Cr掺杂ZnO纳米纤维的低温氧敏性能

采用静电纺丝法制备了Cr掺杂ZnO纳米纤维,通过DSC-TG、Raman和SEM等表征了纳米纤维的热学性质、物相和微观形貌,并测量了所制备纳米纤维的低温氧敏性能。研究了煅烧温度和Cr掺杂含量对纳米纤维低温氧敏性能的影响。结果表明:所制备的纳米纤维直径均匀,表面光滑;在600℃煅烧的1%Cr掺杂含量的ZnO纳米纤维具有最佳的低温氧敏性能,并分析了各因素的影响及其可能的机理。     

电化学沉积Mn掺杂纳米ZnO的结构和光学性质的研究

在Si衬底上用电化学沉积方法制备了Mn掺杂ZnO纳米晶X射线衍射（XRD）的研究表明,Mn离子取代Zn离子进入到 ZnO晶格中。场发射扫描电子显微镜（SEM）图像显示,ZnO纳米晶形貌的是柱状的。从光致发光谱可以看出,由于掺杂效应导致了可见发射带扩大, PL谱从122.8k到302.2k范围的拟合结果表明,Mn掺杂导致的激子结合能的降低。     

电化学沉积Mn掺杂纳米ZnO的结构和光学性质研究（英文）

在Si衬底上用电化学沉积方法制备了Mn掺杂ZnO纳米晶,X射线衍射(XRD)的研究表明,Mn离子取代Zn离子进入到ZnO晶格中。场发射扫描电子显微镜(SEM)图像显示,ZnO纳米晶形貌是柱状的。从光致发光谱可以看出,由于掺杂效应导致可见发射带扩大,PL谱从122.8 K到302.2 K范围的拟合结果表明,Mn掺杂导致激子结合能的降低。     

垂直生长于锌基底的Co掺杂ZnO纳米棒阵列显著室温铁磁性能

通过简单的水热合成法在锌片基底上一步制备了Co掺杂的ZnO纳米棒阵列。纳米棒在基底上均匀分布,取向一致,垂直于基底大面积生长。样品结构均为六方纤锌矿结构,具有高结晶质量,不含其它杂相。随着Co掺杂浓度的增加,紫外发射峰强度逐渐下降,近带隙发射峰的半峰宽也较纯ZnO变宽。拉曼光谱显示Co的掺杂使纳米棒出现了氧空位和锌填隙本征缺陷。随着Co浓度的增加这些缺陷也随之增加。掺杂纳米棒阵列的磁滞回线表明样品具有明显的铁磁特征,并有较大的矫顽力Hc~660 Oe。这种ZnO基稀磁半导体纳米棒阵列是一种在自旋电子器件中具有应用潜力的纳米材料。     

钙掺杂二氧化钛纳米纤维的制备及其光催化性能

以乙酸钙为钙源,钛酸异丙酯为钛源,采用静电纺丝和溶胶-凝胶法制备了不同Ca~(2+)掺杂浓度的Ti O_2纳米纤维光催化剂,利用XRD和SEM等手段对样品结构和形貌进行了分析和表征,研究发现Ti O_2纳米纤维主要为锐钛矿结构并含少量的金红石结构。同时,通过对水溶性罗丹明B的光降解反应,考察了Ti O_2纳米纤维催化剂的光催化活性。研究结果表明:Ca~(2+)掺杂可有效提高Ti O_2纳米纤维对水溶性罗丹明B的光催化活性,其中当Ca~(2+)为最佳掺杂浓度5 at%,Ti O_2用量为1.2×10~(-2 )g/L,紫外光照射100 min条件下,Ti O_2样品对浓度为1×10~(-5 )mol/L罗丹明B的降解率可达95%。     

