球磨对ZnO的结构、形貌和电化学性能的影响

通过机械球磨对ZnO粉末进行处理. 采用XRD、SEM对不同球磨时间的ZnO粉末的相结构和形貌进行表征, 用恒电流充放电实验研究其在锌镍电池体系中的放电特性和循环稳定性, 并结合循环伏安法探讨其充放电机理. 实验结果表明, 球磨过程中位错的形成和运动导致晶粒尺寸的减小和晶格应变值的增大, 晶粒尺寸由135.6 nm减小至17.9 nm, 晶格应变值相应地从0.06%增加到0.57%. 球磨处理提高了ZnO粉末的电化学反应活性, 因而其放电容量逐渐增加. 当球磨时间达到100 h时, ZnO的放电容量达到300.6 mAh/g, 比未球磨的高50 mAh/g.     

AZ31镁合金粉末氢气氛下机械球磨的组织演变

在氢气氛下机械球磨AZ31镁合金粉末,利用机械力作用使镁合金粉末与氢气发生反应生成纳米晶MgH2,用X射线衍射(XRD)、扫描电镜(SEM)和透射电镜(TEM)等方法观察和分析了镁合金粉末与氢气在球磨过程中的微观组织演变.结果表明:球磨初始阶段粉末颗粒被碾压成扁平状,随着球磨的进行粉末颗粒逐渐细化,球磨至80h,形成粒度1～3μm、晶粒尺寸10nm左右的纳米晶MgH2粉末材料.     

Fe-Ce-Ni纳米晶粉体的机械合金化研究

研究按物质的量配比分别为n(Fe-Ce)∶n(Ni)=0.7∶0.3和n(Fe-Ni)∶n(Ce)=0.8∶0.2的混合粉体在机械合金化过程中的结构演变和软磁性,采用X射线衍射法表征机械合金化粉体的结构演变过程,用振动样品磁强计对样品的静磁性能进行测试分析。结果表明:球磨150 h后,按物质的量配比为n(Fe-Ce)∶n(Ni)=0.7∶0.3和n(Fe-Ni)∶n(Ce)=0.8∶0.2的混合粉体都分别成为纳米晶粉体,球磨时间和Ni成分的含量都对其软磁性能有影响。     

化学共沉淀粉体制备ZnO压敏电阻

本文采用化学共沉淀法制备了颗粒细、活性好的ZnO压敏电阻粉体,表征了粉体的性能．利用共沉淀粉体制备了α＝50、压敏电压高、通流能力大的压敏电阻．与传统氧化物机械混合粉体制得的压敏电阻比较,共沉淀粉体获得的压敏电阻微观结构均匀．     

Nanocrystalline Oxide Ceramics Prepared by High-Energy Ball Milling

Studies of grain size effects in nanocrystalline materials require a preparation technique which allows adjustment of the grain size. We prepared various nanocrystalline ceramics by high-energy ball milling. The investigated systems are the oxide ceramics Li₂O, LiNbO₃, LiBO₂, B₂O₃, TiO₂ as monophase materials and the composite material Li₂O : B₂O₃. The average grain size was adjusted by variation of the milling time. It was determined via line broadening of X-ray diffraction patterns (XRD) and directly with transmission electron microscopy (TEM). Thermal stability and thermally induced grain growth of the samples can be observed with differential thermal analysis and X-ray analysis. Further information concerning the structure of these heterogeneously disordered materials was extracted from nuclear magnetic resonance (NMR) and infrared spectroscopy. Li diffusion in the lithium-containing compounds is studied with ac conductivity measurements, as well as [⁷Li] NMR relaxation spectroscopy. The TiO₂ is interesting for research on catalytic activity. Ball milling not only causes particle size reduction, but may also lead to phase transitions and chemical reactions. This was verified with XRD.     

Induced Room-Temperature Ferromagnetism in Un-doped Nanocrystalline Metal Oxide Powders Obtained by Mechanical Milling: A Review

In the past few years, considerable research work has been carried out in order to understand the origin of ferromagnetism in un-doped oxide semiconductors. The debate is still open, but most of the experimental and theoretical studies suggested that defects may induce room-temperature ferromagnetic order. This brief review will focus on some very recent works based on the use of mechanical milling as a processing approach in order to induce defects and transform the initial diamagnetic or paramagnetic powders to ferromagnetic order.     

热蒸发锌粉法制备半导体氧化锌纳米线的研究

采用热蒸发锌(Zn)粉的方法,制备出高产量的由半导体氧化锌纳米线组成的蒲公英花状和四角锥状纳米结构.利用SEM、TEM和X射线衍射对产物的形貌及结构进行了分析.结果表明,所生成的是具有六方结构的单晶ZnO纳米线.纳米线长约5-10μm,根部直径较粗,约110-120nm;梢部较细,约25-30nm,其生长机制为气-固(VS)机制.     

