高温固相法制备CaCO_3:Eu~(3+),Li~+红色荧光粉

以CaCO3、Eu2O3和Li2CO3为主要原料,采用高温固相法,首次制备CaCO3:Eu3+,Li+红色荧光粉。通过对前驱物进行同步差热分析(TG-SDTA),确定其煅烧温度;利用X射线衍射(XRD)、傅立叶变换红外光谱(FT-IR)和拉曼光谱对样品的结构进行表征;采用荧光光度仪对样品的发光性能进行测试。结果表明:前驱物的煅烧温度为655℃时,样品主晶相为方解石型CaCO3,掺杂Eu3+和Li+离子分别作为发光中心和敏化剂进入到CaCO3的晶格中。荧光粉的最大激发峰位于272nm,属于紫外激发,最大发射峰位于608nm附近,对应于Eu3+离子的5d0→7f2跃迁,并且Eu3+离子在CaCO3基质中处于偏离或无反演对称中心的格位上。     

高温固相法制备锆英石工艺研究

为研究高温固相法制备锆英石的最佳工艺条件,以不同粒度的SiO2和ZrO2粉体为原料,在1 500℃条件下通过不同的保温时间进行锆英石的制备。利用激光粒度分析、X射线衍射、扫描电镜等手段对原料的粒度、物相与结构和微观结构进行表征。结果表明:不同粒度的SiO2和ZrO2粉体在1 500℃条件下通过保温1.5、3、4.5、6 h均可制备出锆英石,但d50=2.125μm的原料通过保温4.5、6 h所制备出的样品效果最好。利用高温固相法进行锆英石的工业化生产,原料的d50控制在2μm左右,在1 500℃条件下保温4.5 h的生产工艺比较合适,所制备样品的晶粒度主要集中在0.2~1.5μm之间。     

室温固相法制备纳米氧化铋

以NaOH和Bi(NO_3)_3·5H_2O为原料,并添加不同的分散剂,采用室温固相法制备了纳米Bi_2O_3采用XRD、TEM表征纳米Bi_2O_3的结构和形貌。结果表明,分散剂种类、分散剂的添加量等因素显著影响纳米Bi_2O_3结构和形貌。     

ZnS:Mn荧光粉的溶剂热法制备及其发光性能

采用溶剂热法合成了ZnS∶Mn荧光粉,讨论了锰掺杂量对硫化锌发光性能的影响。通过扫描电镜(SEM)、X射线粉末衍射仪(XRD)、紫外可见分光光度计(UV-Vis)和荧光分光光度计(PL)对合成的ZnS∶Mn荧光粉的结构和光学性能进行了表征。结果表明:ZnS∶Mn荧光粉的平均粒径为13.5nm,在波长340nm~200nm处有强吸收,Mn离子浓度在所研究范围内,锰掺杂量对硫化锌的晶型、结晶度、粒径无影响,但对其能级结构影响显著,且随着Mn离子掺杂量的增加,发光强度先增加后减小,掺杂量为5%时达到最大值。     

室温Zn粉直接制备ZnO纳米颗粒薄膜及其机理研究

首次在室温条件下超声方法直接将金属Zn制备ZnO纳米颗粒薄膜。利用滚压振动磨机械研磨的Zn粉作为原料,采用独特的油相水相混合溶液作为分散液,超声分散打破软团聚使金属Zn纳米颗粒水解得到了分散性较好的纳米粒子,并且可以利用该纳米粒子简单地制备出均匀致密的ZnO纳米粒子薄膜。利用X射线粉末衍射仪(XRD)、透射电子显微镜(TEM)对产物进行了表征。结果表明,采用该方法可制得具有密排六方结构的ZnO纳米颗粒,并且该产物分散较好。原子力显微镜(AFM)、静电力显微镜(EFM)表明利用该纳米粒子制备的薄膜致密均匀,EFM显示纳米粒子表面电学性质有较大差异。探针台I-V测试显示不同原料Zn粉制备出的ZnO纳米颗粒薄膜可以获得不同导通电压从而获得不同的整流效果。该方法在室温条件下由Zn粉制备出ZnO纳米颗粒和薄膜,为制备不同维度ZnO纳米结构提供了新思路,同时也为制备、改善整流器件提供了创新和经济的途径。     

固相法制备超细二氧化硅粉体

以水玻璃和硝酸铵为原料,用固相法制备了二氧化硅超细粉体,并用SEM、XRD对粉体进行了表征.结果表明,粒子呈球形,粒子直径为70～80 nm.固相法操作方便、合成工艺简单,是一种制备高产率单分散超细氧化物的有效方法.     

