南邮材料化学答案-第五章习题答案.doc

第五章 材料的制备
1. 提拉法中，控制晶体品质的因素主要有哪些？In the preparation of crystal with pulling method, what factors can influence the quality of crystal?
答：提拉法中，控制晶体品质的主要因素有固液界面的温度梯度、生长速率、转晶速率以及熔体的流体效应等。
Answer：In the preparation of crystal with pulling method, factors influence the quality of crystal include temperature gradient on solid-liquid interface, growth rate, crystal spin rate, and fluid effect of melt.
2. 单晶硅棒和厚度约1μm的薄膜分别可用什么方法制备？How to prepare Silicon rods and thick film about 1 μm ?
答：1）单晶硅棒可以用晶体生长技术中的提拉法来制备，即将硅原料熔体盛放在坩埚中，籽晶杆带着籽晶由上而下插入熔体，由于固液界面附近的熔体维持一定的过冷度，熔体沿籽晶结晶，以一定速度提拉并且逆时针旋转籽晶杆，随着籽晶的逐渐上升，生长成单晶硅棒。
2）厚度约1μm的单晶硅薄膜可用阴极溅射法制备，即利用高能粒子轰击固体靶材表面（Si），使得靶材表面的原子或原子团获得能量并逸出表面，然后在基片的表面沉积形成单晶硅薄膜。
Answer: 1) Silicon rods can be prepared by Czochralski crystal growth technology, that is to say, put the silicon raw material melt in the crucible and insert the seed rod with a seed crystal into the melt from top to bottom. Melt near the solid-liquid interface maintains a certain degree of supercooling, then the melt crystallize along the seed .Pull the seed rod at a certain speed and rotate it counterclockwise, with the gradual increase of the seed, grow into silicon rods.
2) Monocrystalline silicon thin film of 1μm thick can be prepared by cathode sputtering. Using energetic particle bombard the surface of the solid target (Si), and the target surface atoms or groups of atoms gain energy and escape from the surface, and then deposit on the surface of the substrate to form a monocrystalline silicon thin film.
3．液相外延法和气相沉积法都可制备薄膜，如果要制备纳米厚度的薄膜，应采用哪种方法？
Both liquid phase epitaxy method and vapor deposition can be used to prepair film, if you want to obtain film of nm thickness, which method should be selected?
答：液相外延法具有设备简单、纯度高的特点，但是由于晶体成核和生长的速率较快，得到的膜较厚，很难得到纳米厚度的薄膜。物理气相沉积可通过调控蒸镀源与靶之间的距离来调控膜沉积的速率，化学气相沉积可通过体系的温度、压力等因素来调控膜沉积的速率。因此，如果要制备纳米厚度的薄膜，应采用气相沉积法比较好。
Answer: Liquid phase epitaxy method is simple, and the purity of film is high, however, because the rate of nucleate formation and crystal growth is fast, it is difficult to get the membrane of nm thickness. For Physical vapor deposition, we can control the rate of film deposition through regulating the distance between the source and target. For chemical vapor deposition, we can control the film deposition rate by controlling temperature and pressure. So if you want to prepare film of nanometer thickness, vapor deposition should be selected.
4. CVD法沉积SiO2 可通过哪些反应实现？写出相关化学方程式。Which reactions can be used to deposite SiO2 with CVD? Write the relevant chemical equation.
答：CVD法沉积SiO2 可通过以下几种反应来实现。
1）烷氧化物的热分解：Si (OC2H5)4 → SiO2 + C2H4 + H2O
2）硅化合物的氧化反应：SiCl4 (g) + O2 (g) → SiO2 (s) + 2Cl 2 (g)
SiH4 (g) + O2 (g) → SiO2 (s) + 2H 2 (g)
SiCl4 (g) + 2CO2 + 2H 2(g) → SiO2 (s) + 4HCl (g) + 2CO (g)
3）硅化合物的水解反应：SiCl4 (g) + 2H2O (g) → SiO2 (s) + 4HCl (g)
Answer: CVD deposition of SiO2 can be achieved through the following reaction:
1) The alkoxide thermal decomposition: Si (OC2H5)4 → SiO2 + C2H4 + H2O
2) Oxidation of silicon compounds: SiCl4 (g) + O2 (g) → SiO2 (s) + 2Cl 2 (g)
SiH4 (g) + O2 (g) → SiO2 (s) + 2H 2 (g)
SiCl4 (g) + 2CO2 + 2H 2(g) → SiO2 (s) + 4HCl (g) + 2CO (g)
3) Hydrolysis of silicon compounds: SiCl4 (g) + 2H2O (g) → SiO2 (s) + 4HCl (g)
5. 用什么方法可以对Cu 和Cu2O进行分离？写出相关化学方程式。What method can be used for separation of Cu and Cu2O? Write the relevant chemical equation
答：对Cu 和Cu2O进行分离，可以采用化学气相输运技术，以HCl 作为输运气体。过程中发生如下反应：

由于从Cu2O生成CuCl为放热反应，而从Cu 生成CuCl为吸热反应，因此Cu2O在较高温度处沉积，而Cu 则在较低温度处沉积，从而可以对Cu 和Cu2O进行分离。
Answer: Cu and Cu2O can be separated by chemical vapor transport with HCl as the transport gas. The following reactions occur during the process：

Due to generation of CuCl from Cu2O is exothermic reaction, while generation of Cu from CuCl is endothermic reaction., Therefore Cu2O accumulate at higher temperature, while Cu accumulate at a relatively low temperature, thereby we can separate Cu and Cu2O.
6. 溶胶-凝胶法制备纤维材料，应采用怎样的条件较合适？请解释。Preparing fiber material by sol-gel, what conditions should be more appropriate? Please explain it.
答：溶胶－凝胶法制备纤维材料，应在拉纤阶段控制合适的粘度，选择合适的催化剂，选择合适的成纤方法。因为拉纤阶段溶胶的粘度会影响纤维的直径和纤维的质量，粘度大时得到的纤维直径较大，粘度小时得到的纤维直径较小。其次，因为是要得到纤维材料，所以缩聚的中间体应该是线形分子链，所以应使用酸催化，因为碱催化会得到三维网络结构的中间体。此外，如果要得到长纤维的话，可以用拉纤法，而要得到短纤维的话，应采用离心喷出法。
Answer: Preparing fiber materials by the sol-gel, appropriate viscosity should be controlled in order to choose a suitable catalyst and the right method to form the fiber in the tow stage. Because the sol's viscosity in the tow stage will affect the quality and diameter of the fiber, the diameter of fiber is bigger with high viscosity and smaller with low viscosity. Secondly, in order to get fiber materials, the intermediates of the polycondensation should be linear molecular chain, so acid catalysis should be used, due to alkali catalysis leading to three-dimensional network structure of the intermediate. In addition, if you want a long fiber, tow method should be used, while the centrifugal spray method should be used for short fiber.
7. 怎样用均匀沉淀法合成硫化锌颗粒？写出相关化学方程式。How to synthesize ZnS particles by homogeneous precipitation? Write the relevant chemical equation.

答：用均匀沉淀法合成ZnS颗粒，可以采用硫代乙酰胺（CH3CSNH3）作为硫源，以乙酸锌（（CH3COO）2 Zn） 为原料制得，反应方程式如下：

Answer: Synthesize ZnS particles by homogeneous precipitation method, thioacetamide (CH3CSNH3) can be used as a sulfur source and zinc acetate ((CH3COO) 2 Zn) can be used as raw materials, the reaction equation is as follows: