• Economic and Environmental Geology
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• v.50 no.6
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• pp.509-515
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• 2017

Quartz is the most abundant mineral in the Earth's continental crust. Therefore, understanding of quartz dissolution and precipitation is very important to know about weathering processes and interactions between rocks and water in hydrothermal and metamorphic environments. This paper presents a basic review on the research about quartz dissolution mechanism under various physico-chemical conditions. We rearranged the relationship between each physico-chemical factor and dissolution mechanism from the results of previous researchers in this paper. From this result, we understood that quartz dissolution and precipitation are affected by each factor such as temperature, pH, and applied stress conditions at contact point. In particular, we recognized that the high pH and temperature conditions have different anion concentrations on mineral's surface. As a result, high pH and temperature conditions have a better effect than applied stress condition to the quartz dissolution mechanism.

• The Journal of Engineering Geology
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• v.20 no.3
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• pp.271-279
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• 2010

Time-dependent behavior similar to secondary deformation related to mineral dissolution is easily observed when performing a laboratory pressure experiment. In this research, to observe the dissolution of quartz found in bentonite used as buffer material for the geological disposal of high-level waste (HLW) under conditions of high pH, we calculated the diffusion of $OH^-$ ions and the behavior of quartz dissolution using the homogenization analysis method. The results reveal that the rate of quartz dissolution is proportional to the temperature and interlayer water thickness. In particular, in a high-pH environment, the reacted area (and therefore the dissolution rate) increases with decreasing interlayer water thickness.

• Economic and Environmental Geology
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• v.42 no.4
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• pp.335-342
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• 2009

The effects of bacterial lysis on the rate of quartz dissolution were investigated under pH 7 condition using Bacillus subtilis cells which were either irradiated or non-irradiated with gamma ray. The amount of dissolved organic carbon (DOC) which resulted from bacterial lysis increased in slurries of quartz and bacteria mixture over experimental period. Lysis of non-irradiated bacteria led to the elevated concentration of dissolved silicon when compared with abiotic control. Concomitant increase in the amounts of DOC and dissolved silicon over time indicated that lixiviation of silicon from quartz was due to bacterial lysis. Higher amounts of DOC and dissolved silicon were present in the irradiated bacterial slurries than those of non-irradiated bacteria. The enhancement of quartz dissolution in the irradiated bacterial slurries was likely attributed to disruption of organic molecules in the bacterial cells by gamma ray and formation of effective ligands for quartz dissolution. The results suggest that the effects of bacterial lysis on mineral weathering rate should be considered for prediction of time for released radionuclides to migrate to surface biosphere in high level radioactive waste disposal site.

• Proceedings of the Korean Vacuum Society Conference
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• 1996.06a
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• pp.164-165
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• 1996

임피던스 pprobe와 고전압 pprobe를 이용하여 평판형 유도결합 플라즈마에서의 용 량 결합 성분을 구하였으며, 용량 결합 성분에 의해서 생기는 석영창의 손상을 4극 질량 분 석기(quadruppole mass sppectrometer)를 이용하여 확인하였다. 또한 축방향 외부 자장을 가 하였을 경우 용량 결합 성분이 상당량 감소하여 석영창의 손상이 거의 없음을 확인하였다.

• Applied Chemistry for Engineering
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• v.31 no.6
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• pp.697-700
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• 2020

We report the synthesis and characterization of quartz nanocrystals (NCs). Quartz NCs were synthesized from the dissolution of amorphous silica nanoparticle precursors under the mild hydrothermal condition of ~250 ℃ and autogenic pressure. It was confirmed that the average size of the nanostructure with a highly crystalline phase of α-quartz can be tuned in a relatively narrow range from 407.5 to 826.2 nm with respect to the reaction time. α-Quartz NCs have potential uses for technological applications in optoelectronics, sensing, and rechargeable battery devices.

