Influence of Precursor Powder Fabrication Methods on the Superconducting Properties of Bi-2223 Tapes

Bi-2223 precursor powders are prepared by both oxalate co-precipitation(CP) and spray pyrolysis(SP) methods.The influence of fabrication methods on the superconducting properties of Bi-2223 tapes are systematically studied. Compared to the CP method, SP powder exhibits spherical particle before calcination and smaller particle size after calcinations with more uniform chemical composition, which leads to a lower reaction temperature during calcination process for Bi-2223 tapes. Meanwhile, the non-superconducting phases in SP powder are more uniformly distributed with smaller particle sizes. These features result in finer homogeneity of critical current in large-length of Bi-2223 tape, higher density of filaments and better texture after heat treatment. Therefore,the SP method could be considered as a better route to prepare precursor powder for large-length Bi-2223 tape fabrication.     

Electrically Pumped Room-Temperature Pulsed InGaAsP-Si Hybrid Lasers Based on Metal Bonding

A pulsed InGaAsP-Si hybrid laser is fabricated using metal bonding. A novel structure in which the optical coupling and metal bonding areas are transversely separated is employed to integrate the silicon waveguide with an InGaAsP multi-quantum well distributed feedback structure. When electrically pumped at room temperature, the laser operates with a threshold current density of 2.9 kA/cm^2 and a slope efficiency of 0.02 W/A. The 1542nm laser output exits mainly from the Si waveguide.     

Investigation of SOI Substrates Incorporated with Buried MoSi2 for High Frequency SiGe HBTs

Highly arsenic-doped Si-on-insulator （SOI） substrate incorporated with buried MoSi2 layers is fabricated aiming at decreasing the collector series resistance of SiGe heterojunction bipolar transistors （HBTs） on SOI, thereby enhancing cutoff frequency （fT） performance and increasing the maximum value of fT （fTMAX ）. The .fT performance at medium current is enhanced and current required for fT = 15 GHz is reduced by half The value of fTMAX is improved by 30%.     

Growth of High Quality Strained-Si on Ultra-Thin SiGe-on-Insulator Substrate

Ultra-thin and near-fully relaxed SiCe substrate is fabricated using a modified Ce condensation technique, and then a 25-nm-thiek biaxially tensile strained-Si with a low rms roughness is epitaxially deposited on a SiGe- on-Insulator （SGOI） substrate by ultra high vacuum chemical vapor deposition （UHVCVD）. High-Resolution cross-sectional transmission electron microscope （HR-XTEM） observations reveal that the strained-Si/SiGe layer is dislocation-free and the atoms at the interface are well aligned. Furthermore, secondary ion mass spectrometry （SIMS） results show a sharp interface between layers and a uniform distribution of Ge in the SiCe layer. One percent in-plane tensile strain in the strained-Si layer is confirmed by ultraviolet （UV） Raman spectra, and the stress maintained even after a 30-s rapid thermal annealing （RTA） process at 1000℃. According to those results, devices based on strained-Si are expected to have a better performance than the conventional ones.     

收集方式对喷雾热分解Bi-2223 前驱粉末的影响

采用国产喷雾热分解设备制备了Bi-2223 前驱粉末, 分别选用一步收集和分级收集热分解后的粉末, 对不同方式收集的粉末进行了XRD 分析、SEM 观察以及ICP-AES 分析, 对比了粉末在相成份以及含量、 外观形貌、 粒径大小和元素原子配比等方面的差别, 最终发现采用一步收集方式采集的粉末在相组成、 成分均匀度以及原子配比方面均优于分级收集粉末, 一步收集方式更适合于收集Bi-2223 喷雾热分解粉末.     

喷雾热分解分级收集对Bi2223前驱粉末的影响

采用喷雾热分解方法制备了Bi-2223前驱粉末,对不同收集容器中的粉末进行了SEM观察、XRD分析、TG-DTA分析以及ICP-AES分析,对比了不同收集器中的粉末在外观形貌、粒径大小、相组成以及含量、成相反应以及元素原子配比等方面的差别。最终发现采用分级收集的方法制备的前驱粉,不同收集容器中粉末在粒径大小、相组成、成相行为以及元素原子配比方面差别明显,且两种收集器中粉末各元素原子实际配比与原始设计配比相比,发生严重偏离,导致最终制备的粉末不适合制备Bi-2223带材。     

Bi-2223/AgAu 带材及应用进展

Bi-2223/AgAu 高温超导带材因为较低的热导率和较高的载流性能, 被认为是制备高温超导电流引线的最佳材料之一. 这篇文章简单介绍了高温超导电流引线的工作特点和不同包套 Bi-2223 带材的热导率, 在此基础上详细介绍了目前 Bi-2223/AgAu 带材和高温超导电流引线国内外研究进展, 最后展望了 Bi-2223 带材的发展趋势.