单分散纳米氧化铟锡粉末的水热合成

以金属铟和锡为原料,于碱性环境240℃水热合成12h并经500℃煅烧2h得到了 粒径为70±10nm,比表面积为11 m²／g的高纯氧化铟锡(ITO)粉末.由SEM、激光粒度测试 仪和BET三种方法分析得到的粉末平均粒径相吻合,证明制备的粉末是单分散状态的.研究 还发现,提高铟锡初始浓度和氢氧化钠过量浓度均有利于小粒径单分散ITO粉末的制备,但 过高的氢氧化钠过量浓度会使粉末出现团聚.     

微波法制备纳米氧化锌及其光催化性能研究

以硫酸锌和尿素为原料,采用微波加热法制备纳米氧化锌,比较了不同工艺条件下制备的纳米氧化锌的性能,结果表明,不同反应时间制备的纳米氧化锌均为六方晶系的纤锌矿结构,颗粒大小平均为52．14nm,反应时间、反应物浓度及焙烧温度对纳米氧化锌的光催化性能均有一定的影响。反应时间1．5h、硫酸锌的浓度0．25mol／L、焙烧温度450℃时,纳米氧化锌的光催化效果较好。     

杂质元素对锌蒸气氧化产物形貌的影响分析

以Zn 99.995级纯金属锌为原料,分别掺入Pb、Cd、Cu、Sn、Al和Sb等杂质金属元素,熔化后加入到蒸发炉内,产生的锌蒸气被氧化成为氧化锌.结果表明,当杂质元素掺入量为0.5%时,掺Pb、Cd、Sn、Al和Sb的产物中均含有四针状氧化锌,而掺Cu的产物中为不规则的片状和单针状.随着杂质元素掺入量的增加,Pb、Sn和Al对四针状氧化锌形成的影响相对较小.掺入1%Pb、Cd的产物为六方纤锌矿结构的氧化锌.杂质元素改变了氧化锌的形核和晶须的长大过程,导致氧化锌产物的形貌发生了变化.     

硅烷偶联剂对金属氢氧化物粉体的机械球磨改性

为改善金属氢氧化物粉体的分散性及对其表面亲和力,采用机械球磨法利用硅烷偶联剂KH-550对氢氧化镁、氢氧化铝阻燃剂粉体进行表面改性。通过X射线衍射、红外吸收光谱及扫描电镜等测试手段,对比分析不同酸、碱条件下硅烷偶联剂KH-550对氢氧化物阻燃剂的改性效果,对反应机理进行分析和探讨。结果表明:球磨改性更有利于粉体的分散和细化;当介质为酸性条件时,硅烷偶联剂KH-550对氢氧化物粉体的改性效果最佳。     

以尿素为沉淀剂制备纳米氧化锌粉体

本文以尿素,硝酸锌为原料,采用均匀沉淀法制备了纳米级ＺｎＯ．以ＴＧ－ＤＴＡ热分析,红外光谱及ＸＲＤ,ＴＥＭ,激光衍射粒度分析仪等测试手段,对纳米级ＺｎＯ的粉体结构和形貌进行了研究。结果表明,在４５０℃下热处理得到的纳米ＺｎＯ粉体结晶性能良好,改变反应条件,制备了平均粒径在１５－８０ｎｍ,粒度分布窄,分散性好的纳米ＺｎＯ粉体。     

Influence of Milling Conditions on the Mechanical Alloying of Fe-B Powders

1.IntroductionTheFe-Bamorphousalloyshavebeensynthesizedinawideconcentrationrangebymeltquenching[1ro2]orvacuumevaporation[3~5].Recently,someworkshowedthatamorphousalloysoftheFe-Bsys-temhadbeensuccessfullypreparedbymechani-calalloying[6~1o].Inthispaper3amorphousandnanocrystallineFe-Balloysmadebymechanicalal-loyingofelementalFeandamorphousBpowdersinawidecompositionrangearestudiedbyX-raydiffrac-tion,M6ssbauerspectroscopyandthermalanalysismeasurements.Especially,theeffectsofmillingcondi-tions,s…     

反应沉积法制备c轴取向ZnO薄膜及表征

以二水合醋酸Zn为原料 ,采用反应沉积方法在非晶玻璃衬底上制备出了高度c轴取向、结晶良好的ZnO薄膜。研究了不同衬底温度和Zn源温度对ZnO薄膜性质的影响 ,探讨了不同衬底温度和Zn源温度下生长ZnO薄膜的最佳参数。本文还讨论了该方法制备ZnO薄膜的沉积机制及优化条件下样品的透光特性。     

高能球磨纳米CeO2/Zn复合粉末的热压烧结

采用真空热压工艺制备了纳米CeO2/Zn复合材料块体,并用正交实验法研究了热压工艺参数对复合材料块体相对密度的影响.结果表明:随着粉末球磨时间的增加,复合材料块体内纳米颗粒分散越均匀,基体晶粒不断细化;块体的相对密度随着热压温度、压力的提高和保温时间的延长而增加,其中热压温度的影响最大,压力影响次之,保温时间影响最小;制得的纳米复合材料块体可加入到热浸镀锌液中.     

