1.Explain two types of defects created in crystalline ionic solida (1)Schottky defects and (2)Frenkel defects.(10) [solution] Schottky defect: 是晶体结构中的一种因原子或离子离开原来所在的格点位 置而形成的空位式的点缺陷。在离子晶体中，各种离子形成的肖特基缺陷数 目符合晶体的元素构成比例，因为只有这样形成缺陷後的晶体才是电中性的。 Frenkel defect: 是指晶体结构中由於原先占据一个格点的原子（或离子）离 开格点位置，成为间隙原子（或离子），并在其原先占据的格点处留下一个空 位，这样的空位-间隙对就称为弗仑克尔缺陷。 2.(习题57题)The band gap in aluminum phosphide(AlP) is 2.5 electron-volts(the charge of electon is 1.6*10^-19 Coulomb). What wavelength of light is emitted by an AlP diode?(10) 3.(习题51题)A. Use the band model to explain how conductors and seminconductors differ as to the effect of temperature on electrical conductivity.(10) B. Using silicon seminconductors as a model, define the n-type and p-type seminconductors.(10) 10.The standard enthalpy of combustion of cyclopropane is -2091 KJ/mol. The standard enthalpy of formation for CO2(g) and H2O(l) is -393.51 and -285.83 KJ/mol, respectively. Calculate the enthalpy of formation of cyclopropane to be (a)53KJ/mol,(b)42KJ/mol,(c)102KJ/mol,(d)33KJ/mol,(e)none of above 16.Diesel fuel normally uses petroleum of (a)C5-C10,(b)C10-C18,(c)C15-C25,(d) >C25,(e)cannot be determined 1.Li(s) → Li(g) heat of sublimation of Li(s)=166 KJ/mol HCl(g) → H(g) + Cl(g) bond energy of HCl=427 KJ/mol Li(g) → Li(g)+ + e- ionization energy of Li(g)=520 KJ/mol Cl(g) + e- → Cl-(g) electron affinity of Cl=-349 KJ/mol Li(g)+ + Cl-(g) → LiCl(s) lattice energy of LiCl(s)=-829 KJ/mol H2(g) → 2H(g) bond energy of H2(g)=432 KJ/mol Calculate the net change in energy for the reaction: 2Li(g) + 2HCl(g) → 2LiCl(s) + H2(g) a)363 KJ b)-562 KJ c)-179 KJ d)-73 KJ e)non of above e.n-type and p-type of semiconductors.(5%) What type of semiconductor would be formed if a small amount of Selenium impurity were added to pure Arsenic? 3.For a given volume, which of the following shapes has the smallest surface (a)cube (b)tetrahedron (c)pyramid (d)octahedral (e)sphere 4.Which method may generally decrease the conductivity of a semiconductor (a)decreasing the temperature (b)adding an impurity (c)irradiating with (d)decreasing the energy gap (e)none of tghe answers 11. describe the free electron model (classical model) and quantum mechanical model for the metal conductivity (5). What is the drawback(缺点) of the classical model?(5) 12. (a) Using the band gap theory to explain the semiconductor, (b)p-type semiconductor, (c) n-type semiconductor. (3 points each) B-3. (习题 chapter 16-51 衍生) (a)Using the band gap theory to explain the insulator, conductor, semiconductor, p-type semiconductor and n-type semmiconductor. (10) (b)Upon increasing temperature, predict the trend of conductivity (increase of decreade) of conductor and semiconductor.Explain. (5) sol> 图略 如果几个原子集合成分子，这会产生与原子数量成比例的分子轨道。当大量 （数量级为10^20或更多）的原子集合成固体时，轨道数量急剧增多，轨道相互 间的能量的差别变的非常小。形成所谓的band。 物质的导电性决定於价带与传导带之间的能量差，也就是所谓的band gap。 band gap越小则导电性越大。金属没有band gap；半导体的band gap大约为 1.1 eV；绝缘体则有相当大的band gap。 (p-type 和 n-type 从略) 金属的导电性随着温度上升而下降，因为温度的上升会导致金属阳离子振动的增 加，阻碍自由电子的运动。在半导体中，温度的上升导致一些电子从价带被激发 到传导带，使得价带中有电洞而传导带中有自由电子，因此导电性上升。 13. Based on the p-n junction, describing the photovoltaic cell.(3) B-1-4. What does state function mean? (5) Which of the following functions are state functions:(a)PV work,(b)heat,(c)entropy,(d)free energy (e)electrical work. (5) B-2. Silver crystallizes in a cubic closest packed structure shown below.The radius of a silver atom is 1.44埃, calculate the density of solid silver.(molecular weight of silver = 107.9 g/mol) (10) ( 图为一cubic closest packed structure ) sol> Mass 4×107.9(g/mol)/(6.02×10^23)(1/mol) D = ──── = ────────────────── = 10.6 g/cm^3 Volume [4(1.44×10^(-8))(cm)/√(2)]^3 B-1-2. First, Second and Third law of thermodynamics. (5) sol> First: 能量在各型式间转换时不灭 Second: 系统所吸收的热无法完全转换为功, or 自发反应的发生必伴随着乱度的增加 Third: 完美晶体在绝对零度时的乱度为0 1-5 Explain why the molar heat capacity (Cv) of most mono atomic metal is ~3R at room temperature (Pierre-Louis Dulong and Alexis-Therese Petit rule), while Cv is ~0 when temperature is close to 0 K.(5) B1-1.Using the band gap theory to explain the "conductor", "semiconductor", "p- type conductor", "n-type conductor". (10) B-1-4. What does state function mean? [sol]State function: 处於平衡态的热力学系统，各宏观物理量具有确定的值，并 且这些物理量仅由系统所处的状态所决定，与达到平衡态的过程无关，因此被 称之为状态函数。 B1-7. What does state function mean?(5) Which of the following functions are state functions (复选, multiple choices): (a) work, (b) internal energy, (c) heat, (d) temperature, (e) gravitational potential, (f) free energy, (g) f(x,y)=xy+6x2+y^2-2x+3y (5) B2. Cubic packing spheres are stacked on top of each other in successive layers. Define volume occupied by spheres in the unit cell f_v = ─────────────────────── volume of the unit cell prove f_v = 52.4% for a cubic packing.(10) 上面都是冗ㄐㄐㄐㄐㄐㄐㄐㄐㄐㄐㄐ在九如冗时收集的考古题 可能会在下次的小考出现~ --

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