would be biologically harmful. In this study, new Ti based alloys which do not contain the toxic metallic components were developed using a theoretical method (DV-$X{\alpha}$). In addition, alloys were developed with improved mechanical properties and corrosion resistance. Ternary Ti-Ag-Zr alloys consisting of biocompatible alloying elements were produced to investigate the alloying effect on microstructure, corrosion resistance, mechanical properties and biocompatibility. The effects of various contents of Zr on the mechanical properties and biocompatibility were compared. The alloys exhibited higher strength and corrosion resistance than pure Ti, had antibacterial properties, and were not observed to be cytotoxic. Of the designed alloys' mechanical properties and biocompatibility, the Ti-3Ag-0.5Zr alloy had the best results.

Comparison of the Chemical Reactivity between Sulfuric and Methanesulfonic Acids as a Leaching Agent (침출제로 황산과 메탄술폰산의 화학적 반응성 비교)

  • Tran, Thanh Tuan;Moon, Hyun Seung;Lee, Man Seung
    • Resources Recycling
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    • v.30 no.3
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    • pp.41-46
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    • 2021
  • Methanesulfonic acid (MSA) can be considered effective in the leaching of metals because of its advantageous physical and chemical properties. The chemical reactivities of MSA and sulfuric acid were compared based on their structures and the dissolution data of Co and Ni metal. The inductive and resonance effects play a vital role in the chemical reactivities of these two acids. The dissolution percentages of Co and Ni in the sulfuric acid solution were higher than those in the MSA solution under the same experimental conditions. Considering the strong acidity of MSA and the high solubility of its metal salts, MSA can be employed as a leaching agent for the recovery of metals.

Preparation of Graphene-Palladium Composite by Aerosol Process and It's Characterization for Glucose Biosensor (에어로졸 공정에 의한 그래핀-팔라듐 복합체 제조 및 글루코스 바이오센서 특성평가)

  • Kim, Sun Kyung;Jang, Hee Dong;Chang, Hankwon;Choi, Jeong-Woo
    • Particle and aerosol research
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    • v.10 no.2
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    • pp.53-59
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    • 2014
  • Palladium (Pd) nanoparticles attached graphene (GR) composite was synthesized for an enhanced glucose biosensor. Aerosol spray pyrolysis (ASP) was employed to synthesize the GR-Pd composite using a colloidal mixture of graphene oxide (GO) and palladium chloride ($PdCl_2$) precursor. The effects of the weight ratio of the Pd/GR on the particle properties including the morphology and crystal structure were investigated. The morphology of GR-Pd composites was generally the shape of a crumpled paper ball, and the average composite size was about $1{\mu}m$. Pd nanoparticles less than 20 nm in diameter were deposited on GR sheets and the Pd nanoparticles showed clear crystallinity. The characteristic of the glucose biosensor fabricated with the as-prepared GR-Pd composite was tested through cyclic voltammetry measurements. The biosensor exhibited a high current flow as well as clear redox peaks, which resulted in a superior ability of the catalyst in terms of an electrochemical reaction. The highest sensitivity obtained from the amperometric response of the glucose biosensor was $14.4{\mu}A/mM{\cdot}cm^2$.

Trend on the Recycling Technologies for Silicon Sludge by the Patent and Paper Analysis (특허(特許)와 논문(論文)으로 본 실리콘 슬러지의 재활용(再活用) 기술(技術) 동향(動向))

  • Jang, Hee-Dong;Kil, Dae-Sup;Chang, Han-Kwon;Cho, Young-Ju;Cho, Bong-Gyoo
    • Resources Recycling
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    • v.21 no.4
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    • pp.60-68
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    • 2012
  • Silicon wafer for making semiconductor devices and solar cell is used in the semiconductor and solar industry, respectively. Silicon wafer is produced by cutting with silicon ingot and sludge contains silicon occurs from cutting process. Generation of silicon sludge is increasing on developing all industry sectors which have need of semiconductor device. These days it has been widely studied for the recycling technologies of the silicon sludge from view points of economy and efficiency. In this paper, patents and paper on the recycling technologies of the silicon sludge were analyzed. The range of search was limited in the open patents of USA (US), European Union (EU), Japan (JP), Korea (KR) and SCI journals from 1982 to 2011. Patents and journals were collected using key-words searching and filtered by filtering criteria. The trends of the patents and journals was analyzed by the years, countries, companies, and technologies.

Effect of Al, Al2O3 Dispersants and Heat Treatment on Deposits from Watt′s Ni Plating Bamth (와트 Ni 도금욕에서 도금 피막에 미치는 Al, Al2O3 분산제 및 열처리의 영향)

  • Lee, Sang-Baek;Park, Hyeong-Ho;Bae, In-Seong;Yun, Jae-Sik;Kim, Byeong-Il
    • Korean Journal of Materials Research
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    • v.12 no.2
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    • pp.153-159
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    • 2002
  • The co-deposited behavior was investigated under varied bath compositions and current densities from Watt Ni plating bath containing Al and A1$_2$O$_3$powders. For single-particle bath, Al and A1$_2$O$_3$particles were agglomerated. The area percentage of A1$_2$O$_3$on plating surface decreased with increasing the current density, while that of Al on plating surface increased. On the other hand, in case of double-particle bath with 1.25g/$\ell$ of Al and 5.0g/$\ell$ of A1$_2$O$_3$5g, the area percentage of Ni-Al-A1$_2$O$_3$increased with increasing current density and the surface morphology was fine without agglomeration. Intermetallic compounds such as $\gamma$'and $\gamma$+$\gamma$' phases appeared when the co-deposited film was annealed.