Microstructure and Mechanical Property of 2024 Aluminium Alloy Prepared by Rapid Solidification and Mechanical Milling

Rapidly solidified 2024 aluminium alloy powders were mechanically milled, then consolidated to bulk form. The microstructural changes of the powders in mechanical milling (MM) and consolidation process were characterized by X-ray diffraction analyses and transmission electron microscopy observations. The results showed that mechanical milling reduced the grain size to nanometer, dissolved the Al2Cu intermetallic compound into the aluminium matrix and produced an aluminium supersaturated solid solution. During consolidation process. the grain size increased to submicrometer, and the Al2Cu and Al2(Cu, Mg, Si, Fe, Mn) compounds precipitated owing to heating. Increasing consolidation temperature and time results in obvious grain growth and coarsening of second phase particles. The tensile yield strength of the consolidated alloy with submicrometer size grains increases with decreasing grain size, and it follows the famous HallPetch relation     

铝钼共掺杂氧化锌粉末的制备及光电性能研究

采用水热法制备了不同含量的铝(Al)单元掺杂及铝(Al)、钼(Mo)共掺杂氧化锌(AZO、AZMO)纳米粉体,利用X射线衍射(XRD)、扫描电镜(SEM)、高分辨透射电镜(HRTEM)、荧光分光光度计(PL)、紫外分光光度计(UV-vis)、TG-DTA差热分析、激光粒度分析仪、四探针电阻测试仪等测试手段,探究了Al单元掺杂和Al、Mo共掺对AZO、AZMO粉体结构、形貌及光电性能的影响.结果表明:所制备的AZO和AZMO纳米粉体为结晶度良好的六方纤锌矿结构.Al、Mo掺杂浓度影响纳米氧化锌粉体形貌、晶体结构及光电性能.随着Al、Mo掺杂浓度的增加,粉体的结晶质量降低,晶粒尺寸先减小后增大,光电性能先变好后变差.适度的Al、Mo共掺杂可使氧化锌禁带宽度和电阻率达到最优匹配,改善氧化锌的近紫外发光和蓝色发光特性.在掺杂浓度为m(Al):m(Mo)=1:3时,纳米粉体的综合光电性能最佳,禁带宽度为3.392 eV,电阻率为20.3Ω·m,紫外发光峰强度最大,且出现了蓝移.     

共沉淀包膜法制备氧化锌压敏陶瓷粉料的研究(Ⅱ)

本文在前期研究工作的基础上 ,重点研究了五元掺杂组分共沉淀包膜ZnO微粒的过程中各种因素对粉料mol%配比、粒度分布、颗粒形状及电性能的影响 ,优化工艺参数 ;对三种制粉方法的压敏陶瓷电性能进行了比较 ,在此基础上建立氧化锌压敏陶瓷制粉新方法。     

Novel Carbon Dioxide Microsensor Based on Tin Oxide Nanomaterial Doped With Copper Oxide

Carbon dioxide $({rm CO}_{2})$ is one of the major indicators of fire and therefore its measurement is very important for low-false-alarm fire detection and emissions monitoring. However, only a limited number of ${rm CO}_{2}$ sensing materials exist due to the high chemical stability of ${rm CO}_{2}$. In this work, a novel ${rm CO}_{2}$ microsensor based on nanocrystalline tin oxide $({rm SnO}_{2})$ doped with copper oxide (CuO) has been successfully demonstrated. The ${rm CuO}hbox{-}{rm SnO}_{2}$ based ${rm CO}_{2}$ microsensors are fabricated by means of microelectromechanical systems technology and sol-gel nanomaterial-synthesis processes. At a doping level of ${rm CuO}:{rm SnO}_{2} =1:8$ (molar ratio), the resistance of the sensor has a linear response to ${rm CO}_{2}$ concentrations for the range of 1% to 4% ${rm CO}_{2}$ in air at 450$^{circ}{rm C}$. This approach has demonstrated the use of ${rm SnO}_{2}$, typically used for the detection of reducing gases, in the detection of an oxidizing gas.