垂直生长于锌基底的Co掺杂ZnO纳米棒阵列显著室温铁磁性能（英文）

通过简单的水热合成法在锌片基底上一步制备了Co掺杂的ZnO纳米棒阵列。纳米棒在基底上均匀分布,取向一致,垂直于基底大面积生长。样品结构均为六方纤锌矿结构,具有高结晶质量,不含其它杂相。随着Co掺杂浓度的增加,紫外发射峰强度逐渐下降,近带隙发射峰的半峰宽也较纯ZnO变宽。拉曼光谱显示Co的掺杂使纳米棒出现了氧空位和锌填隙本征缺陷。随着Co浓度的增加这些缺陷也随之增加。掺杂纳米棒阵列的磁滞回线表明样品具有明显的铁磁特征,并有较大的矫顽力H c=52.8 k A/m。这种ZnO基稀磁半导体纳米棒阵列是一种在自旋电子器件中具有应用潜力的纳米材料。     

铝掺杂纳米氧化锌的液相火焰燃烧合成及其导电性研究

采用液相火焰燃烧合成法制备得到了Al掺杂纳米氧化锌,该技术具有简单、连续和易于大规模产业化等优点。对合成得到的纳米ZnO进行了SEM和XRD表征,燃烧产物为直径约30~40nm的球形颗粒,为六方相结构。当掺杂浓度超过8mol%时导电氧化锌中出现立方相的ZnAl2O4尖晶石。Al掺杂纳米ZnO的导电性随着Al掺杂量的增加首先迅速提高,之后提高幅度逐渐变缓,在Al掺杂量为8.0mol%时,导电氧化锌的导电性最佳,而当掺杂量进一步增加后导电性反而有所降低。     

ZnO水热膜的形貌调控及光电性能

在硝酸锌/(NH_2)_6N_4(HMTA)溶液体系中加入浓氨水及氯化铜,采用水热法制备Cu掺杂的ZnO薄膜。研究发现,氨水和Cu~(2+)离子均可抑制ZnO纳米棒的横向生长,促进纳米棒沿c轴取向生长,增加长径比,但并未发现Cu进入ZnO晶格中。ZnO水热阵列膜的形貌可以通过同时掺杂Cu2+和加入浓氨水来改变。Cu~(2+)离子和氨水共掺杂容易导致ZnO纳米棒的弯曲及纳米棒端头的聚集,形成由纳米棒团簇组成的星星状薄膜表面。PL谱显示,该结构具有较大的氧空位缺陷浓度及比表面积,并具有一定的场发射特性,场增强因子β为5990。     

溶剂热法制备Co、Ni共掺杂ZnO纳米棒及其性能研究

采用溶剂热法制备Co、Ni共掺杂ZnO的纳米材料。样品的XRD图谱表明,不同浓度的掺杂都没有改变ZnO的晶体结构,样品均为六方纤锌矿结构;XPS结果揭示了钴和镍均以+2价离子形式存在,进一步证明了Co2+、Ni2+是以替代部分Zn2+的形式存在于晶格中;高分辨图像显示,所得样品为纳米棒结构,纳米棒长度约150 nm,直径约15 nm;mapping图像及EDS显示出Co2+、Ni2+已经掺杂成功而且在纳米棒中均匀分布;PL测试表明,Co2+、Ni2+的掺杂导致锌空位浓度的变化,从而使得紫外发光峰右移。     

PANI/Ag-TiO2纳米纤维复合材料的制备及其抗菌性能研究

采用水热法制备Ag掺杂量不同的Ag/TiO2纳米复合材料,通过原位聚合法制备PANI/Ag-TiO2纳米纤维复合材料,利用XRD、SEM、FT-IR等检测技术对复合材料的结构进行了表征。研究了光源、Ag掺杂量、不同实验菌种等因素对PANI/Ag-TiO2纳米纤维复合材料抗菌性能的影响。结果表明：在无光照射情况下,PANI/Ag-TiO2纳米纤维复合材料具有良好的抗菌性能,在长波紫外光照射情况下,抗菌性能进一步增强。在浓度1 mg/mL时,在无需光照的情况下对4种实验菌种杀菌率均达到99.99%。     

