Cd_(1-x)Zn_xS(x=0.88)多晶薄膜的制备及性能研究

采用真空共蒸发法制备了Cd1-xZnxS多晶薄膜,研究了Cd1-xZnxS(x=0.88)多晶薄膜的结构与光电特性。XRD的结果表明,0x≤0.9,Cd1-xZnxS薄膜为六方结构,高度择优取向;荧光光谱分析与Ve-gard定理的结果以及石英振荡法监测的Cd1-xZnxS多晶薄膜的组分吻合;制备的Cd1-xZnxS多晶薄膜的光学透射谱的吸收边随Zn含量的增加发生蓝移,其光学能隙调制在CdS与ZnS能隙之间;最后测量了Cd1-xZnxS薄膜室温电阻率及暗电导率随温度的变化情况,计算了Cd1-xZnxS薄膜的电导激活能。     

磁控溅射制备Ni亚微米管阵列及微结构研究

以阳极氧化铝(AAO)为模板,利用磁控溅射法制备了Ni亚微米管阵列。通过X射线衍射仪(XRD)、原子力显微镜(AFM)、扫描电子显微镜(SEM)等手段对沉积态以及经过400℃退火保温不同时间制备的Ni亚微米管阵列的物相结构及微观形貌进行了表征。结果表明：磁控溅射法制备的Ni亚微米管阵列具有多晶的面心立方结构。随着退火时间的增加,Ni亚微米管逐渐增多,Ni衍射峰强度逐渐降低。经400℃退火3h后,获得结构完整、高度有序的Ni亚微米管阵列,Ni亚微米管的大小均匀,外径约为400nm,内径约为200nm,长度约为500nm。     

钛基钙钛矿陶瓷粉体的溶胶-水热法合成机理研究

采用溶胶-水热法,在较低的温度下已成功地合成了多种结晶良好的纳米或亚微米钛基钙钛矿型陶瓷粉体.在本文中通过对溶胶-水热法合成PbTiO3的各阶段产物的X射线衍射谱(XRD)和红外光谱 (IR) 的分析研究,获得了其初步的合成机理:溶胶过程缩短了其反应扩散距离,促进了水热反应的进行.由于该方法合成温度低,可用于多种陶瓷亚微米粉、纳米粉的制备,因此对其反应机制的深入研究有利于纳米粉末合成技术的发展.     

Ni(OH)2亚微米片的水热合成与表征

以Ni(NO3)2·6H2O和NaOH为原料,在水热条件下制备了氢氧化镍亚微米片.运用X射线衍射仪(XRD)、透射电子显微镜(TEM)、傅里叶红外光谱(FT-IR)对样品进行了表征,以氢氧化镍亚微米片作为正极材料做成电池,考察了水热反应pH值对其电化学性能的影响.     

千层饼状Cd(OH)2微米结构的合成与表征

以羰基修饰的聚丙烯酰胺(缩写为PAM-COOH)作为形貌控制剂, 采用水相法合成了千层饼状Cd(OH)₂微米结构. 产物结构与形貌用X射线衍射仪(XRD), 扫描电子显微镜(SEM)、透射电子显微镜(TEM)和选区电子衍射仪(SAED)进行了表征. 研究了不同实验条件(PAM-COOH的浓度、反应物浓度、反应温度和反应时间等)对产物形貌与尺寸的影响. 讨论了PAM-COOH作用下Cd(OH)₂千层饼可能的形成机理. 结果表明, Cd(OH)₂千层饼尺寸约1μm, 每个千层饼由尺寸约为35nm的Cd(OH)₂单晶薄片组成. 反应物浓度、反应温度对Cd(OH)₂尺寸与形貌都有一定的影响, 但起关键作用的是PAM-COOH. 在350℃煅烧Cd(OH)₂ 3h, 得到立方结构千层饼状CdO微米材料.     

