纳米氧化镱对熔融石英析晶动力学机制的影响

本文研究引入纳米氧化镱对熔融石英析晶机制及动力学过程的影响.通过X射线衍射仪(XRD)测试结果分析了纳米氧化镱的引入对熔融石英陶瓷析晶率的影响,采用动力学方法分析了纳米氧化镱的引入对熔融石英陶瓷析晶机制的影响,同时探讨了其等温析晶动力学过程.研究表明,熔融石英陶瓷的晶粒向二维兼有一维及三维的方式生长,引入纳米氧化镱的熔...     

多级结构SiC纤维制备及电化学性能研究

鉴于中空和表面多级结构有助于提升超级电容器电极材料电化学储能性能,以正硅酸四乙酯(TEOS)为硅源,以PVP为助纺剂,运用静电纺丝结合碳热还原技术制备出中空SiC纤维,并采用渗硅技术在SiC纤维表面构筑出球形纳米颗粒的多级结构.研究表明,采用静电纺丝结合碳热还原可以得到具有中空结构、连续性好且结晶程度较高的β-SiC纤维,其比电容为22 F/g.采用渗硅工艺可在β-SiC纤维表面生长球形颗粒多级结构,提升其电化学性能,使其具有较大比电容,为54 F/g.     

氨气还原氮化法制备有序介孔TiN粉体及其电化学性能

以四氯化钛为原料,嵌段共聚物P123(PEO_(20)-PPO_(70)-PEO_(20))为模板剂,氰胺为稳定剂,采用非水解溶胶-凝胶法制备有序介孔TiO_2粉体,再经氨气还原氮化处理得到有序介孔TiN粉体.利用广角/小角X射线衍射、电子显微镜和N_2气吸-脱附等对TiN粉体的结构进行了表征,并通过循环伏安和充放电测试表征了电化学性能.结果显示,该粉体为高纯立方TiN相,呈球形颗粒状,具有有序介孔结构,比表面积高达97 m~2/g.在不同扫描速率下循环伏安曲线均呈类矩形,根据电流密度为50 m A/g时的恒流充放电(GCD)曲线计算比电容为233 F/g,且经2000次充放电循环后比容量仍保持90%以上,在功率密度为0.1 k W/kg时能量密度高达65 W·h·kg~(-1).     

一种应用于HIRFL-CSR上的非拦截式剩余气体电离束流剖面探测器(英文)

兰州重离子加速器冷却储存环主环（CSRm）上成功应用了一种剩余气体电离剖面探测器（IPM）,这种新型非拦截式剖面探测器的应用服役对CSRm的束流冷却研究及常规调束的实时剖面监测具有重要意义。IPM探测器通过收集束流与剩余气体之间的电离产物（气体离子或电子）,利用偏转静电场将电离产物加速至多重微通道板（MCP）,并在其上进行电子放大,放大的信号电子随后在荧光屏（P46等）上进行电子-光子转换,最终含有束流剖面信息的投影光子被真空靶室外的CCD相机获取。在正式应用于CSRm之前,IPM探测器还在分离扇回旋加速器直线（SSC Linac）上进行了束流实验,并与传统单丝扫描剖面探测器进行了对比。IPM探测器与单丝刮束器的剖面测量结果相近,并且具有较好的信噪比和约60 μm的较高空间分辨率。这种IPM探测器可以利用电阻串联进行均匀分压,较便捷地应用于真空度较低的直线加速器,还可以改造为分离电极单独供压的结构,应用在超高真空需要烘烤的环形加速器。最后还介绍了一种全新紧凑型结构的IPM探测器设计,该设计利用一套IPM探测器实现束流横向水平与垂直两个方向的剖面测量功能,这种紧凑型IPM结构尤其在空间紧缺型的强流直线加速器上具有重大的应用价值。A new non-intercepting beam profile monitor, residual gas Ionization Profile Monitor (IPM), has been developed and tested at the main Cooling Storage Ring of Heavy Ion Research Facility in Lanzhou (HIRFL-CSRm). It has been successfully used for studies of electron cooling mechanisms, as well as profile monitoring under normal-mode operation in HIRFL-CSRm. The IPM measures the distribution of ions resulting from the residual gas ionization during the beam passage. The gas ions are collected and multiplied by tandem-type MCPs and a phosphor screen, and eventually captured by a commercial CCD camera outside the vacuum chamber. Before formally applied in HIRFL-CSRm, the IPM was tested and compared with a conventional wire scanner profile monitor at Sector Separated Cyclotron Linac (SSC Linac). Both results show good agreement. Besides, the IPM has higher signal to noise ratio than the wire scanner. It also has a very high spatial resolution of around 60 μm. This monitor can be used for low vacuum like Linac with resistance for bias voltage, or for ultra-high vacuum with discrete electrodes for bias voltage where the bakeout process is essential. Furthermore, a novel and compact design of one IPM with capability of detecting both horizontal and vertical profile is proposed. This compact IPM is quite suitable for non-invasive profile diagnostics at space shortage and high-current Linac.     