Synthesis,Characterization, and Gas Sensing Properties of Pure and Mn-doped ZnO Nanocrystalline Particles

Nanocrystalline ZnO and Mn (1 wt.%)-doped ZnO particles have been synthesized via reverse micelle method. The structural, particulate, and optical properties of the synthesized nanoparticles have been studied by XRD, TEM, UV-Vis, and PL spectroscopy. The obtained data indicate the synthesis of the pure nanoparticles structure with wurtzite structure, average particle size of 18-21 nm, and high optical quality. Gas sensing properties of the nanocrystalline ZnO and Mn-doped ZnO particles toward gasoline and ethanol vapors have been investigated at different temperatures and concentrations. The results show that the optimum working temperature of the gas sensors based on ZnO and Mn-doped ZnO particles are about 633 and 620 K toward ethanol vapor and about 560 and 608 K toward gasoline vapor, respectively. Based on the results, although Mn impurities reduce the sensitivity of the ZnO gas sensor, they cause sensor to saturate at much higher gas concentration.     

Effect of defect complex on magnetic properties of (Fe,Mn)-doped ZnO thin films

We have observed room temperature ferromagnetism in Mn-doped and (Fe, Mn)-codoped ZnO thin films grown under different oxygen partial pressures by pulsed laser deposition. The X-ray diffraction and optical transmission spectra studies demonstrate the natural incorporation of Fe and Mn cations into wurtzite ZnO lattices. The effects of transition metal doping and defects on the magnetic properties was investigated. It is found that room temperature ferromagnetism is sensitive to oxygen vacancy and Zn vacancy. The absence of ferromagnetism in pure ZnO films grown under different oxygen partial pressures reveals that the transition metal ions should also play an important role in inducing the ferromagnetism.     

Progress in Zno-based diluted magnetic semiconductors

ZnO-based diluted magnetic semiconductors (DMS) have attracted a great deal of research attention and controversy over the past decade. The initial attention was sparked by the prediction of above-room-temperature ferromagnetism in Mn-doped ZnO by T. Dietl. This was followed by a surge of reports of ferromagnetism in thin film transition metal (TM)-doped ZnO. However, reported values of magnetic moments and Curie temperatures were inconsistent, which led to controversy over the origin of the observed ferromagnetism. In this paper we review a number of TM-doped ZnO-based DMS in order to clarify which materials are likely ferromagnetic.     

Fluorescence studies of electrospun MEH-PPV/PEO nanofibers

We report a study of the fluorescence properties of the conjugated polymer poly [2-methoxy-5-(2′-ethyl hexyloxy)-p-phenylene vinylene] (MEH-PPV) and polyethylene oxide (PEO) nanofibers. MEH-PPV/PEO nanofibers with different compositions have been fabricated by the electrospinning technique. The fluorescence spectra of the nanofibers show that the emission shoulder at ∼630 nm blue-shifts ∼45 nm, whereas the main emission peak around 590 nm blue-shifts ∼15 nm with decreasing concentration of MEH-PPV in the nanofiber. In addition, confocal microscopic studies of a single MEH-PPV/PEO electrospun nanofiber indicate that the fluorescence spectra of the nanofiber do not show any polarization dependence. The results are discussed in terms of the aggregation of MEH-PPV in an inert matrix.     

Structure and photoluminescence properties of Ag-coated ZnO nano-needles

A large number of zinc oxide (ZnO) nano-needles were synthesized by thermal oxidation of pure zinc. The surfaces of ZnO nano-needles were coated with a layer of Ag by pulse electro-deposition technique. The uncoated and coated ZnO nano-needles were characterized by using the X-ray diffraction and the scanning electron microscope (SEM). The results showed that the uncoated samples were close-packed hexagonal structure, which showed needle-like morphology. Their average diameter is about 40 nm, lengths up to 5 μm. At the same time we observed that the prepared ZnO nano-needles have been coated with Ag successfully. The photoluminescence spectrums of ZnO nano-needles with Ag-coated and uncoated were analyzed, finding that the uncoated ZnO nano-needles have two fluorescence peaks at 388 nm and 470.8 nm, respectively, the relative intensity of 143.4 and 93.61; and the Ag-coated ZnO nano-needles showed a pair of strong peaks at 387.4 nm and 405.2 nm, the relative intensity of 1366 and 1305, respectively, indicating that the Ag-coated ZnO nano-needles can increase the absorption of UV light.     

