室温铁磁性GaN:Cr薄膜的性质研究

采用高能离子注入的方式,在GaN衬底中掺杂引入Cr离子制备了磁性半导体.借助于X射线衍射仪(XRD)进行了注入前后结构的对比分析,没有发现新的衍射峰,并运用高分辨率X射线衍射仪(HR-XRD)分析了Mn离子注入后衬底(0002)峰的微小变化.根据原子力显微镜的结果,发现注入后的样品表面起伏比较大,发生明显的变化.通过使用超导量子干涉仪SQUID进行变温分析,在所分析的10～300K范围内,磁化强度变化幅度较小,样品在室温条件下仍然保持铁磁性.     

电泳沉积法制备GaN薄膜的结构和组分分析

采用电泳沉积法在Si(111)衬底上制备出了GaN薄膜.用X射线衍射(XRD)、傅立叶红外吸收(FTIR)谱、X射线光电子能谱(XPS)和扫描电镜(SEM)对样品的结构、组分和形貌进行了分析.结果显示所得样品为六方纤锌矿结构的GaN多晶薄膜.     

配合物热分解制备氮化镓纳米线及其生长机理研究

报道了利用VLS生长机制,在NH3气氛中,由配合物GaCl3·NH3在高温下热分解反应成功制备了GaN纳米线,利用X射线衍射(XRD)、高分辨电镜(HRTEM)、X射线能谱(EDS)等分析手段对产物进行了表征,并对氮化镓纳米线的VLS生长机理进行了探讨。     

植物纤维模板法制备ATO纤维的研究

以阔叶木纤维为模板通过浸渍氯化锡与氯化锑的酒精溶液、空气气氛中煅烧,制备出氧化锡掺杂氧化锑(ATO)的导电纤维.采用X射线衍射、扫描电镜、X射线能谱仪对所制得的纤维进行了表征.结果表明:所获得的ATO纤维保留了天然植物纤维的结构;当掺杂量为10％时,ATO纤维具有最低的电阻率.     

磁性金属纳米结构的制备与表征

采用电化学沉积方法成功地制备了高度有序的镍纳米管/线阵列结构,并用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和X射线衍射(XRD)对产物的微观形貌和化学结构进行了表征和分析.测试结果显示,镍纳米结构阵列规整,镍纳米管壁具有多晶体结构;X射线衍射图谱表明,镍纳米管壁具有较高的结晶度.研究了沉积时间对镍纳米结构的影响.     

模板法合成分叉Ni纳米线阵列及其磁性能

首先采用三次阳极氧化法制备了具有Y形孔道的氧化铝(AAO)模板,然后采用直流电化学沉积法,在模板内成功合成了分叉Ni纳米线的有序阵列.通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)对所合成样品的晶体结构和形貌进行了表征测试.结果表明,制备的Ni纳米线分布均匀、排列有序,呈Y形分又结构,其...     

模板法合成Sr2CeO4纳米线阵列

以多孔阳极氧化铝为模板,采用逆向迁移技术,在模板的纳米孔道内反应形成一维纳米结构前驱体,再经后续处理,制得了Sr2CeO4纳米线.通过X射线衍射光谱(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)等检测手段对产物进行了表征,结果表明,所得Sr2CeO4纳米线阵列排列整齐,单体纳米线的直径大约为60nm,与所用模板的孔径相当,长度可达30μm.     

石墨包覆铁纳米粒子的结构及生长机制

用金属钾还原2阶FeCl3石墨层间化合物(FeCl3-GICs)前驱体制备了石墨包覆纳米α-Fe.X射线衍射(XRD)、X射线能量色散谱(EDX)分析表明所制备样品由石墨、α-Fe和少量KCl组成,透射电镜(TEM)观察发现样品中的α-Fe为纳米粒子,嵌入在石墨结构层间,含量丰富.高分辨透射电镜(HRTEM)观察证实α-Fe纳米粒子由多晶组成,呈二维或准二维形态,α-Fe纳米晶的空间取向严格受石墨结构层控制.在实验基础上提出了一种石墨包覆纳米α-Fe的可能生长机制.     

氧化锌纳米线/管阵列的溶胶-凝胶模板法制备与表征

用溶胶-凝胶法在氧化铝模板中制备了直径约为15、30、50、60nm的有序氧化锌纳米线/管阵列.用扫描电镜(SEM)、透射电镜(TEM)和X射线衍射仪(XRD)对氧化锌纳米线/管的形貌、结构以及相组成进行了分析.结果发现,纳米线的形貌依赖于氧化铝模板中孔洞的形貌,纳米线的长度受控于氧化铝模板的厚度,外径与氧化铝模板的孔径相等.通过控制溶胶的浓度以及氧化铝模板在溶胶中的浸泡时间可以制备出纳米管.     

