Solar-driven high-temperature steam generation at ambient pressure

This paper demonstrates a facile solar steam generator for the generation of high-temperature steam at ambient pressure. The steam generator consists of a coiled copper tube(CCT) that serves as both solar collector and vapor heater. Both the inner and outer surfaces of the CCT are coated with black superhydrophobic copper oxide layer to improve the solar absorption, and such superhydrophobic layer prevents the condensation and clogging of water vapor during the heating process. Solar vapor is generated at the inlet of CCT through interfacial evaporation and subsequently heated inside the CCT as the vapor travels from the inlet to the outlet. By employing this approach, steam temperature that exceeds 100℃ under 1-sun illumination is demonstrated. Furthermore,steam temperature could reach as high as 250℃ under 10-sun illumination at ambient pressure. Successful sterilization experiment was also performed in this work to demonstrate the potential application of the high temperature steam generated. Such demonstrated approach helps open up the potential usage of solar-driven interfacial evaporation in applications that involve high-temperature steam, including medical sterilization,chemical manufacturing and food processing.     

Superconductivity in lithium below 0.4 millikelvin at ambient pressure

Elements in the alkali metal series are regarded as unlikely superconductors because of their monovalent character. A superconducting transition temperature as high as 20 K, recently found in compressed lithium (the lightest alkali element), probably arises from pressure-induced changes in the conduction-electron band structure. Superconductivity at ambient pressure in lithium has hitherto remained unresolved, both theoretically and experimentally. Here we demonstrate that lithium is a superconductor at ambient pressure with a transition temperature of 0.4 mK. As lithium has a particularly simple conduction electron system, it represents an important case for any attempts to classify superconductors and transition temperatures, especially to determine if any non-magnetic configuration can exclude superconductivity down to zero temperature. Furthermore, the combination of extremely weak superconductivity and relatively strong nuclear magnetism in lithium would clearly lead to mutual competition between these two ordering phenomena under suitably prepared conditions.     

晶体硅太阳电池弱光下的开路电压

本文讨论了弱光下影响晶体硅太阳电池的开路电压的主要因素,得出要提高弱光下的开路电压应主阳电池的并联电阻电阻。     

碳化硅陶瓷的放电等离子烧结

采用添加了Al2O3和Y2O3助烧剂的碳化硅微粉为原料,通过放电等离子烧结(SPS)技术快速制备了碳化硅陶瓷. 分析了材料致密化过程,并重点研究了烧结工艺参数对材料致密度和力学性能的影响规律. 结果表明,当SPS工艺参数的烧结温度和压力分别为1600℃和50MPa时,经过5min的烧结,碳化硅陶瓷的致密度可达到99.1%,硬度为HV 2550,断裂韧性达8.34MPa·m1/2,弯曲强度达684MPa.     

干燥溶剂介质对常压制备SiO2气凝胶的影响

以正硅酸乙酯和乙醇等为原料,通过溶胶-凝胶、表面修饰及溶剂置换等后续工艺,实现常压干燥法制备块状SiO2气凝胶,并考察干燥溶剂介质对气凝胶常压制备的影响。研究结果表明:采用混合溶剂干燥的SiO2气凝胶性能较单一溶剂更佳,以正己烷和甲苯混合溶剂制备的SiO2气凝胶性能最优,具有低表观密度(0.102 7 g/cm3)、高比表面积(928.4 m2/g)、大孔容(3.295 cm3/g)及疏水性良好等特性。     

室温常压溶液法合成烯丙基功能化的正六边形硅纳米晶体

室温常压下,以氢化铝锂为还原剂在溶液中还原烯丙基三氯硅烷和四氯化硅体系,制备了烯丙基功能基团修饰的正六边形硅单晶.采用透射电子显微镜（Transmission Electron Microscopy,TEM）和傅里叶变换红外光谱（Fourier Transform Infrared,FTIR）对产物进行表征.研究了硅晶体的尺寸分布、晶面取向及表面组成,推测了可能的反应机理.结果表明,三氯硅烷与四氯化硅浓度比为1：3时经过还原可生成尺寸为20~50nm,表面有烯丙基基团的（111）晶向的单晶硅.     

多热源合成SiC传热规律

对多热源合成SiC冶炼炉的温度场进行了数值模拟,研究了冶炼炉内的温度分布、热流强度以及温度梯度的动态变化规律,揭示了多热源合成SiC的传热传质规律.研究表明,由于多热源之间的屏蔽作用与热能叠加作用,导致多热源合成SiC技术比Acheson单热源炉的单炉产量提高48.1%,特、一级品率提高30%,节能10%以上,并且杜绝了单热源生产中频繁喷炉事故,使生产更安全.     

强电离放电合成氨实验研究

针对国内外低气压等离子体合成氨浓度偏低的现状,利用常温常压下应用强电离放电在反应腔内产生的强烈放电将N2、H2电离、离解, 获得大量的自由原子、离子、自由基等活性粒子,在定向化学反应模型的控制下合成NH3.讨论了气体总流量、N2/H2体积比、气体温度、放电的折合电场强度等参数对合成氨浓度的影响,合成氨最高的体积分数达12 500×10-6.     

抗坏血酸在钼蓝法测定微量SiO_2中的应用

研究了以抗坏血酸为还原剂 ,用光度法测定碳化硅超细粉中微量SiO2 (硅钼蓝 )的方法 .结果表明 ,最大吸收波长为 80 0nm ,表观摩尔吸光系数为 2 .5 0× 10 4 L/ (mol·cm) ,线性范围为 0 .0 5～ 0 .0 7mg/L ,平均回收率为 99.32 % ,RSD为 1.6 7% ,该法适用于碳化硅超细粉中微量SiO2 的测定 .     

