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4. The Structure of Crystalline Soids 1 4.1 Introduction • 금속의 결정 구조 • X-선 회절 기법을 통한 결정 구조의 조사 • 금속 결합: 방향성이 없어 인접 원자 개수에 제약이 없음. (Dense packing) Energy r typical neighbor bond length typical neighbor bond energy Energy r typical neighbor bond length typical neighbor bond energy Energy r typical neighbor bond length typical neighbor bond energy Energy r typical neighbor bond length typical neighbor bond energy
Transcript of 4. The Structure of Crystalline Soids
4. The Structure of Crystalline Soids
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4.1 Introduction
• 금속의결정구조
• X-선회절기법을통한결정구조의조사
• 금속결합: 방향성이없어인접원자개수에제약이없음.
(Dense packing)
Energy
r
typical neighborbond length
typical neighborbond energy
Energy
r
typical neighborbond length
typical neighborbond energy
Energy
r
typical neighborbond length
typical neighborbond energy
Energy
r
typical neighborbond length
typical neighborbond energy
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4.2 Face-centered Cubic Crystal Structure
- Aluminum, Copper, Silver, Gold
- 각 ion core는면의대각선에서접한다.
( a : cube edge length, R : atomic radius )
- corner atom의 1/8, face-centered atom의 1/2
- CN(인접한원자의개수) : 12
- APF(단위정에서 sphere가차지하는체적비) : 0.74
22Ra
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4.3 Body-centered Cubic Crystal Structure
- α철, Chromium, Molybdenum, Tungsten
- 각 ion core는 cube의대각선에서접한다.
- corner atom의 1/8, body-centered atom의 1/1
- Coordination number : 8
- Atomic Packing Factor : 0.68
3
4Ra
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4.4 Hexagonal Close-Packed Crystal Structure(육방조밀구조)
- Cadmium, Magnesium, Titanium, Zinc
- c/a = 1.633
- 상하면의 corner atom의 1/6, center atom의 1/2 및중간층 3개
- CN : 12
- APF : 0.74
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4. The Structure of Crystalline Soids
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예제 4.1> Calculate the volume of an FCC unit cell in terms of the
atomic radius R.
예제 4.2> Show that the atomic packing factor for the FCC crystal
structure is 0.74.
예제 4.3> HCP단위정의부피계산
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4.5 Density Computation
n : unit cell 당원자의개수
A : atomic weight
Vc : unit cell의부피
NA : Avogadro 수
예제 4.4> 구리는원자의반지름이 0.128nm, FCC구조를가지며, 원자량이 63.5g/mol 이다. 밀도를계산하고측정값과비교하라.
Ac NV
nA
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4.14 Polymorphism(동질이상)과
Allotropy(동소체)
• 동일금속/비금속이하나이상의결정
구조를가지는경우
• 탄소(흑연/다이아몬드), 철(BCC/FCC)
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4.15 Atomic Arrangements
- Family (예, FCC의 {100})
4.16 Linear and Planar Density
vector ldirectiona of length
vector direction on
centered atoms ofnumber
LD
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• 소성변형과 Planar/Linear Density
4.17 Close-Packed(조밀) Crystal Structures
• FCC와 HCP의APF : 0.74 (가장조밀한구조)
plane of area
plane a on centered atoms ofnumber PD
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4.18 X-ray Diffraction : Determination of Crystal Structure
* Single crystal growth
