《材料科学与工程基础》英文影印版习题及思考(20)

《材料科学与工程基础》英文习题及思考题及答案,本人从网上狂搜,兄弟们姐妹们狂下啊,不要辜负我的劳动啊!!!!

n-type extrinsic, or p-type extrinsic? Why?

12.33 The following electrical characteristics have been determined for both intrinsic

and p

-type extrinsic indium phosphide (InP) at room temperature:

Calculate electron and hole mobilities.

12.34 Compare the temperature dependence of the conductivity for metals and

intrinsic semiconductors. Briefly explain the difference in behavior.

12.35 Using the data in Table 12.2, estimate the electrical conductivity of intrinsic

GaAs at 150C (423 K).

12.38 The intrinsic electrical conductivities of a semiconductor at 20 and 100C (293

and 373 K) are 1.0 and 500 (_-m)_1, respectively. Determine the approximate band gap energy for this material.

12.51 At temperatures between 775C (1048 K) and 1100C (1373 K), the activation

energy and preexponential for the diffusion coef- ficient of Fe2 in FeO are 102,000 J/mol and 7.3 _ 10_8 m2/s, respectively. Compute the mobility for an Fe2 ion at 1000C (1273 K).

12.52* A parallel-plate capacitor using a dielectric material having an r of 2.5 has a

plate spacing of 1 mm (0.04 in.). If another material having a dielectric constant of 4.0 is used and the capacitance is to be unchanged, what must be the new spacing between the plates?

12.54* Consider a parallel-plate capacitor having an area of 2500 mm2 and a plate

separation of 2 mm, and with a material of dielectric constant 4.0 positioned between the plates.

(a) What is the capacitance of this capacitor?

(b) Compute the electric field that must be applied for a charge of 8.0 _ 10_9 C to be stored on each plate.

12.55* In your own words, explain the mechanism by which charge storing capacity

is increased by the insertion of a dielectric material within the plates of a

capacitor.

12.59* (a) For each of the three types of polarization, briefly describe the mechanism

by which dipoles are induced and/or oriented by the action of an applied electric field. (b) For solid lead titanate (PbTiO3), gaseous neon, diamond, solid KCl, and liquid NH3 what kind(s) of polarization is (are) possible? Why?

17.1 Estimate the energy required to raise the temperature of 2 kg of the following

materials from 20 to 100_C aluminum, steel, soda–lime glass, and highdensity polyethylene.

17.3 (a) Determine the room temperature heat capacities at constant pressure for the

following materials: aluminum, silver, tungsten, and 70Cu-30Zn brass.

(b) How do these values compare with one another? How do you explain this? 17.4 For aluminum, the heat capacity at constant volume Cv at 30 K is 0.81 J/mol-K,

and the Debye temperature is 375 K. Estimate the specific heat (a) at 50 K and (b) at 425 K.

17.5 The constant A in Equation 17.2 is 12_4R/5 _3 D, where R is the gas constant

and_D is the Debye temperature (K). Estimate_D for copper, given that the specific heat is0.78 J/kg-K at 10 K.