固相法制备高温稳定的β-TCP

本文以商用材料为原料,用传统的固相法制备了β-TCP粉末.用DTG、TG、DTA测定了混合粉末加热过程中的重量变化和热流.用XRD相分析方法监测加热过程中每个步骤的相变.在分析测试的基础上分析了反应细节.制备的β-TCP粉末具有高温稳定性,测定出它从β相到α相的相变温度为1350℃,比商用β-TCP粉末高200℃.高的相变温度源于原材料中微量Mg的存在.     

ZnO:Zn的光致发光和电致发光性能

在N2 H2还原气氛中以ZnO粉末为原料制备了ZnO:Zn发光膜和粉末.利用X射线衍射、电子扫描显微镜、红外光谱仪、XPS、荧光分光光度计等测试手段表征了样品的结构、形貌、缺陷和发光性能.ZnO:Zn发光膜具有六角纤锌矿晶体结构和良好的c轴取向,结晶性较好,晶粒颗粒均匀.ZnO:Zn发光膜和粉末具有绿色的单谱光致发光和电致发光.发光薄膜的O1s结合能表明,此绿色发光与薄膜内的点缺陷状态密切相关.     

固相硒化镉的化学合成

利用室温固相化学反应,合成了立方相的硒化镉(CdSe)纳米颗粒,并采用XRD、TEM的分析手段对其结构和形貌进行了表征.实验结果表明,利用固相化学反应在室温条件下即可得到CaSe纳米材料,该法过程简单,不需要特殊的仪器和设备,易于操作和控制.     

强磁场作用下材料扩散型固态相变的微观机理

为探讨强磁场对物质原子尺度行为(电子运动、离子扩散)的影响,采用光学显微镜研究强磁场作用下Fe-0.12%C合金的扩散型固态相变;采用数字多用表测量强磁场作用下的纯铝板电阻研究其电子分布.结果表明:随磁感应强度增强,Fe-0.12%C合金室温显微组织中,铁素体晶粒平行于磁场方向伸长并呈链状排列的趋势增强,珠光体团的长轴方向平行于磁场方向伸长的程度也增强;纯铝板的电阻在平行于磁场方向放置时减小,垂直于磁场方向放置时电阻有增加趋势.这是由于组成金属晶体的自由电子和排列成晶格状的金属离子在磁场作用下受到洛伦兹力的作用,随磁感应强度增强,沿磁场方向的电子浓度、金属离子扩散有增强趋势,导致磁场作用下材料扩散型相变的室温组织出现形状各向异性.     

ZnO:Zn粉末的合成及其电致发光特性的研究

通过均匀沉淀的方法制备出了ZnS颗粒,并以此作为源材料,结合不同表面活性剂的性质,通过热灼烧的方法合成了ZnOZn颗粒,采用X射线衍射等测试手段对材料的结构进行了表征,并对其电致发光性能做了测试.研究结果发现,加入表面活性剂处理后的样品其电致发光峰位并没有发生移动,随着电场强度的增大,发光强度明显增强;另一方面,在同一电场强度下,以18胺处理的样品其电致发光强度比纯ZnO有所提高,但提高的幅度不大,而以F-127处理的样品其电致发光强度比前两者有显著的提高.分析原因,可能是由于在灼烧的过程中,表面活性剂使得ZnO中氧空位的数量发生变化,从而影响到ZnO粉末电致发光强度.     

Vapor phase synthesis of ZnO structures

We observed zinc oxide structures formed in an oxygen-containing atmosphere as a result of oxidation of the surface of zinc droplets. The gas-phase oxidation leads to the formation of hollow ZnO whiskers on the metal surface, which grow due to the transport of zinc vapor through their channels. It was found that high partial pressures of zinc and atomic oxygen give rise to fractal structures, which appear in a cascade process involving the sequential formation of zinc oxide vapor, ZnO clusters, and cluster aggregates as a result of the cluster-cluster interaction. A deposit of ZnO synthesized on the cathode surface exhibits a columnar structure.     

Liquid phase synthesis of ZnO microrods highly oriented on the hexagonal ZnO sheets

We have successfully synthesized zinc oxide microrods perpendicularly oriented on hexagonal ZnO sheets by a simple heat treatment approach using LDH (layered double hydroxide) precursor in an aqueous solution. The synthesized ZnO microrods have an average diameter of 500 nm and length of 2–3 μm, and form highly-oriented array. In this work, the effect of heating temperature and time on morphology and orientation of ZnO microrods was studied experimentally and the formation mechanism was discussed in detail. Transformation from hexagonal precursor to ZnO microrods can be attributed to dissolution and re-precipitation of the precursor, which should be caused by its thermal unstability under heating temperature.     

