Effects of annealing processes on Cu<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Si<Subscript>1-<Emphasis Type="Italic">x</Emphasis></Subscript> thin films

The Cu _x Si_1-x thin films have been grown by pulsed laser deposition (PLD) with in situ annealing on Si (001) and Si (111), respectively. The transformation of phase was detected by X-ray diffraction (XRD). The results showed that the as-deposited films were composed of Cu on both Si (001) and Si (111). The annealed thin films consisted of Cu + η”-Cu₃Si on Si (001) while Cu + η’-Cu₃Si on Si (111), respectively, at annealed temperature (T _a) = 300-600 °C. With the further increasing of T _a, at T _a= 700 °C, there was only one main phase, η”-Cu₃Si on Si (001) while η’-Cu₃Si on Si (111), respectively. The annealed thin films transformed from continuous dense structure to scattered-grain morphology with increasing T _a detected by field emission scanning electron microscope (FESEM). It was also showed that the grain size would enlarge with increasing annealing time (t _a).     

化学气相沉积生长氧化铪薄膜研究进展

氧化铪薄膜具有高介电常数、大击穿场强、高热稳定性、高力学强度等优势,是新一代高集成芯片中的理想介质材料。本文总结了氧化铪薄膜的主要特性、制备技术及在芯片介质层中的应用。针对芯片介质层的电、热、力学性能与生产要求,以氧化铪薄膜制备技术的发展历程为主线,重点介绍各类化学气相沉积方法的特点与典型研究成果,讨论了氧化铪薄膜制备技术存在的问题,并对该领域未来的发展趋势进行了展望。     

Enhanced Thermoelectric Performance of Non-equilibrium Synthesized Fe_(0.4)Co_(3.6)Sb_(12-x)Ge_x Skutterudites via Randomly Distributed Multi-scaled Impurity Dots

The p-type Ge doped Fe_(0.4)Co_(3.6)Sb_(12-x)Ge_x skutterudites with multi-scaled impurity dots(500 nm-2 mm) were successfully prepared by using melt-quenching(MQ) and subsequent spark plasma sintering(SPS) technique. Compared with traditional method, the new technology significantly shortened the processing time from several days to less than 24 hours. The phase of impurity dots was demonstrated to be CoSb through analysis of X-ray diffraction(XRD) and energy-dispersive spectrum(EDS). Impurity dots were induced by Ge substitution of Sb in the non-equilibrium synthesized process. Due to the abandonment of the long reaction of annealing crystallization, a few of Ge atoms would fail to substitute Sb site of skutterudite in this non-equilibrium synthesized process, leading to that the multi-scaled impurity dots randomly distributed in the matrix of skutterudite Fe_(0.4)Co_(3.6)Sb_(12-x)Ge_x. The combination of multi-scaled impurity dots scattering long wavelength heat-carrying phonons and the point defect scattering short and middle wavelength heat-carrying phonons dramatically made the 22.2% reduction of lattice thermal conductivity. As a result, compared with unsubstituted sample of Fe_(0.4)Co_(3.6)Sb_(12), the maximum ZT value was increased by 30.5%. Thus, the two marked features of this new synthesis process, the shortened preparation time and the enhanced thermoelectric performance, would make a promising commercial application in the future.     

客车空调压缩机排气管路失效分析与结构改进

采用ANSYS Workbench软件对客车空调压缩机排气管路进行失效分析和结构改进。以3种典型管路为研究对象,在压缩机端施加位移载荷进行管路失效分析,模拟结果与管路实际断裂位置一致。通过添加弯头、调整管路角度以及增加不锈钢波纹管长度等改进措施,可以降低管路的最大等效应力,延长管路的使用寿命。     

硼碳氮薄膜的脉冲激光沉积及其光学性能

采用脉冲激光沉积技术,在Si(100)和石英基片上制备了硼碳氮薄膜(BCN)。利用X射线衍射(XRD),傅里叶变换红外光谱(FTIR)、X射线光电子能谱(XPS)和紫外-可见分光光度计对BCN薄膜进行了表征,研究了激光能量密度对BCN薄膜沉积速率、组分、结构和光学性能的影响。FTIR和XPS分析结果表明BCN薄膜中包含B-C,C-N和N-B化学键,说明实现了B、C和N的原子级化合。当激光能量密度从1 J/cm2增加到6 J/cm2时,BCN薄膜的沉积速率加快,N含量由7.2%增加到15%,光学禁带宽度(Eg)从4.02 eV降低到3.82 eV,Eg的降低主要与BCN薄膜中碳含量的增加有关。     

