材料物理性能习题缺热电学英文版

材料物理性能习题

目录

材料物理性能习题........................................................................................... 错误!未定义书签。电介质 .............................................................................................................. 错误!未定义书签。光学 .................................................................................................................. 错误!未定义书签。磁学 .................................................................................................................. 错误!未定义书签。

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，其在1kHz下的相对介电常数为。

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.

3．Ionic 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 nm. The electronic polarizability of Cs+ and Br- ions are 10-40 F m2 and 10-40 F m2, respectively, and the mean ionic polarizability per ion pair is 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 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

提示:查材料的介电性能的参考书,并且在作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 .

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s =10, ∞=2, =10-10s ，请分别画出’、’’以及tanδ随lgω变化曲线，在曲线上标出tanδ和’’峰值的位置， ’’ 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，

（a ）求对于n1(空气）=1和n2(Si)=的反射系数。

（b ） 查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,,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 laser windows), lenses, prisms etc. It transmits over to 19 μm. n in the 1 – 11 μm range described by a Cauchy expression of the form

24200030006100485043652λ. λ.λ..n -++= in which λ 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分别是和，求能够在光钎中传播的入射光与钎轴向的夹角最大是多少

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.

r r n με=