高压低温制备硅材料的性能研究

研究了用高压低温法制备的硅材料的性能。进行了不同的温度条件下制备陶瓷硅材料的实验研究．获得了最佳的制备条件。用XRD分析了材料的物相；阿基米德法测量了制备材料的密度；对材料的电阻率和硬度进行了测量。结果表明：用高压低温方法可以制备出无氧化相存在的陶瓷硅材料，其最佳的烧结温度为600℃；样品具有较好的机械强度和硬度，获得了适于制备多晶硅薄膜的衬底材料。     

Electro-codeposition synthesis and room temperature ferromagnetic anisotropy of high concentration Fe-doped ZnO nanowire arrays

Fe-doped ZnO dilute magnetic semiconductor (DMS) nanowire arrays were fabricated in anodic aluminum oxide (AAO) membranes using electro-codeposition followed by long-time anneal process. The morphology, chemical composition and crystal structure were characterized by field emission scanning electron microscope (FE-SEM), high resolution transmission electron microscope (HRTEM) equipped with an energy dispersive x-ray spectrometer, and X-ray diffraction (XRD) spectroscopy. The results prove that the Fe has been successfully doped in the lattice of ZnO nanowire arrays and the estimated Fe atomic ratio is around 22%. Micro-superconducting quantum interference device (SQUID) shows that the nanowire arrays exhibit room temperature (300 K) ferromagnetic and anisotropic ferromagnetic behavior which may be a consequence of the easy magnetization direction along the wire axes and magnetostatic interaction.     

ZnO 1-D nanostructures: Low temperature synthesis and characterizations

ZnO is one of the most important semiconductors having a wide variety of applications in photonic, field emission and sensing devices. In addition, it exhibits a wide variety of morphologies in the nano regime that can be grown by tuning the growth habit of the ZnO crystal. Among various nanostructures, oriented 1-D nanoforms are particularly important for applications such as UV laser, sensors, UV LED, field emission displays, piezoelectric nanogenerator etc. We have developed a soft chemical approach to fabricate well-aligned arrays of various 1-D nanoforms like nanonails, nanowires and nanorods. The microstructural and photoluminescence properties of all the structures were investigated and tuned by varying the synthesis parameters. Field emission study from the aligned nanorod arrays exhibited high current density and a low turn-on field. These arrays also exhibited very strong UV emission and week defect emission. These structures can be utilized to fabricate efficient UV LEDs.     

Facile synthesis of ZnO nanocrystals via a solid state reaction for high performance plastic dye-sensitized solar cells

We report the facile synthesis of ZnO nanocrystals via a one-step solid state reaction at room temperature and their application as the photoanode in plastic dye-sensitized solar cells (DSCs). ZnO nanoparticles were prepared utilizing zinc acetate dihydrate and sodium hydroxide with a short grinding time and without a sintering process. The as-prepared samples with the polycrystalline hexagonal wurtzite structure were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The obtained ZnO nanoparticles exhibited high crystallinity even without a high temperature sintering treatment during the preparation process. The effects of compression post-treatment on the photovoltaic performance of DSCs were also investigated using intensity modulated photocurrent spectroscopy (IMPS), incident photo-to-current conversion efficiency (IPCE), and electrochemical impedance spectroscopy (EIS). The results indicate that the improvement of power conversion efficiency after compression post-treatment of ZnO photoelectrode can be attributed to its high photoelectron collection efficiency and effective electron transport. Under the optimized conditions, a full plastic D149-sensitized ZnO solar cell measured under illumination of 100 mW·cm⁻² (AM 1.5G) presents an energy conversion efficiency of 3.76% with open-circuit voltage of 0.688 V, short-circuit current density of 8.55 mA·cm⁻², and fill factor of 0.64. These results demonstrate that the one-step solid state reaction is a convenient and effective method for the synthesis of ZnO nanocrystals for use in plastic DSCs.      

电化学法原位合成Zn/Co-ZIF材料及电容性能

采用电化学法原位合成双金属Zn/Co-类沸石类咪唑骨架材料(ZIF).通过改变反应溶剂配比、电压大小、反应时间及金属钴盐添加量来探究材料的最佳合成条件.在N,N-二甲基甲酰胺(DMF)与乙醇(EtOH)的体积比为1:4,外加电压为5 V,外加金属钴盐为0.08 g时,合成不规则层状颗粒结构的Zn/Co-ZIF.以Zn/...