自模板法合成银纳米碗

采用自模板法合成了碗状银纳米材料,研究了银纳米碗的结构和生长机理。结果表明：AgNO₃和NaOH反应生成Ag₂O纳米簇,然后加入还原剂甲醛,在Ag₂O模板表面形成Ag纳米壳,副产物CO₂则在Ag壳内聚集。随着反应的进行,不断增大的压力最终击穿Ag壳,形成了直径约为200 nm的Ag纳米碗。该方法为特殊结构贵金属纳米材料的研究提供了理论和实验基础。     

Preparation of layered potassium titanate whiskers with large length-diameter ratio by KDC method

Pure K2Ti4O9 whiskers were prepared by KDC(Kneading-Drying-Calcination) method with TiO2 and K2CO3 as raw materials. The influences of TiO2/K2CO3 molar ratio(RT/K), calcination temperature(TC) and cooling process on phase composition and morphology of the whiskers were investigated by TG-DSC(thermo gravimetric-differential scanning calorimeter), XRD(X-ray diffraction), and SEM(scanning electron microscope). Pure K2Ti4O9 potassium titanate whiskers with large length-diameter ratio(r)(over 250) can be obtained at RT/K = 2.9 and TC = 950 ℃.     

沉积温度和退火处理对BCN薄膜结构的影响

采用脉冲激光沉积技术,在Si(100)基片上制备了BCN薄膜,研究了沉积温度和退火处理对BCN薄膜组分和结构的影响。利用傅里叶变换红外光谱(FTIR)和X射线光电子能谱(XPS)对制备的BCN薄膜进行了表征。结果表明:沉积温度升高时,BCN薄膜的组分无明显改变。所制备的BCN薄膜包含B—N,C—B和C—N化学键,是由杂化的B—C—N键构成的化合物。真空退火温度为700℃时,BCN薄膜结构稳定;大气退火温度达到600℃时,BCN薄膜表面发生氧化分解,同时有C≡N键形成,表明C≡N键具有较好的高温热稳定性。     

钐掺杂对锰基催化剂的NO分解性能影响

采用共沉淀法,以乙酸锰为前体,pH为10,焙烧温度为700℃时,制备得到不同含量钐元素（Sm）掺杂锰基催化剂,研究Sm掺杂对催化剂物相、形貌、比表面积及NO催化转化能力的影响。结果表明：Sm掺杂有利于活性物质MnO₂的生成,Sm/Mn摩尔比为0.05时,锰基催化剂在100~700℃的整个温度窗口内,NO的转化率都较高,且在温度高于150℃时NO转化率超过80%。钐嵌入锰晶格形成钐锰固溶体,三价钐取代四价锰,在催化剂中形成阴离子空位,产生缺陷,表面缺陷位增多使得活性位点增加,促进了催化反应。     

增材制造压电陶瓷的现状与展望

压电陶瓷作为一类重要的功能陶瓷材料, 具备高强度、高硬度、耐腐蚀等优点, 可实现机械能和电能间的相互转换, 常被用于制备传感器、驱动器、电容器等压电器件, 在海洋探测、生物医疗、电子通讯等高端装备中发挥着重要作用。针对高端技术领域对压电功能器件智能化、集成化、轻量化的发展需求, 压电陶瓷的外形和结构越来越复杂。注浆、注射、模压、切割等传统的压电陶瓷制造工艺, 大多需借助模具或刀具完成, 很难甚至无法制造具有中空、悬垂等复杂结构的压电陶瓷, 制约了压电功能器件的进一步发展。增材制造技术基于逐层累加原理可实现任意复杂结构快速定制, 具有成型效率高、无需模具等优点, 可满足个性化、整体化、复杂化制造需求, 近年来受到国内外压电陶瓷领域研究人员的广泛关注。本文从粉体、浆料、块材三种原材料形态角度, 综述了当前增材制造压电陶瓷的主要工艺种类及发展现状, 综合对比了各种工艺成型特点; 介绍了增材制造压电陶瓷在不同领域的应用进展; 最后, 总结和展望了增材制造压电陶瓷所面临的挑战和未来可能的发展趋势。