材料物理性能习题缺热电学英文

1、材料物理性能习题目录材料物理性能习题1电介质1光学2磁学3电介质1 Briefly explain how the charge storing capacity of a capacitor may be increased by the insertion and polarization of a dielectric material between its plates.2 非晶态硒是一种高电阻率的半导体，其密度约为4.3g/cm-3，原子序数为34，相对原子量为78.96，其在1kHz下的相对介电常数为6.7。计算施加在每个原子上的局部电场Eloc相对宏观电场E的大小。局部场大还是

2、外加电场大?如果设局部电场等于外加电场,请给出克劳修斯-莫索蒂方程的表达式.3Ionic and electronic polarization Consider a CsBr crystal that has the CsCl unit cell crystal structure (one Cs+-Br- pair per unit cell) with a lattice parameter (a) of 0.430 nm. The electronic polarizability of Cs+ and Br- ions are 3.35 ´ 10-40 F m2 and 4

3、.5 ´ 10-40 F m2, respectively, and the mean ionic polarizability per ion pair is 5.8 ´ 10-40 F m2. What is the low frequency dielectric constant and that at optical frequencies? Is the dielectric constant in low frequency and optical frequency the same? Why？4. (a) For each of the three typ

4、es 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? 提示:查材料的介电性能的参考书,并且在作

5、业中写出所查参考书名字,页数. 5.查文献,描述偶极子转向极化的过程(参照课堂上给出的热离子松弛极化描述过程：没有加电场的状态，加电场后的运动过程，最后的状态)orientation polarization, is found only in substances that possess permanent dipole moments. Polarization results from a rotation of the permanent moments into the direction of the applied field, as represented in Figure

6、 18.32c. This alignment tendency is counteracted by the thermal vibrations of the atoms, such that polarization decreases with increasing temperature.Response of permanent electric dipoles (arrows) to an applied electric field, producing orientation polarization.6根据德拜方程，查阅资料，说明频率、温度对介电常数的实部、虚部和损耗角正切

7、的影响。7.限本章教学内容范围,提出一个自己不懂的问题8.思考题(选作)结合材科基课程中玻璃的结构知识,查文献,举例说明引起结构损耗以及中和效应的原因的具体来源 某介质的es=10, e=2, t=10-10s，请分别画出e、e以及tan随lg变化曲线，在曲线上标出tan和e峰值的位置， e max等于多少？光学1 太阳能电池中的增透膜： 当光照射到半导体表面时，光被部分反射。在太阳能电池中，进入半导体器件中的透射光能量被转换为电能。所以被部分反射的光是需要重点考虑的因素。波长700-800nm附近的硅的折射率约为3.5，（a）求对于n1(空气）=1和n2(Si)=3.5的反射系数。（b） 查

8、资料寻找用于降低在硅和空气之间的反射率的增透膜材料和使用了增透膜之后的反射率.2.已知折射率 ,折射率随介电常数增大而增大,根据已经学习的电介质材料性能,从介电常数和材料结构的关系角度,简单说明折射率和材料结构的关系3. Cauchy dispersion relation for zinc selenide ZnSe is a II-VI semiconductor and a very useful optical material used in various applications such as optical windows (especially high power las

9、er windows), lenses, prisms etc. It transmits over 0.50 to 19 µm. n in the 1 11 µm range described by a Cauchy expression of the formin which is in µm. What is ZnSe's refractive index n at 5 µm and 8µm?4.有一光钎的钎芯和包层的折射率分别为n1和n2，n1和n2分别是1.455和1.440，求能够在光钎中传播的入射光与钎轴向的夹角最大是多

10、少？ 查出一种已经商用化的通讯用光纤的以下资料: 名称，型号，钎芯和包层的折射率;目前传导的光的波长是多少? 制备光纤的材料,衰减特性，造成光纤传导衰减的原因.5.Gallium arsenide (GaAs) and gallium phosphide (GaP) are compound semiconductors that have room-temperature band gap energies of 1.42 and 2.25 eV, respectively, and form solid solutions in all proportions. Furthermore,

11、the band gap of the alloy increases approximately linearly with GaP additions (in mol%). Alloys of these two materials are used for light-emitting diodes wherein light is generated by conduction-band-to-valence-band electron transitions. Determine the composition of a GaAsGaP alloy that will emit or

12、ange light having a wavelength of 0.60m. 6.查资料,以一个具体材料为例,简单说明利用拉曼散射鉴别材料微结构的原理7.查资料说明用异质结来增加LED器件输出光强度的原理.8. 就本章教学内容,提出一个自己不懂的问题9.解答电介质一章同学提出的问题磁学1.Briefly explain the nature and source of (a) diamagnetism, (b) paramagnetism, and (c) ferromagnetism. 2. Compute the atomic magnetic moments of the rare

13、earth Nd metal and metal Co。3. Compute the molecular magnetic moment of CoFe2O4 ferrite，Its magnetic structure is: (Fe3+)Co2+Fe3+O44. Compute Bohr magnetons associated with each iron atom, given that the saturation magnetic polarization is 2.2T(J=m0M). The density of iron is 7.87g/cm3.5. Briefly exp

14、lain why the magnitude of the saturation magnetization decreases with increasing temperature for ferromagnetic materials, and why ferromagnetic behavior ceases above the Curie temperature.6. Explain a difference of the magnetization curves of the polycrystalline magnetic bar in figure 2.1 when the m

15、agnetic field was applied at different direction。7.查资料，简述一种利用控制成分或者结构降低磁性材料磁晶各向异性的方法。8已知单位体积铁磁性材料的退磁能可以写成：求有如下体积的单晶铁的退磁能：(a)具有单畴的1*1*1cm3块体以及直径为1*10-9m的小球9。利用表3-6，计算直径为1*10-9m的小球中存在图3-32(a)的磁畴时的畴壁能大小。比较第8题和第9题结果，你认为直径为1*10-9m的小球实际存在的磁畴结构是单畴还是如图3-32(a) 那样的畴？10. What kind of the magnetic domain config

16、uration may forms for iron and cobalt metal balls in figure 8 if only the magnetocrystalline anisotropy is considered? Fig.811。The following data are for a transformer steel:(a) Construct a graph of B versus H.(b) What is the value of the maximum permeability?(c) At about what H field does this maxi

17、mum permeability occur?(d) To what magnetic susceptibility does this maximum permeability correspond?12. 根据给定的H-Bdata中的数据，把H的单位换成Oe,计算: （1）做H-B图； （2）求出Br,Hc,Bs值，并且标在图上； （3）求H-B曲线第二象限的BH值，并做H-BH图，求出(BH)max,在图上标出该点。 （4）结合教科书和查资料,叙述如何提高Br,Hc?13. (a) Describe magnetic hysteresis; (b) explain why ferromagnetic and ferrimagnetic mater