Z-机制光催化剂Cd1-xZnxS@WO3-x和Cd1-xZnxS@WO3-x/CoOx/NiOx及其高效可见光解水产氢活性研究（英文）

人工Z-机制光催化剂因其同时具有光吸收范围宽、电荷分离效率高以及载流子氧化还原能力强等优势受到了研究者们的广泛关注.然而,设计和制备能够利用太阳能进行高效光解水产氢的低成本、高稳定性非贵金属Z-机制光催化剂仍具有挑战性.本文报道了一种新颖的全固态Z-机制光催化剂Cd1-xZnxS@WO3-x,该催化剂纳米结构是由氧缺陷WO3-x非晶层包覆Cd1-xZnxS纳米棒组成.研究结果表明,由于适量的Zn掺杂使得Cd1-xZnxS具有更强的产生还原性电子能力,同时, WO3-x超薄非晶层中引入的氧空位(W^5+/OVs)有效地促进了电荷的分离,使得该Z-机制Cd1-xZnxS@WO3-x光催化材料具有优异的光催化产氢反应(HER)活性,且显著高于贵金属Pt负载的Cd1-xZnxS纳米棒(Pt/Cd1-xZnxS及绝大多数WO3和CdS基光催化剂.优化后的Cd1-xZnxS@WO3-x复合光催化剂的HER速率可达21.68 mmol h^-1g^-1.进一步通过原位光沉积负载CoOx和NiO--x双共催化剂, Cd1-xZnxS@WO3-x/Co Ox/Ni Ox复合材料的活性高达28.25 mmol h^-1g^-1,约为Pt/Cd1-xZnxS的12倍.计算结果表明, Cd1-xZnxS@WO3-x在420 nm激发光下的HER表观量子产率(AQY)为34.6%,而负载CoOx和Ni Ox双共催化剂后的Cd1-xZnxS@WO3-x/Co Ox/Ni Ox的AQY提高到了60.8%.此外, Cd1-xZnxS@WO3-x和Cd1-xZnxS@WO3-x/CoOx/NiOx均表现出了良好的长时间HER稳定性.该工作将为理性设计和制备高效光解水产氢催化剂提供新视角.     

水溶性量子点制备条件的优化及表面修饰

以L-半胱氨酸为稳定剂在水溶液中合成CdSe纳米粒子,研究了水浴时间、水浴温度、不同L-半胱氨酸/Cd/Se比例、pH值等因素对其荧光光谱的影响,确定了最佳的合成方案.用CdS对其表面进行修饰,采用透射电镜、X射线衍射、光谱法等表征了Cdse/CdS核壳结构颗粒的形成,结果表明该纳米粒子发光强度明显高于单一的CdSe量子点,光谱峰位置有所红移;合成条件会显著影响CASe/CAS核壳结构量子点的荧光性能.     

应力作用下亚稳Co微粒的结构转变研究

报道了亚微米以及微米尺寸的Co微粒在高温冷却以及应力作用下亚稳结构的稳定性及其结构转变特性.采用扫描电镜,X射线衍射以及振动样品磁强计等对微粒的结构和结构转变特征进行了表征.在相当宽的尺寸范围内,Co由高温冷却至室温和低温过程中保持其亚稳结构(FCC).室温呈亚稳结构的Co微粒极易通过应力诱发转变为HCP结构.根据表面附加压应力对微粒马氏体相变的影响,探讨了微粒尺寸对Co微粒亚稳结构稳定性的影响.     

千层饼状Cd(OH)2微米结构的合成与表征

以羰基修饰的聚丙烯酰胺(缩写为PAM-COOH)作为形貌控制剂, 采用水相法合成了千层饼状Cd(OH)₂微米结构. 产物结构与形貌用X射线衍射仪(XRD), 扫描电子显微镜(SEM)、透射电子显微镜(TEM)和选区电子衍射仪(SAED)进行了表征. 研究了不同实验条件(PAM-COOH的浓度、反应物浓度、反应温度和反应时间等)对产物形貌与尺寸的影响. 讨论了PAM-COOH作用下Cd(OH)₂千层饼可能的形成机理. 结果表明, Cd(OH)₂千层饼尺寸约1μm, 每个千层饼由尺寸约为35nm的Cd(OH)₂单晶薄片组成. 反应物浓度、反应温度对Cd(OH)₂尺寸与形貌都有一定的影响, 但起关键作用的是PAM-COOH. 在350℃煅烧Cd(OH)₂ 3h, 得到立方结构千层饼状CdO微米材料.     