Ni纳米管的电化学模板法制备及表征

本文采用一种简单而有效的电化学方法在硫酸铵体系中利用氧化铝模板(AAO)成功制备出规则有序的Ni的管状纳米阵列.使用这种方法可获得外径约为70nm,内径约为50nm的Ni纳米管.对所得的Ni纳米管进行了扫描电镜(SEM)、透射电镜(TEM)、选区电子衍射图(SAED)和X射线衍射(XRD)分析,结果表明:该方法制备的Ni纳米管高度有序,大小均一,其形貌受控于氧化铝模板的结构,外径与模板的孔径相等.     

ZnO纳米材料制备及其场发射性能的研究

采用水热法制备形貌和尺寸各异的纳米ZnO材料。用X射线衍射分析仪(XRD)和扫描电子显微镜(SEM)测试产物结构和表面形貌,分析影响纳米ZnO材料生长的因素,探讨纳米ZnO的生长机理。研究了各种形貌ZnO阵列的场致发射特性。实验结果表明,在各种ZnO纳米结构中,纳米管的场致发射性能最好,其最大电流密度可达到0.2mA/cm2,开启场强2.5V/μm,为寻求良好场发射性能的ZnO纳米材料提供了一个可行的途径。     

载银MWNTs抗菌羊毛纤维的结构与性能研究

以载银MWNTs抗茵剂为功能材料,采用紫外光辐照的方法制备了载银MWNTs抗茵羊毛纤维.运用场发射扫描电镜、X射线衍射仪对样品的形貌和结构进行了表征,同时测试了样品的力学性能、热性能和抗茵耐洗涤性能.研究结果表明,抗茵羊毛纤维表面包覆了一层致密的抗茵层;与原毛相比,其结晶指数、单纤强力、断裂强度和热稳定性均有提高,但断...     

Precursor dependent tailoring of morphology and bandgap of zinc oxide nanostructures

Zinc oxide (ZnO) nanoparticles have been synthesized by wet chemical processing from four different zinc precursor materials at room temperature. Synthesis of phase pure material with four different morphologies and orientations have been confirmed through different characterization techniques like, X-ray diffraction, field emission SEM, fourier transformed IR etc. The band gap energies of the synthesized materials were within specific semiconductor limits and the same have been determined from UV–Visible and photoluminescence spectra of the synthesized nanostructured ZnO materials. Thus it is possible to control ZnO nanostructures and morphologies through facile room temperature synthesis and tailor their band gaps for different application purposes.     

Fabrication of ZnO Nanoneedle/nanocolumn Composite Films and Annealing Induced Improvement in Their Microstructural and Photoluminescence Characteristics

ZnO nanoneedle/nanocolumn （NN/NC） composite films were grown via reactive electron beam evaporation （REBE） in the NH3/H2 gaseous mixture by using polycrystalline ZnO ceramic targets as source materials. The growth was performed at low substrate temperatures （450～500℃） without employing any metallic catalysts. As-prepared samples were then rapidly annealed in 02 ambient at a higher temperature （600℃）. Electron microscopic observations revealed the typical composite-structured morphologies of NN/NC/substrate of ZnO nanomaterials grown at 500℃. Such unique morphologies should render potential applications, for instance, as an efficient microwave absorption material utilized in the fabrication of concealed aerostat. In addition, X-ray diffraction and photoluminescence measurements showed remarkable improvement in crystal and optical qualities of ZnO NN/NC composite films after annealing.     

The preparation of magnetite Fe3O4 and its morphology control by a novel arc-electrodeposition method

Magnetite Fe₃O₄ ultrafine powder, a magnetic material, was synthesized by a novel arc-electrodeposition method. The products were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The experimental results showed that the morphologies of the Fe₃O₄ produced were greatly influenced by the diameters of the metallic iron filament electrodes and the electrolyte composition.     