• Economic and Environmental Geology
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• v.39 no.5 s.180
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• pp.583-595
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• 2006

Quartz veins from the Hwawon area are an epithermal quartz vein that is filling the fault zone within Precambrian metasedimentary rocks and Jurassic granite. Mineralization can be divided into hypogene and supergene stages. Hypogene stage is associated with hydrothermal alteration minerals(propylitic and argillic zones) such as epidote, chlorite, illite, sericite and sulfides such as pyrite, sphalerite, chalcopyrite, galena, bornite, cubanite, argentian tetrahedrite, Pb-Ag-S system and Pb-Te-S system. Supergene stage is composed of Fe-Mn oxide, Zn-Fe oxide and Pb oxide. Fluid inclusion data indicate that homogenization temperatures and salinity of hypogene stage range from $291.2^{\circ}C$ to $397.3^{\circ}C$ and from 0.0 to 9.3 wt.% eq. NaCl, respectively. It suggests that ore forming fluids were cooled and diluted with the mixing of meteoric water. Oxygen($-0.7{\sim}3.5%_{\circ}$(white quartz: $-0.7{\sim}3.5%_{\circ}$, transparent quartz: $2.4%_{\circ}$)) and hydrogen($-70{\sim}55%_{\circ}$(white quartz: $-70{\sim}55%_{\circ}$, transparent quartz: $-62%_{\circ}$)) isotopic composition indicates that hydrothermal fluids were derived from magmatic and evolved by mixing with meteoric water during mineralization.

• Polymer Science and Technology
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• v.13 no.1
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• pp.23-27
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• 2002

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.321-321
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• 2013

열전재료는 열과 전기의 변환이 상호 가역적으로 일어나는 현상을 갖는 재료로서, 사용온도별로 여러 가지 재료가 개발되고 있다. 중온 영역에서 우수한 열전특성을 보이는 skutterudite는 격자 내에 2개의 공극을 갖고 있고 이에 적절한 원자를 충진하여 포논산란을 유도하고, PGEC(phonon-glass and electron-crystal) 개념을 적용하여 재료의 열적인 성질과 전기적인 성질을 동시에 제어함으로써 열전성능의 향상을 도모할 수 있는 재료이다. 본 연구에서는 챔버 내부 기체를 연속적으로 뽑아내어 진공도를 유지하는 방식이 아닌, 석영관을 앰플화한 진공밀폐 용해법을 사용하였다. 진공밀폐 용해법은 성분원소의 산화와 휘발을 억제하는데 있어 매우 유용한 공정이다. 용해를 통해 얻어진 잉곳을 용해와 동일한 방법으로 석영관에 밀봉하여 873 K에서 100시간 동안 진공열처리를 실시하였다. 또한, 합성된 잉곳의 기계적 특성 향상을 위해 $75{\mu}m$ 이하로 파쇄하여 진공 열간 압축 소결하였다. La가 충진된 $La_zCo_4Sb_{12}$ Skutterudites 단일상을 합성하여 La의 충진량(z)에 따른 열전특성과 전자이동특성을 조사하였다.

• Proceedings of the KAIS Fall Conference
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• 2006.11a
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• pp.272-275
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• 2006

본 논문에서는 CMP(Chemical Mechanical Polishing) 슬러리용으로 사용되는 저가이면서 입도 분포가 균일한 콜로이달 실리카(Colloidal Silica)를 사용하여 추가의 첨가제 없이 열처리 공정만을 거쳐 석영유리를 제조하여 6N의 순도와 1 mm 두께 기준 86%의 자외선 투과율 그리고 AFM(Atomic Force Microscopy) 및 간섭계 현미경을 이용하여 표면의 거칠기가 1 nm 미만인 고순도 석영유리를 제조하였다.

• The Journal of Engineering Research
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• v.3 no.1
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• pp.223-233
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• 1998

The kinetic and mechanism of the hydrothermal reaction between lime and quartz used solid state reaction equations have been investigated. Hydrothermal reaction on the starting materials was carried out in an autoclave that quartz mixed with calcium hydroxide in CaO/$SiO_2$ ratio of 0.8-1.0 for 0.5-8 hour at saturated steam pressure of $180-200^{\circ}C$. The rate of reaction was given from the ratio of uncombined lime and quartz content to the total lime and quartz content. The rate of reaction was obtained the results by the Jander's equation $[1-(1-\alpha)^{1/3}]^N=Kt$. The reaction of lime is controlled mainly by the dissolution such as N=1, and the reaction of quartz is controlled mostly by the diffusion such as $N\risingdotseq2$. The rate of hydrothermal reaction in the calcium silicate hydrates system is suggested to be determined generally by the mass transfer through the product laver formed around the reactant particles. The rate equation for whole hydrothermal reaction is shown that it is converted into the rate determining step by the diffusion from the boundary reaction such as approximately $N=1-2$.