铁氮共掺杂制备TiO2及其蓝光下的光催化性能

用硝酸铁和盐酸羟胺分别作Fe源和N源,在TiO2溶胶中同时引入Fe和N,一步合成得到Fe、N共掺杂的纳米TiO2粉末。用XRD等技术研究了焙烧温度和N源量对其晶相结构的影响,并用低功率蓝光LED作光源测试其光催化性能。结果表明,400℃焙烧的Fe、N共掺杂TiO2粉末具有最好的催化性能,2h内对若丹明B的降解率达68.0%。增加N源量,有利于Fe在TiO2晶格中扩散,减小晶粒度;Fe、N共掺杂对TiO2的催化性能具有协同作用,其催化能力明显优于单掺杂样品;降解机理可能与紫外光源有所不同。     

阶梯栅氧结构的NLDMOS热载流子效应研究

本文对一种新型的阶梯栅氧结构的NLDMOS（Step Gate Oxide NLDMOS , SG-NLDMOS）的热载流子效应进行了研究。采用直流电压应力实验、TCAD仿真、电荷泵测试等方法,对退化现象进行了分析,并提出了退化机制。然后研究了漂移区注入剂量对器件热载流子效应的影响,结果表明低的漂移区注入剂量可以更有效地减小器件导通电阻的退化。     

Rational Designs for Lithium-Sulfur Batteries with Low Electrolyte/Sulfur Ratio

Lithium-sulfur batteries (LSBs) are considered a promising next-generation energy storage device owing to their high theoretical energy density. However, their overall performance is limited by several critical issues such as lithium polysulfide (PS) shuttles, low sulfur utilization, and unstable Li metal anodes. Despite recent huge progress, the electrolyte/sulfur ratio (E/S) used is usually very high (≥20 µL mg⁻¹), which greatly reduces the practical energy density of devices. To push forward LSBs from the lab to the industry, considerable attention is devoted to reducing E/S while ensuring the electrochemical performance. To date, however, few reviews have comprehensively elucidated the possible strategies to achieve that purpose. In this review, recent advances in low E/S cathodes and anodes based on the issues resulting from low E/S and the corresponding solutions are summarized. These will be beneficial for a systematic understanding of the rational design ideas and research trends of low E/S LSBs. In particular, three strategies are proposed for cathodes: preventing PS formation/aggregation to avoid inadequate dissolution, designing multifunctional macroporous networks to address incomplete infiltration, and utilizing an imprison strategy to relieve the adsorption dependence on specific surface area. Finally, the challenges and future prospects for low E/S LSBs are discussed.     

Thermal Annealing and Propagation of Shockley Stacking Faults in 4H-SiC PiN Diodes

Stacking faults within 4H-SiC PiN diodes are known to be detrimental to device operation. Here, we present electroluminescence (EL) images of 4H-SiC PiN diodes providing evidence that electrically and optically stimulated Shockley stacking fault (SSF) propagation is a reversible process at temperatures as low as 210°C. Optical beam induced current (OBIC) images taken following complete optical stressing of a PiN diode and that lead to a small number of completely propagated SSFs provide evidence that such defects propagate across the n–/p+ interface and continue to grow throughout the p+ layer. These observations bring about questions regarding the validity of the currently accepted driving force mechanism for SSF propagation.     

纳米BiVO_4的微波合成及其光催化性质

以五水硝酸铋和五氧化二钒为原料,通过微波合成法制备了纳米BiVO4,采用X-射线衍射(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)表征了样品的形貌、结构和特性。XRD表明所制备的样品是纯的单斜晶型BiVO4;SEM显示样品的形貌呈层状结构;TEM进一步指出这些片层结构是由小粒子聚集而成的多孔结构。以催化降解甲基橙来考察其光催化性能。在100mL的10mg/L甲基橙溶液中加入0.12g经673K恒温热处理2h后的BiVO4及0.2mL H2O2,调节pH值为3.0,在可见光下照射90min后,降解率达到94.70%,催化性能良好。     

