纳米结构氧化铁棒束的制备、表征及光学性质

以三氯化铁(FeCl3·6H2O)和氨三乙酸(N(CH2COOH)3)为主要原料,在160℃反应12h得到了空心管状的白色前驱体,再经500℃煅烧2h得到了纳米结构氧化铁棒束.通过热重分析(TG)、光学显微镜、X射线衍射(XRD)、扫描电子显微镜(SEM)、红外光谱(FT-IR)、紫外-可见光谱(UV-Vis)对所得产物进行了表征.结果表明:所得白色前驱体经500℃煅烧后全部转化为六方相的氧化铁(α-Fe2O3),形貌为含微孔结构的棒束,直径约为2μm,其结构单元为含微孔结构的纳米棒,这些棒的直径为30～50 nm,长度约16μm;紫外数据表明所得氧化铁棒束的最大吸收波长为546nm,带宽吸收约在685 nm处,发生红移.     

氧化锌纳米粒子的合成及其表面功能化修饰

以三甘醇(TEG)为溶剂,高温热分解乙酰丙酮锌合成了氧化锌纳米粒子.为改善氧化锌纳米粒子表面性能和生物应用性能,分别用硅烷偶联剂(KH550)和聚酰胺-胺(PAMAM)进行表面修饰,在氧化锌纳米粒子表面接枝了-NH2活性官能团.分别采用X射线衍射仪(XRD)、透射电镜(TEM)、红外光谱(FT-IR)、X射线光电子能谱、动态光散射(DSL)和紫外可见分光光度计(UV-Vis)对样品进行了表征测试.XRD结果表明纳米氧化锌的平均晶粒尺寸为10 nm,并具有较好的结晶性.TEM观察表明,其形貌为颗粒状和小晶粒团聚成的球状粒子.FT-IR、XPS、DSL和Zeta电位测试结果表明氨基官能团成功修饰在氧化锌纳米粒子表面,增强了粒子的表面功能.UV-Vis光谱表明,氨基活性基团修饰后的纳米氧化锌仍然具有较强紫外带隙吸收.     

聚乙烯醇对ZnO纳米棒结构和光学性能的影响

以六水硝酸锌为锌源,聚乙烯醇(PVA)为分散剂,制备了纳米氧化锌(ZnO).利用X射线衍射(XRD)和电子扫描电镜(SEM)对氧化锌的晶体结构、形貌和尺寸进行了表征.利用吸收光谱对氧化锌的吸收率进行了测量.结果表明,所制备的氧化锌属于六方纤锌矿单晶结构,呈棒状结构.通过改变PVA含量,氧化锌纳米棒的长度可以从400nm到2μm可调.吸收光谱表明,随着PVA含量增加,吸收光谱发生红移.讨论了PVA作用下氧化锌纳米棒的形成机理.     

衬底放置方式对ZnO阵列形貌的影响

ZnO纳米棒阵列通过两步化学法制备,首先通过水热法在ITO衬底上制备ZnO晶种,然后把有ZnO晶种的ITO衬底垂直放入以氯化锌和氨水为溶剂的pH值为11的溶液,在85℃恒温条件下生长2h,然后在600 ℃对其进行退火处理,就得到了在ITO衬底上生长的ZnO纳米棒阵列.利用X射线衍射(XRD)、扫描电子显微镜(SEM)、高分辨透射电子显微镜(HRTEM)、紫外可见分光光度计和光致发光谱仪(PL)对样品的晶体结构、形貌和光学性能进行了表征.结果表明制备的高密度棒状ZnO纳米阵列是垂直生长在ITO衬底上,纳米棒的直径大约为150nm,长约1μm,纤锌矿ZnO纳米棒沿着[0002]方向一致生长;ZnO纳米棒阵列在波长为300 ～400 nm处出现了很强的紫外吸收峰;ZnO纳米棒阵列的光致发光光谱在380 nm左右有一个极强的紫外发光峰.研究了衬底放置方式对ZnO晶种形貌和光学性能的影响.最后通过对棒状ZnO纳米阵列形成过程中可能涉及到的化学反应以及形成机理做了简单的分析.     