晶体硅太阳电池表面钝化的研究

文章从理论上分析了太阳电池的表面复合及重掺杂效应。在实验上采用二氧化硅作为钝化膜,比较了两种不同表面浓度的太阳电池片钝化效果,得出低表面浓度的太阳电池片比高表面浓度的太阳电池片的开路电压要高,短波光谱响应要好。开路电压和短波光谱响应的提高主要来自于前表面的钝化和适当地降低了表面浓度。     

粉末材料常温压制成型残余应力分布研究

研究并给出了自制压力传感器的设计原理及性能指标、利用自行设计的传感器,预埋在用细质土模的粉末材料中,测在常温下成型过程中加、卸载时压坯内的应力分布,重点研究对成型后的残余应力分布的影响,得出了材料成型过程中残余应力分布规律和裂纹成因,解决了粉末材料成型开裂问题,实践证明自行设计的传感器稳定性能好,适应性强。     

纳米结构碳化钽在超高压力下硬度的研究

通过利用国产DS6×800T铰链式六面顶压机装置高温高压烧结了纳米结构的碳化钽样品,研究和表征了纳米结构碳化钽在超高压力下的物性行为。样品在3 GPa/1 500℃下进行烧结,其相对密度为93%。实验结果表明超高压力更有利于样品的致密化,并且可以降低烧结温度。通过烧结实验,得到了纳米结构碳化钽在压力为3 GPa时的维氏硬度为17.2 GPa,平均断裂韧度为(5.0±0.2)MPa m1/2。     

影响SiC泡沫陶瓷浆料性能的主要因素研究

通过对碳化硅水基浆料相对沉降高度的测量及不同实验条件下浆料粘度的测定,研究了添加剂用量、固相含量及剪切速率对碳化硅泡沫陶瓷用水基浆料稳定性、触变性及粘度的影响。结果表明,浆料的粘度随剪切速率增加而减小,随固相含量增大而增大,而且具有明显的时间依附性。添加剂PAM的最佳质量分数为0.08%,固相含量在62%左右,浆料的稳定性、触变性较优。     

强电离放电常压离子注入乙酸钠

利用介质阻挡强电离放电的物理方法,在窄放电间隙内获得超强电场,在常压下将N2分子电离、离解,形成N2^ 、N^ 等离子,注入乙酸钠样品,引起其分子结构的变化．通过水合茚三酮反应分析,证明了离子注入后乙酸钠样品中产生了新的化学基团α—NH2．同时紫外光谱的分析进一步证实乙酸钠样品在离子注入后发生了明显的分子结构变化．     

Room temperature coherent control of defect spin qubits in silicon carbide

Electronic spins in semiconductors have been used extensively to explore the limits of external control over quantum mechanical phenomena. A long-standing goal of this research has been to identify or develop robust quantum systems that can be easily manipulated, for future use in advanced information and communication technologies. Recently, a point defect in diamond known as the nitrogen-vacancy centre has attracted a great deal of interest because it possesses an atomic-scale electronic spin state that can be used as an individually addressable, solid-state quantum bit (qubit), even at room temperature. These exceptional quantum properties have motivated efforts to identify similar defects in other semiconductors, as they may offer an expanded range of functionality not available to the diamond nitrogen-vacancy centre. Notably, several defects in silicon carbide (SiC) have been suggested as good candidates for exploration, owing to a combination of computational predictions and magnetic resonance data. Here we demonstrate that several defect spin states in the 4H polytype of SiC (4H-SiC) can be optically addressed and coherently controlled in the time domain at temperatures ranging from 20 to 300 kelvin. Using optical and microwave techniques similar to those used with diamond nitrogen-vacancy qubits, we study the spin-1 ground state of each of four inequivalent forms of the neutral carbon-silicon divacancy, as well as a pair of defect spin states of unidentified origin. These defects are optically active near telecommunication wavelengths, and are found in a host material for which there already exist industrial-scale crystal growth and advanced microfabrication techniques. In addition, they possess desirable spin coherence properties that are comparable to those of the diamond nitrogen-vacancy centre. This makes them promising candidates for various photonic, spintronic and quantum information applications that merge quantum degrees of freedom with classical electronic and optical technologies.     

硅集成压力传感器设计

主要对硅集成传感器的理论设计进行了分析和探讨。     

稀土氧化物对碳化硅晶须形成的影响

研究了氩气气氛下稀土氧化物对不同碳源形成SiC晶须的影响.结果表明,稀土氧化物能够在一定程度上促进碳化硅晶须的形成.稀土氧化物能够改变碳化硅晶须的形貌,主要表现在提高碳化硅晶须的直晶率和直径.不同种类的稀土氧化物,其催化效果不同.     

微细塑性铣削单晶硅实验研究

为了深入探讨塑性铣削单晶硅的切削机理,对单晶硅进行了微细铣削实验研究.结果表明,合理地设定铣削参数与保证特定的铣削环境都很重要,在这个前提下,可以实现塑性切削,在单晶硅上获得具有完整几何外形的特征,同时表面质量可以达到单纳米级别.     

围压对旋转射流破岩钻孔效率的影响

根据现场径向水平钻井技术的需要 ,在前期常压条件下研究的基础上 ,对围压条件下旋转射流的破岩钻孔效率进行了试验研究。结果表明 ,在围压条件下 ,随着射流压力的增加 ,旋转射流破岩效率呈现出线性增加的趋势。随着喷距的增加 ,破碎效率呈现出先增加后减小的趋势 ,即存在最优喷距。在围压低于 5MPa时 ,破碎红砂岩的最优无因次喷距为 2～ 2 .5 ;随着围压的增加 ,破岩效率呈指数下降趋势 ,最优喷距随围压的增加而减小。在同压差条件下 ,围压比射流压力对破碎效果的影响更大。