Proportional degradation services in wireless/mobile adaptive multimedia networks

Adaptive multimedia services are very attractive since resources in wireless/mobile networks are relatively scarce and widely variable, and more importantly the resource fluctuation caused by mobility and channel fading can be mitigated using adaptive services. Therefore, there are extensive research activities on Quality of Service (QoS), call admission control, as well as bandwidth degradation and adaptation for adaptive multimedia services in wireless/mobile networks in recent years. However, fairness of bandwidth degradation has largely been ignored in previous work and remains an important issue in adaptive multimedia service provisioning. In this paper, we propose and study proportional degradation service provisioning in wireless/mobile networks that offer multiple classes of adaptive multimedia services. The proposed proportional degradation fairness model guarantees the proportional bandwidth degradation among different classes of services. Two proportional degradation scenarios are studied in this paper. In the first scenario, we study the proportional degradation provisioning with two QoS parameters for adaptive multimedia: the degradation ratio (DR) and the degradation degree (DD). In the second scenario, we study the proportional degradation provisioning with a new QoS parameter for adaptive multimedia: the degradation area (DA). For each scenario, based on the QoS parameters, proportional degradation adaptation algorithms are proposed to approximate the proportional degradation model, to fairly adapt calls' degradations, to utilize the system resource efficiently, as well as to optimize QoS parameters. Performance studies show that in the first scenario, proportional DR has been achieved very well, whereas proportional DD has not been well achieved. In other words, DR outperforms DD in terms of proportional degradation. In the second scenario, proportional DA has been well achieved. Furthermore, bandwidth resources have been efficiently utilized and DA has been minimized. Copyright © 2004 John Wiley & Sons, Ltd.     

PMN基铁电陶瓷电镀镍性能失效及恢复研究

针对铌镁酸铅（PMN）基弛豫铁电陶瓷电镀镍后性能失效行为,采用介温谱、绝缘电阻测量及高温退火方法进行了研究。实验表明,PMN基驰豫铁电镀镍后会出现介电常数下降、介质损耗和绝缘电阻增大,随电镀时间延长,试样失效程度增加。电镀失效试样经过500℃、2.5h空气退火后,性能完全恢复,分析认为,电镀过程中产生的活泼原子氢吸附在资体上,将瓷体中的某些金属元素还原,产生氧空位和自由电子,导致陶瓷电性能失效。而经过适当的氧化气氛退火后,失效试样被重新氧化,使得电性能恢复。     

PMOSFET's热载流子退化模拟及寿命评估的统一模型

对 PMOSFET's几种典型器件参数随应力时间的退化规律进行了深入研究 ,给出了一个新的器件退化监控量 ,并建立了不同器件参数退化的统一模型 .模拟结果和测量结果的比较表明 ,新的退化模型具有较高的准确性和较宽的适用范围 .新的退化模型不但可以用于器件参数退化量的模拟 ,也可以用于器件寿命评估     

基于紧缩阈值加速退化试验的长寿命产品可靠性评估

对于退化失效型产品,当产品的特性参数超过给定阈值时即发生失效,失效阈值定义越严格则对产品功能要求越高,则产品越容易发生因不满足该功能要求而失效,可见产品的寿命数据与失效阈值的定义密切相关.对于长寿命产品,通过紧缩失效阚值的方法,可以在低应力水平下得到更多的失效数据.论文建立了寿命分布与试验应力和失效阈值的关系模型,并提...     

基于性能退化的卫星用光纤陀螺可靠性评估

基于性能退化数据研究了卫星用光纤陀螺空间辐射环境下的可靠性评估方法.随着光纤陀螺技术水平的提高,其在卫星上的应用越来越广泛,其可靠性状况也愈发引起人们的关注.在对空间辐射环境下光纤陀螺失效机理分析的基础上,提出用Normal-Poisson复合随机过程模型对产品在空间辐射作用下的退化特性进行建模,基于所得模型,由光纤陀...