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침상형 은 미세 입자의 합성

Title
침상형 은 미세 입자의 합성
Other Titles
Synthesis of Needle-like Silver Microparticles
Author
이채성
Alternative Author(s)
Lee, Chae Sung
Advisor(s)
김호건
Issue Date
2011-02
Publisher
한양대학교
Degree
Master
Abstract
본 연구에서는 금속염의 화학적 환원법을 이용하여, 중간체의 형상을 그대로 반영한 은 미세 입자를 제조하였다. 화학 반응 시 원래의 형상을 유지한 채 다른 물질로 바뀌는 것은 무기 재료 공정상 중요한 process의 하나이나, 그 예가 산화철 외에 알려진 것이 없다. 본 연구에서는 AgNO3을 은으로 환원하는 과정에서 균일 침전제 urea를 사용하였을 때 침상의silver isocyanate 중간체가 형성되었고 이를 환원제 NaBH4로 환원하면 중간체의 형상을 반영한 침상의 은으로 변화하는 것을 발견하였다. 본 연구에서는 이 현상을 이용하여 침상의 은 미세 입자를 균일하게 합성하는 기초 과정을 조사하였다. 형상과 관련하여 용매, 요소의 농도, pH와 환원제 농도의 효과를 조사하기 위해 각 공정에서 반응 조건을 달리하여 합성하였다. 형성된 입자들의 결정상, 미세 구조를 확인하기 위해 XRD, SEM을 측정하였고 실험 결과 다음의 결과를 얻었다. (1) 요소의 농도가 증가할수록 핵생성이 성장을 저해하여 입자의 크기는 작아졌다. (2) 용매의 분자량이 증가할수록 (ethyl alcohol < isopropyl alcohol < n-octyl alcohol) 용해도가 낮아져 국소부위에서만 반응이 발생하여 입자의 크기가 크고 응집이 심하였다. (3) NH4OH 투입량이 증가함에 따라 pH가 증가하여 핵 성장이 저해되었다. 2ml 부터는 핵형성 과다로 인하여 침전물이 생성되지 않았고, 1ml 이하에서는 생성된 핵이 성장하여 침전물이 생성되었으나, 입자 크기에는 큰 영향을 미치지 않았다. (4) 환원제 농도의 증가에 따라 입자의 크기는 감소하였다. 위의 결과를 종합하였을 때 침상은 미세 입자 합성의 최적 조건은 ethyl alcohol 용매를 사용하여 AgNO3(0.04 M), urea(1.0 M)이고, 환원제(NaBH4)를 0.2 M로 유지했을 때인 것으로 판단되었다.| Shape control is one of the important inorganic material processes, and among them maintaining the original shape of reaction intermediates has been known to be difficult. For example, iron oxide is the only example known for this interesting shape control reaction in the literature. In this study, needle-like shaped silver microparticles, whose shape is dictated by a reaction intermediate, were synthesized by a simple chemical reduction method. The reaction intermediate used in this study was silver isocyanate, which was obtained by the chemical reaction of silver nitrate and urea. An optima reaction condition was investigated in terms of solvents, urea concentration, pH, and reducing agent concentrations, and their effect on the shape and size of silver microparticles was studied through XRD and SEM. The best reaction condition for the needle-like shaped silver microparticles was found to be as follows: AgNO3(0.04M),urea(1.0M), NaBH4(0.2M) in ethyl alcohol.
Shape control is one of the important inorganic material processes, and among them maintaining the original shape of reaction intermediates has been known to be difficult. For example, iron oxide is the only example known for this interesting shape control reaction in the literature. In this study, needle-like shaped silver microparticles, whose shape is dictated by a reaction intermediate, were synthesized by a simple chemical reduction method. The reaction intermediate used in this study was silver isocyanate, which was obtained by the chemical reaction of silver nitrate and urea. An optima reaction condition was investigated in terms of solvents, urea concentration, pH, and reducing agent concentrations, and their effect on the shape and size of silver microparticles was studied through XRD and SEM. The best reaction condition for the needle-like shaped silver microparticles was found to be as follows: AgNO3(0.04M),urea(1.0M), NaBH4(0.2M) in ethyl alcohol.
URI
https://repository.hanyang.ac.kr/handle/20.500.11754/140186http://hanyang.dcollection.net/common/orgView/200000416910
Appears in Collections:
GRADUATE SCHOOL[S](대학원) > APPLIED CHEMISTRY(응용화학과) > Theses (Master)
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