纳米ZnO的形态控制及其发光性能

以醋酸锌为原料,以聚合物和表面活性剂为添加剂,水热法合成了两种新型的纳米ZnO结构.并采用X射线衍射(XRD)、透射电镜(TEM)和高分辨透射电镜(HRTEM)以及光致发光光谱(PL)等测试方法对所得产物形貌和光学性能进行了研究,并对对两种纳米形态的形成机理进行了初步的探讨.结果表明:所得产物为六角纤锌矿型氧化锌纳米晶,分散性良好,形貌为枣核状,而这种枣核状的粒子是由众多短棒状粒子取向生长而形成的.升高温度,则得到了直径约100 nm,长约2 μm 的两头尖的纳米棒,棒的表面依附生长了针状颗粒.     

ZnO/ZnS复合材料的制备、表征及其光学性能研究

通过简便的两步水热法成功合成了ZnO/ZnS复合材料,通过X射线衍射(XRD)、扫描电镜(SEM)、透射电子显微镜(TEM)、荧光光谱(FTR)和紫外-可见分光光度计(UV-vis)对所得产物进行表征.结果表明:复合物由大量针状的六方纤锌矿氧化锌结构和立方相硫化锌纳米粒子组成,并且ZnS纳米粒子成功的组装在针状ZnO纳米单体的表面,成功合成了ZnO/ZnS复合材料.光学性能研究表明,复合物ZnO/ZnS比ZnO单体表现出更为优异的光致发光性及紫外吸收性能.     

气相阳离子交换法制备CoO纳米棒及其光学性能

以水热法合成的ZnO纳米棒为模板,采用气相阳离子交换法制备形貌可控、结晶性良好的CoO纳米棒.通过X射线衍射(X RD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线能谱(EDS)和紫外-可见吸收光谱仪(UV-vis)对所得产物的物相组成、形貌、化学成分和光学性能进行表征与测试.结果表明,所得产物为立方相CoO纳米棒,直径在100 ～ 150 nm之间,具有较宽的紫外-可见光吸收范围,通过计算得其光学带隙为2.70 eV.此外,能谱分析线扫描探讨阳离子交换机理的研究表明,高温促使Co2+逐步取代Zn2+,导致ZnO纳米棒完全转变为CoO纳米棒.     

Eu2O2S的一步溶剂热法合成、表征及性能研究

以六水硝酸铕、无水乙醇、乙二胺和升华硫为实验原料,采用一步溶剂热法成功合成了Eu2O2S.通过X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、场发射扫描电子显微镜(FE-SEM)和紫外-可见吸收光谱(UV-vis absorption)对合成产物进行了表征.XRD和FT-IR表明Eu3+离子与升华硫的摩尔比m、合成温度和合成时间对产物的物相组成有显著的影响.FE-SEM照片显示,随着反应条件的改变,产物形貌由类球状转变为虾片状,对应的颗粒尺寸由20 nm增加至200 nm.UV-vis表明Eu2O2S在以290 nm为中心的紫外光区存在宽带吸收,其禁带宽度约为4.3 eV.     

CuInS2量子点敏化ZnO基光阳极的制备与性能研究

采用两步法在导电玻璃(FTO)基板上制备纯氧化锌(ZnO)纳米棒和钇掺杂的氧化锌(ZnO∶Y)纳米棒,采用连续离子层吸附反应法(SILAR)在所制备的ZnO及ZnO∶Y纳米棒上沉积CuInS₂量子点制备ZnO/CuInS₂和ZnO∶Y/CuInS₂光阳极。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、电子探针能谱仪(EDS)、紫外-可见分光光度计(UV-Vis)、电流密度-电压(J-V)曲线等技术手段对不同光阳极样品的晶相结构、微观形貌、化学组成、光吸收性能和太阳电池性能进行了表征。实验结果表明:所制备的ZnO纳米棒和ZnO∶Y纳米棒为六方纤锌矿结构。CuInS₂量子点敏化的ZnO纳米棒薄膜的光学带隙从3.22 eV减小为2.98 eV。CuInS₂量子点敏化ZnO∶Y太阳能电池的短路电流密度和光电转换效率比未掺杂的ZnO纳米棒组装的太阳能电池分别提高了6.5%和50.4%。     