高铬铁基纤维的热稳定性和磁性

高铬铁基纤维由Cu-11Fe-4Cr原位复合丝材硝酸法萃取得到.研究了微米级、亚微米级高铬铁基纤维样品的结构和磁性变化规律.采用X射线衍射和扫描电镜观察分析了样品的结构和形貌,采用振动样品磁强计测试了样品的磁性,利用热重-差热分析比较了不同变形量的高铬铁基纤维在空气中的热稳定性.结果表明:在空气中低于600℃加热1h后,高铬铁基纤维保持BCC结构不变,样品的饱和磁化强度均大于100 A·m2·kg-1;经800℃加热1h后,由铁磁性的α-(Fe,Cr)固溶体转变为顺磁性的(Fe,Cr)2O3,样品的饱和磁化强度显著下降.微米级、亚微米级高铬铁基纤维的热稳定性显著高于微米级多晶铁纤维.随着变形量增大,较细的高铬铁基纤维的热稳定性较差.     

Synthesis of doped ZnS one-dimensional nanostructures via chemical vapor deposition

ZnS one-dimensional (1D) nanostructures doped with Mn or Cd have been rapidly synthesized in large scale via a chemical vapor deposition process. Using Zn and S as precursors and MnCl₂ or Cd as doping source, the doped ZnS 1D nanostructures were obtained. X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) were employed to characterize the as-synthesized ZnS nanostructures. The catalytically grown ZnS 1D nanostructures, including nanowires and nanoribbons, are tens of micrometers in length. All the products are wurtzite ZnS in structure and preferentially grow along the [001] direction. The room temperature photoluminescence properties of these doped ZnS nanostructures are presented.     

Fabrication of large-scale ultra-fine Cd-doped ZnO nanowires

We demonstrate bulk synthesis of highly crystal Cd-doped ZnO nanowires by using (Cd + Zn) powders at 600 °C. These mass ultra-fine ZnO nanowires with about 0%, 1%, 4% and 8% Cd so obtained have been characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), selected area electron diffraction (SAED) and high-resolution TEM (HRTEM). They have the uniform diameter of about 20 nm and several hundred microns in length. The growth of the as-synthesized nanowires is suggested for self-catalyzed vapor–liquid–solid.     

金属Cd~(2+)掺杂TiO_2纳米颗粒的制备及能级结构的影响机理

采用溶胶-凝胶法制备了Cd2+掺杂改性TiO2纳米颗粒,利用XRD、TEM、XPS和UV-Vis光谱对掺杂前后颗粒的结构和性能进行了表征。结果表明,溶胶-凝胶法制备的Cd2+掺杂TiO2纳米颗粒主要为锐钛矿相,粒径尺寸在20nm左右,掺杂前后TiO2的尺寸和形貌没有明显变化;结构表征和光谱测试结果发现,Cd元素在TiO2纳米颗粒中部分取代TiO2晶格中的Ti元素,以Cd2+的形式存在,形成Cd—O键,使TiO2纳米颗粒的吸收带边红移,降低了TiO2的禁带宽度。并且采用基于密度泛函理论的第一性原理对Cd掺杂TiO2进行了能级结构的模拟计算,发现理论结果与实验结果有较好一致性。     

Electrochemical deposition and characterization of elongated CdO nanostructures

CdO nanostructures were synthesized by electrodeposition on the indium doped tin oxide conducting glass substrate at low temperatures (70, 80 and 90 °C) from aqueous solution. Scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-vis spectroscopy and X-ray photoelectron spectroscopy (XPS) were employed to characterize the CdO nanostructures. The results demonstrated that the CdO nanostructures synthesized by electrodeposition grew preferably along the [1 1 1] and have face-centered cubic CdO structures and possessed good crystallinity. XPS measurements showed that the nanostructures had Cd and O elements present in the oxide state and no traces of metallic Cd were observed. The nanostructures were highly transparent in the visible region of spectrum and their energy gap was about 2.45 eV.     

