材料结构与性能作业题Homework and Solution-2012

Homework

(Due Oct. 29, 2013)

1.Show that the minimum cation-to-anion radius ratio for a coordination number of

6 is 0.414 [Hint: use the NaCl crystal structure and assume that anions and cations

are just touching along tube edges and across face diagonals.

2.In terms of bonding, explain why silicate materials have relatively low density.

3.If cupric oxide (CuO) is exposed to reducing atmospheres at elevated

temperatures, some of the Cu2+ ions will become Cu+.

a)name one crystalline defect that you would expect to form in order to

maintain charge neutrality under these conditions,

b)How many Cu+ ions are required for the creation of each defect?

c)How would you express the chemical formula for this nonstoichiometric

material?.

4.The modulus of elasticity for titanium carbide (TiC) having 5 vol% porosity is 310

GPa (6

45⨯psi). a) Calculate the modulus of elasticity for the nonporous 10

material. b) At what volume percent porosity will the modulus of elasticity be 240 GPa (6

10

35⨯psi)?

5.Calculate the room-temperature electrical conductivity of silicon that has been

doped with 2×1024m−3 of boron atoms.

6.Explain why a brass lid ring on a glass canning jar will loosen when heated. Suppose

the ring is made of tungsten instead of brass. What will be the effect of heating the lid and the jar? Why?

7.Zinc telluride has a band gap of 2.26 eV. Over what range of wavelengths of

visible light is it transparent? What might be its color?

8.Selecting one of the advanced materials listed below（including, but not limited

to）, mak e a PPT with text and graphics to describe characteristics and applications of the materials, then present your PPT in class in 5 minites .

TiNi-based Shape memory alloy，GaAs photonic crystal，LiNbO3 laser crystal，PZT pizeoelectrics，NiCuZn-ferrite，BiFeO3 multiferroics，ZnO Nanorods，graphene，Fullerene，cathode materials for Li-ion batteries，amorphous silicon thin film transistors，polycrystalline silicon thin films by vacuum evaporation，carbon nanotube membrane，Nonlinear Optical Crystals，etc.

(List all your references. Answers without proper references will receive no credit.)