钇掺杂多孔结构氧化锌纳米棒的制备与性能研究

采用两步法在二氧化锡掺氟(SnO2:F,FTO)导电玻璃基板上制备出钇(Y)掺杂多孔结构氧化锌(ZnO)纳米棒,首先利用浸渍-提拉法在FTO导电玻璃基板上制备ZnO晶种层,然后利用水热法在ZnO晶种层上生长Y掺杂ZnO纳米棒.研究了不同浓度Y掺杂ZnO纳米棒的晶相结构、微观形貌、化学组成及光学性能.实验结果表明:所制备的Y掺杂ZnO纳米棒为沿c轴择优取向生长的六方纤锌矿结构,随着Y掺杂浓度的增加,ZnO纳米棒(002)衍射峰强度先增大后减小,纳米棒的平均长度由1.3μm增加到2.6μm.ZnO纳米棒的形貌由锥状结构向柱状结构演化,纳米棒侧面的孔洞分布密度增加.所制备的Y掺杂ZnO纳米棒具有一个较弱的紫外发光峰和一个较强的宽可见发光峰.所制备样品的光学带隙随着Y掺杂浓度的增加而减小,其光学带隙在3.29～3.21 eV之间变化.利用Y掺杂ZnO纳米棒作为量子点敏化太阳能电池的光阳极可极大提高太阳电池的光电转换效率.     

Co掺杂ZnO薄膜的湿化学法制备及其光致发光光谱

采用湿化学法在Si衬底上生长了纳米棒结构的Co掺杂ZnO薄膜,并研究了掺杂浓度对生成样品结构和性能的影响.研究表明这种湿化学法成本低廉、收益高、重复性良好.样品的XRD结果表明掺杂的ZnO没有出现杂相.SEM结果表明掺杂样品是由ZnO纳米棒团簇结构组成,且团簇的密度随着Co掺杂浓度的增大而增大.薄膜的光致发光光谱结果表明Co掺杂导致薄膜的带隙发生红移,同时也证明了Co原子有效地进入了ZnO晶格.     

铟镓共掺杂对n-ZnO纳米棒/p-GaN异质结生长行为和光电性能的影响

利用低温水热法在p-GaN薄膜上生长了铟(In)和镓(Ga)共掺杂的ZnO纳米棒。X射线衍射(XRD)、X射线光电子能谱(XPS)和X射线能量色谱仪(EDS)结果表明,In和Ga已固溶到ZnO晶格中。扫描电子显微镜(SEM)结果表明, ZnO纳米棒具有良好的c轴取向性,随着In和Ga共掺杂浓度的增加,纳米棒的直径减小,密度增加。XRD结果表明,In和Ga共掺杂引起ZnO晶格常数增大,导致(002)衍射峰向低角度方向偏移。同时,ZnO的光学性质受到In和Ga共掺杂的影响。与纯ZnO相比, 共掺杂ZnO纳米棒的紫外发射峰都出现轻微红移,这是表面共振和带隙重整效应综合作用的结果。I-V特性曲线表明,随着In和Ga共掺杂浓度的增加,n-ZnO纳米棒/p-GaN异质结具有更好的导电性。     

Low temperature hydrothermal growth and optical properties of ZnO nanorods

Well‐faceted hexagonal ZnO nanorods have been synthesized by a simple hydrothermal method at relative low temperature (90°C) without any catalysts or templates. Zinc oxide (ZnO) nanorods were grown in an aqueous solution that contained Zinc chloride (ZnCl₂, Aldrich, purity 98%) and ammonia (25%). Most of the ZnO nanorods show the perfect hexagonal cross section and well‐faceted top and side surfaces. The diameter of ZnO nanorods decreased with the reaction time prolonging. The samples have been characterized by X‐ray powder diffraction (XRD) and scanning electron microscopy (SEM) measurement. XRD pattern confirmed that the as‐prepared ZnO was the single‐phase wurtzite structure formation. SEM results showed that the samples were rod textures. The surface‐related optical properties have been investigated by photoluminescence (PL) spectrum and Raman spectrum. Photoluminescence measurements showed each spectrum consists of a weak band ultraviolet (UV) band and a relatively broad visible light emission peak for the samples grown at different time. It has been found that the green emission in Raman measurement may be related to surface states. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

反向微乳液法合成ZnO纳米棒及其生长机理研究

采用对比实验法,利用表面活性剂CTAB、正己烷、异丙醇和Zn2水溶液组成的反向微乳液体系制备了ZnO纳米棒,探讨了组成及工艺因素对纳米棒形貌影响,采用XRD和SEM分析技术对实验产物物相结构及形貌进行了表征.结果表明,通过调控Zn2+水溶液的浓度、水相含量与表面活性剂加入量的物质的量比(W)能更有效的控制ZnO纳米棒的长径比.     