EDTA辅助水热法制备不同形貌的氟化镁钠

以氟化钠、六水合氯化镁为主要原料, EDTA (乙二胺四乙酸二钠盐)为辅助剂, 通过水热法制备出不同形貌的氟化镁钠。考察了溶液pH、反应温度、时间和络合剂对产物形貌和物相的影响, 并对其形成机理进行了探讨。采用扫描电镜(SEM)、X射线衍射(XRD)和傅里叶变换红外光谱(FT-IR)等手段对产物形貌和物相进行了表征。结果表明: 在该反应体系中, EDTA既作为原料提供钠离子, 又作为络合剂与镁离子形成络合物; 反应温度、pH和络合剂对产物的形貌和物相有较大影响; 所得产物结晶度高, 有表面光滑的微米立方体晶体和纳米粒子聚集的微米空心球颗粒, 粒径均在1~3 μm之间。     

TEM and molecular simulation studies on the hydroxylapatite structure with Si and Mg impurities

Transmission electron microscopy (TEM) and molecular simulation studies of traces of chemical elements such as Mg, Si, and OH in the hydroxylapatite (CaHAP) crystal structure obtained from the sand dollar were carried out. Two different types of CaHAP crystal morphologies in the samples synthesized by the hydrothermal method used were observed. Reflections with regular intensity in the experimental electron diffraction patterns obtained from these morphologies were observed. However, when these results were compared with a simulated electron diffraction pattern (which was obtained using the crystalline structure proposed for the hydroxylapatite) some forbidden reflections in the experimental pattern were observed. Then, in order to reproduce the experimental patterns Si and Mg atoms in the crystalline lattice were introduced. These elements in the elemental chemical analysis carried out by X-ray energy dispersive spectroscopy (EDS) in the typical CaHAP morphologies were detected. The positions of these atoms in the asymmetric unit were obtained using molecular simulation and during the relaxation process, the structure did not show changes in the lattice parameters. Subsequently, the crystalline structure was reproduced and matched the electron diffraction patterns simulated resulting in the experimental electron diffraction pattern. Experimental and simulated X-ray diffraction spectra were also matched.     

Investigations on humidity sensing of nanostructured tin oxide synthesised via mechanochemical method

In this article, nanocrystalline tin oxide powder was prepared by a mechanochemical method. The synthesised powder was characterised using X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD shows the crystalline nature of the synthesised material. The crystallite size was estimated using Debye–Scherrer equation and its minimum value was 9?nm. Surface morphologies of the sensing pellets were investigated using SEM. Pellets as well as thick films were used as sensing elements for humidity sensing measurement. Thick film was prepared on alumina substrate using screen printing technique. Solid-state pellets as well as films were subjected to humidity-sensing measurements in a specially designed humidity chamber. Variations in resistance with relative humidity (%RH) were measured. The effects of annealing on the surface morphologies as well as on the sensitivity of the sensor were also investigated. Hysteresis and ageing effects on experimental results were found 60% and 64%, respectively, for the sensing element prepared after annealing at 600°C.     

The morphology-dependent photocatalysis for rhodamine B degradation over Bi2WO6 hierarchical nanostructure

In this paper, the nanostructured Bi2WO6 with different hierarchical morphologies was synthesized via a warmly hydrothermal route. The structure and morphology of the as-prepared Bi2WO6 products were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), UV-vis absorption spectroscopy (UV-Vis) and N2-sorption analysis. The photocatalytic efficiency of Bi2WO6 was investigated by photodegradation of rhodamine B (RhB) under visible-light irradiation. The present work demonstrated that Bi2WO6 with four different hierarchical structures was effective visible-light-driven photocatalytic functional material for environmental purification. Moreover, the nest-like Bi2WO6 exhibited superior photocatalytic effects on rhodamine B degradation compared with other three Bi2WO6 morphologies. The excellent catalytic effect of the nest-like Bi2WO6 was attributed to its unique structural property and large surface area. The relationship between morphology and photocatalytic performance was discussed in detail. The photocatalytic mechanism for the degradation of RhB was also investigated, which revealed the important role of morphology in improving the photocatalyitc activities of Bi2WO6.     

Growth of β-FeSi2 thin films on silicon (100) substrate for different annealing times by pulsed laser deposition

Single-phase β-FeSi₂ films were fabricated on silicon (100) substrates by pulsed laser deposition (PLD) technique and post-annealing process. The X-ray diffraction (XRD) showed that the diffraction intensity reached a certain threshold and then decreased with the increase of annealing time. The scanning electron microscopy (SEM) observations revealed surface morphologies of the films for different annealing times. The optimal photoluminescence (PL) of the films was obtained after 9 h annealing process. Based upon all the experimental results, it was found that the luminous properties were associated with the crystalline quality and surface morphologies.