水热法合成N-乙酰-L-半胱氨酸稳定的Cd_xZn_（1-x）Se合金量子点

采用了N-乙酰-L-半胱氨酸为稳定剂,通过水热法制备了荧光发射峰可调、粒径均匀且结晶性能良好的ZnxCd1-xSe合金量子点,并采用紫外-可见光吸收光谱（UV-Vis）、荧光光谱（PL）、X射线衍射（XRD）、高分辨透射电镜（HRTEM）等对其结构和性能进行了表征。重点研究了Cd2＋/Zn2＋比值、初始溶液pH值、水热反应温度和时间等实验条件对ZnxCd1-xSe量子点荧光性能的影响。研究表明所制备的量子点荧光量子产率高（35%）,荧光发射谱半峰宽窄（FWHM〈50nm）,有望作为生物荧光标记物。     

One-step and rapid synthesis of composition-tunable and water-soluble ZnCdS quantum dots

ZnCdS quantum dots have been successfully prepared at room temperature in aqueous solution with sodium hexametaphosphate as stabilizer and thioacetamide as the source of S. The photoluminescence (PL) spectra and UV-Vis absorption spectra of the ZnCdS quantum dots were determined on the basis of the initial Cd/Zn mole ratio (Cd/Zn = 8/0, 7/1, 6/2, 5/3, 4/4, 3/5, 2/6, 1/7 and 0/8) and the concentration of thioacetamide. The emission peaks first showed a red shift and then a blue shift with the increasing initial Zn concentration, which provided the evidence of formation of CdS/ZnCdS core/shell and ZnCdS alloyed quantum dots. The ZnCdS quantum dots were compared with CdS (ZnS) quantum dots doped with Zn2+ (Cd2+). The samples have also been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectra (XPS).     

Fabrication of metallic Cd multifarious prismatic microcrystals (CMPMCs) under NH3 gas ambient

We report here highly dense and pure metallic cadmium (Cd) multifarious prismatic microcrystals (CMPMCs) fabricated by thermal decomposition of cadmium oxide (CdO) powder at 700 °C for 60 min under NH₃ gas ambient inside horizontal tube furnace. CMPMCs were observed to be 1-1.5 μm in size with interesting morphologies of various cross sections such as triangular, trapezoidal, pentagonal and hexagonal etc. having solid, hollow/semi-hollow appearances. The as-synthesized CMPMCS were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and selected area electron diffraction (SAED). Room temperature photoluminescence (PL) spectrum for Cd metal microcrystals exhibited a prominent emission band at 365 along with a shoulder peak at 404 nm. The UV main emission band is ascribed to radiative recombination of the electrons in the s, p conduction band near the Fermi surface and holes in the d bands generated under xenon light excitation whereas shoulder peak may be owing to surface oxidation effects or induced defects. This study shows the potential of CMPMCs for applications in optical devices. Based on vapour-solid (VS) process, growth mechanism for the formation of CMPMCs is also proposed and discussed briefly.     

Polymer-matrix nanocomposite gas-sensing materials

A new approach has been proposed for producing nanocomposite gas-sensing materials: in situ preparation of a polymer matrix and metal sulfide or oxide nanoparticles through the frontal polymerization of Co(II), Cd(II), Zn(II) and Pb(II) acrylamide complexes. The composition and structure of the nanocomposites thus obtained have been determined using X-ray diffraction, scanning and transmission electron microscopy, and Raman spectroscopy. The nanocomposites have been tested as room-temperature liquefied petroleum gas sensors.     

微晶纤维素/CdS纳米复合材料的原位复合反应

以微晶纤维素(MCC)为模板,采用原位复合法制备MCC/CdS纳米复合材料。研究了超声波预处理以及镉离子、硫离子物质的量比对复合效果的影响,用扫描电镜(SEM),原子力显微镜(AFM),X射线衍射,荧光光谱(PL)以及激光共聚焦显微镜(CLSM)对复合材料的结构及性能进行表征。研究表明,超声波预处理后的纤维素对镉离子吸附能力更强,粒径为30 nm~100nm的CdS粒子均匀分布于纤维素表面,所得CdS为立方型晶体,复合材料体现出一定强度的光致发光性,较佳Cd2+∶S2-(物质的量比)为3∶1。