Hydrothermal synthesis and characterization of micro/nanostructured ZnSn(OH)6/ZnO composite architectures

Micro/nanostructured ZnSn(OH)₆/ZnO composite architectures were synthesized through a simple one‐step hydrothermal method. Phase structure and morphology of the products were characterized by using X‐ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). ZnSn(OH)₆ microcubes and ZnO nanorods with uniform size were interconnected to form the micro/nanostructured architectures. ZnO nanorods preferentially grow at edges and corners of the microcubes. Morphology of the products was susceptible to concentration of the reactants. With increasing reactant concentration, the ZnO nanorods grown on the surfaces of ZnSn(OH)₆ microcubes disappeared. Meanwhile, the smooth surfaces of the ZnSn(OH)₆ microcubes become coarsened and were etched to spherical outlines. Growth mechanism of the micro/nanostructured ZnSn(OH)₆/ZnO composite architectures was discussed and thermal decomposition properties of the micro/nanostructured ZnSn(OH)₆/ZnO composite architectures at high temperature were examined. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Effect of growth temperature on the structure and optical properties of ZnO nanorod arrays grown on ITO substrate

ZnO nanorod arrays have been successfully prepared on ITO substrate by a chemical‐bath deposition method at different growth temperatures. The influence of the growth temperature on the morphology and microstructure of the ZnO nanorods was investigated by scanning electron microscopy (SEM) and X‐ray diffraction (XRD). The results showed that the diameter of the ZnO nanorods decreased and the size of the nanocrystals increased with increasing growth temperature. Optical absorption measurements showed the absorption band edge has shifted to a lower‐energy region due to the quantum size effect. Green emission and UV emission bands were observed and they are found to be temperature dependent, which indicates that the deep‐level emission and band‐edge emission of ZnO nanorods is closely related to the rod diameter, and the related mechanism is discussed.     

Synthesis and growth mechanism of ZnO rod‐like nanostructures by a microwave‐assisted low‐temperature aqueous solution route

A zinc oxide (ZnO) nanoarray (rod‐like nanostructure) was successfully synthesized through a low‐temperature aqueous solution and microwave‐assisted synthesis using zinc nitrate hexahydrate (Zn(NO₃)₂·6H₂O) and hexamethylenetetramine (HMTA) as raw materials, and using FTO glass as substrate. The effects of parameters in the preparation process, such as solution concentration, reaction temperature and microwave power, on the morphology and microstructure of ZnO nanoarray were studied. Phase structure and morphology of the products were characterized by X‐ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The results indicated that hexagonal wurtzite structure ZnO nanoarray with good crystallization could be prepared through a low‐temperature solution method. When the concentration of the mixed solution was 0.05 M, the reaction temperature was 95 °C, and the reaction time was 4 h, high‐density ZnO regular nanorods of 200 nm diameter were obtained. A possible mechanism with different synthesis methods and the influence of microwave processing are also proposed in this paper.     

Synthesis of ZnO nanorods by the thermal reduction process of a mixture of ZnO and Al powder

Single‐crystalline Zinc oxide (ZnO) nanorods were firstly synthesized on gold‐coated Si substrate via a simple thermal reduction method from the mixture of ZnO and Al powder. The growth process was carried out in a quartz tube at different temperature (550‐700 °C) and at different oxygen partial pressure. Their structure properties were investigated by X‐ray diffraction (XRD), scanning electron microscope (SEM), X‐ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The length of the as‐prepared ZnO nanorods was up to several micrometers and their diameters were about 130 nm. The X‐ray diffraction patterns, transmission electron microscopic images, and selective area electron diffraction patterns indicate that the one‐dimensional ZnO nanorods are a pure Single‐crystal and preferentially oriented in the [0001] direction. The reaction mechanism of ZnO nanorods was proposed on the basis of experimental data. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)