Sm,Nd共掺CeO2纳米纤维电解质的制备与性能

利用静电纺丝技术制备了Sm2O3和Nd2O3共掺CeO2纳米纤维固体电解质,通过XRD、TEM和SEM等仪器对其物相和微观结构进行了表征,并利用电化学工作站测量了不同煅烧温度纳米纤维的电导率。实验结果表明不同煅烧温度下的纳米纤维均呈现立方萤石结构,400oC煅烧获得的纳米纤维电解质平均直径为402nm,晶粒尺寸约为5nm,并且其电导率最高。     

Improving color rendering index of Mn-doped ZnO nanorods on silicon-based substrate

Porous silicon pillar array(PSPA) samples which are ideal substantial materials with dominant electronic and luminescence properties were prepared by surface etching method. ZnO nanorods with or without Mn doping grown uniformly and aligned onto PSPA regardless of lattice matching show various photoluminescence(PL)properties. The doped Mn ions in ZnO nanorods were directly observed by X-ray photoelectron spectroscopy(XPS),and ZnO structures were detected by X-ray diffraction(XRD). As the doping concentration increases,XRD peaks of ZnO nanorods shift to low angle. The influences of doping Mn ions on luminescence properties of ZnO nanorods were investigated. Except for the ultraviolet(UV) PL band, the broad PL band is observed at visible region. The band could be divided into three separate bands(orange, green and red) by Lorentzian deconvolution. The intensity of orange PL band firstly increases then decreases, and then gets the maximum at the doping Mn-to-Zn molar ratio of 2.0:100.0 which is the most effective doping concentration. The green PL band is attributed to zinc vacancy of ZnO, the orange PL band to Mn ions recombination of itself, and the red PL band to oxygen vacancy of ZnO, respectively. As the Mn-doped ZnO nanorods could emit yellow green luminescence excited by UV radiation, and doped Mn ions could improve the color rendering index of the luminescence, the nanorods could be used as promising white-light emitters in the future.     

Preparation and characterization of uniform circinate aggregates of sheet ZnO nanoparticles

Uniform circinate aggregates of sheet ZnO nanoparticles with a specific surface area of 24 m2·g-1 were prepared by the direct precipitation method.The circinate aggregates were hexagonal ZnO,with the wall thickness ranging from 0.5 to 1 μm and the diameter ranging from 5 to 10 μm.The backs of the circinate aggregates were regularly arranged by numerous sheet ZnO nanoparticles with a thickness of 30-80 nm and a diameter of 300-400 nm.The precursors were aggregates of sheet Zn5(CO3)2(OH)6 nanoparticles,which were decomposed into ZnO by calcining in air in the range of 200-285℃,and the ZnO retained the similar special structure.The C2H5OH content had a significant effect on the formation of sheet ZnO.The centripetal force,the Van der Waals force,and the hydrogen bond were deduced as the driving forces of the formation of circinate.     

ZnO纳米棒的制备及光催化性能研究

采用水热法制备ZnO纳米棒。利用X射线粉末衍射(XRD)仪和透射电镜(TEM)对其结构和形貌分别进行表征,并通过紫外-可见分光光度计分析ZnO纳米棒光降解甲基紫来研究其光催化活性。结果表明,以氢氧化钠和醋酸锌为原料,聚丙烯酰胺为表面活性剂制备得到直径约26nm,长度达400nm的单晶纤锌矿结构的ZnO纳米棒。添加ZnO纳米棒光催化剂时的光降解率为70%,未加ZnO纳米棒的光降解率为30%,表明ZnO纳米棒具有很好的光催化活性。