ENME 421 Midterm 3

23 flashcards · Other · by Dylan Matwe

1. What is ceramic composition when rcation/ranionr_{cation}/r_{anion} rcation​/ranion​ < 0.155

   Coord. Number = 2 Arrangement: Linear

2. What is ceramic composition when 0.155< rcation/ranionr_{cation}/r_{anion} rcation​/ranion​ < 0.225

   Coord. Number = 3 Triangular

3. What is ceramic composition when 0.225< rcation/ranionr_{cation}/r_{anion} rcation​/ranion​ < 0.414

   Coord. Number = 4 Tetrahedral

4. What is ceramic composition when 0.414< rcation/ranionr_{cation}/r_{anion}rcation​/ranion​ < 0.736

   Coord. Number = 6 Octahedral

5. What at is ceramic composition when 0.736< rcation/ranionr_{cation}/r_{anion}rcation​/ranion​ < 1

   Coord. Number = 8 Cubic

6. Rock Salt Structure

   AX Also called NaCl structure Cations octahedral sites ∴ 0.414< rcation/ranionr_{cation}/r_{anion}rcation​/ranion​ < 0.736 FCC of anions with cation in the center and corners Make sure you can draw this

7. Cesium Chloride Structure

   Anions are at the corners with a single cation in the center AX type Interchange of Cations and Anions prodduces the same structure Not a BCC crystal Cubic Sites perfered ∴0.736< rcation/ranionr_{cation}/r_{anion}rcation​/ranion​ < 1

8. Zinc Blend or Sphalerite Structure

   Name after zinc AX Type Coordination is 4 i.e. tetrahedral condition ∴0.225< rcation/ranionr_{cation}/r_{anion}rcation​/ranion​ < 0.414 All the corners of the cubic cell are occupied by S atoms where the Zn fill the interor

9. Fluorite Structure

   AX2AX_2AX2​ Crystal strucutre CN of 8, i.e. cubic ∴0.736< rcation/ranionr_{cation}/r_{anion}rcation​/ranion​ < 1 Calcium ions are positioned at the center with fluorine a the corners Unit cell consists of eight cubes

10. Perovskite Structure

    ABX3ABX_3ABX3​ Strucutre Some on corners some in the middle some on the faces

11. List the 5 stages of ductile faliure in the right order

    Necking Void nucleation Void Growth and Coalescence Crack Propogation Fracture

12. How did this material fail? Explain using appropriate terminologies'?

    This material failed by Fatigue. Evidence of crack initiation from the “keyway” corner and propagation characterized by beachmarks suggests fatigue failure.

13. Look at this picture of Polymer Crystallinity!

    Wow it looks so cool

14. What structure when the ceramic is: AX 0.414 < rcation/ranionr_{cation}/r_{anion}rcation​/ranion​ < 0.732

    Rock Salt

15. What structure when the ceramic is: AXAXAX 0.732 < rcation/ranionr_{cation}/r_{anion}rcation​/ranion​ < 1.0

    Cesium Chloride

16. What structure when the ceramic is: AXAXAX 0.225< rcation/ranionr_{cation}/r_{anion}rcation​/ranion​ < 0.414

    Zinc Blend or Sphalerite Structure

17. What are the radius bounds of the Rock Salt structure?

    0.414 < rcation/ranionr_{cation}/r_{anion}rcation​/ranion​ < 0.732

18. What are the radius bounds of Cesium Chloride structure?

    0.732 < rcation/ranionr_{cation}/r_{anion}rcation​/ranion​ < 1.0

19. What are the radius bounds of Zinc Blende structure?

    0.225< rcation/ranionr_{cation}/r_{anion}rcation​/ranion​ < 0.414

20. Co to za istota?

    This is the cubic or cesium chloride structure

21. Co to za istota?

    Octahedral or NaCl structure

22. Co to za istota

    Tethrahedral ZnS structure

23. Can you draw all the crystal structures?

    Absolutely, I am an artist