PVP对碳热还原氮化法制备TiN薄膜的影响

采用四氯化钛的无水乙醇溶液为钛源,以聚乙烯吡咯烷酮(PVP)为成膜助剂及还原助剂,利用碳热还原氮化技术,在N2气氛下经1300℃进行还原氮化5h制备出TiN薄膜.采用XRD和SEM研究了PVP分子量及其用量对TiN薄膜微观结构的影响.结果发现,随着PVP分子量增大,薄膜中TiN晶体沿(111)面择优生长趋势减小,PVP分子量为1300000时薄膜中TiN晶粒尺寸较大,晶界减少.当PVP用量由钛/碳摩尔比为1∶10增加到1∶12时,TiN薄膜裂纹减少,而增至1∶14时,TiN薄膜中气孔增多.TiN薄膜的生长过程为:TiN颗粒状晶核逐渐生长成棒状,然后继续生长形成片状三角形或六边形,最后呈现出三角锥或六棱台形.     

同轴静电纺丝制备仿生多孔氧化铝纤维研究

以无水氯化铝为原料,聚乙烯吡咯烷酮(PVP)为助纺剂,无水乙醇为溶剂,采用同轴静电纺丝法制备出氧化铝凝胶/PVP前驱体纤维,经1200℃煅烧后得到仿生多孔氧化铝纤维.系统研究了内外液流速以及PVP用量对多孔氧化铝纤维物相和孔结构的影响.结果表明,适当加大内液流速纤维逐渐出现仿生多孔结构,内液流速过大则会导致纤维多孔结构破裂消失.随着外液流速增加,纤维中的孔结构数量和孔径逐渐减小.增加PVP用量纤维直径增大,孔结构数量及孔径也会减小.当内液流速为0.1 mL/h,外液流速为1.0 mL/h,PVP用量为0.5g时,纤维为高纯α-Al203相,纤维表面光滑、连续,具有明显的仿生多孔结构.     

Comparative Studies on Two 1,8-Naphthalimide Derivatives with Experimental and Theoretical Methods

Two 1,8-naphthalimide derivatives of 7H-benzimidazo[2,1,-a]benz[de] isoquino- lin-7-one（1） and 4-bromo-7H-benzimidazo[2,1,-a]benz[de]isoquinolin-7-one（2） have been synthesized and characterized by elemental analysis, IR, 1H NMR, UV-Vis and fluorescence spectra. For the two compounds, density functional theory（DFT） calculations of the structures and natural population atomic charge analysis have been performed at the B3LYP/6-311G＊＊ level of theory. Based on Onsager reaction filed model and by using TD-DFT method at the B3LYP/6-311G＊＊ level, electron spectra of 1 and 2 with solvent effect in CHCl3 solvent have been predicted, which are in agreement with the experimental ones. Comparative studies on 1 and 2 indicate that introducing an electron-withdrawing group of Br into the 4-position of naphthalene ring in 2 does not significantly make the molecular geometry of 2 different from that of 1, but evidently changes the atomic charge redistribution, moves the positive-negative charges center and then changes the dipole moment in 2. Additionally, for compound 2, the existence of Br atom has also influenced the peak intensity and peak locations in both electron and fluorescence spectra.     

纳米级SnO2或Yb2O3对熔融石英陶瓷析晶性能的影响

通过XRD分析和热膨胀率实验,从析晶角度探讨了添加纳米级SnO₂或Yb₂O₃对熔融石英陶瓷析晶性能的影响。结果表明:熔融石英陶瓷高温析晶的主要晶化产物为方石英,方石英析出量随烧结温度的提高而逐渐增多;纳米级SnO₂或Yb₂O₃的引入可通过抑制熔融石英中方石英的析出,有效地降低熔融石英材料在升温过程中的热膨胀率,并且随着烧结温度升高需要不断调整添加剂用量,纳米级SnO₂和Yb₂O₃的最佳用量(质量分数)分别为1%和2%。