纳米晶锌铁氧体的聚丙烯酰胺凝胶法制备、表征及其电磁性能

采用聚丙烯酰胺凝胶法合成了尖晶石型锌铁氧体（ZnFe2O4）,采用差分扫描-热重同步分析仪（DSC-TG）,红外光谱（FT-IR）,X射线衍射（XRD）,透射电镜（TEM）和波导法对干凝胶和产物进行了表征．红外光谱显示当煅烧温度从500℃升高到700℃时,铁-氧（FPO）键的特征吸收峰从541cm^-1移动到566cm^-1;XRD表明干凝胶为无定形态,在煅烧温度为500℃、煅烧时间为2h时,凝胶形成纯相的尖晶石型纳米晶ZnFe2O4;由透射电镜可知煅烧温度为500℃、600℃和700℃时,粉体的平均粒径分别为15nm、35nm和60nm;纳米晶体ZnFe2O4在8．2～12．4GHz的测试频率范围内具有介电损耗和磁损耗随着热处理温度的升高,介电常数、介电损耗、磁导率和磁损耗明显增大．     

堇青石-氧化锆红外辐射复合粉体的制备

为获得具有高红外辐射性能的粉体,以堇青石颗粒为基体,采用液相共沉淀法,用氧化锆前驱体包覆堇青石基体,煅烧后得到堇青石-氧化锆红外辐射复合粉体;对制备的复合粉体进行热分析、物相分析及形貌分析,并测试其红外辐射性能。结果表明,利用非均匀形核可将氧化锆前驱体包覆于堇青石颗粒表面,氧化锆结晶温度在800～900℃之间,900℃煅烧后得到的氧化锆晶粒尺寸约为8 nm;当在一定初始溶液浓度范围内改变反应物的用量时,可以控制氧化锆的包覆量并且避免其自发团聚;通过氧化锆纳米颗粒包覆的工艺可以提高堇青石粉体在3～5μm波段的红外辐射性能,当氧化锆包覆质量分数为21.11%时,复合粉体具有最佳的红外辐射性能。     

聚合物包覆热分解法制备纳米氧化锌的工艺研究

采用聚合物包覆热分解法化学工艺制备了纳米氧化锌，对其工艺进行系统的比较研究，对所得粉体进行XRD与SEM表征。发现利用该工艺所得粉体为六方晶系纤锌矿结构（空间群为P63mc）的纳米氧化锌。该方法制备的氧化锌衍射峰尖锐，表明此种方法合成的氧化锌结晶程度高。所得的氧化锌粉体XRD图谱中没有杂质衍射峰，说明产物纯度都很高。产品SEM表征结果显示了此工艺产物在形貌方面的高度一致性——为菊花状氧化锌纳米杆团簇，对产物形貌形成的原因做了探讨。     

纳米氧化锌-煅烧高岭土复合材料的制备

以煅烧高岭土和纳米氧化锌为主要原料,用水解沉淀法在煅烧高岭土表面包覆纳米氧化锌,制备一种无机复合型抗紫外材料;采用分光光度计分别测定在波长325、350、375、400nm紫外光下复合材料的紫外光吸光度。结果表明:反应温度、氧化锌包覆量、改性时间、改性剂滴加速度、矿浆浓度、煅烧温度等对纳米氧化锌-煅烧高岭土复合粉体材料的紫外光吸收性能有重要影响。在制备条件为:氧化锌包覆量为8%、反应温度为90℃、改性时间为10min、改性剂滴加速度为3mL/min、矿浆中m(水)∶m(煅烧高岭土)=10∶1、煅烧温度为400℃时,所制备的纳米氧化锌-煅烧高岭土复合粉体材料的紫外光吸收性能较好。     

聚合物包覆热分解法制备纳米氧化锌的工艺研究

采用聚合物包覆热分解法化学工艺制备了纳米氧化锌，对其工艺进行系统的比较研究，对所得粉体进行XRD与SEM表征。发现利用该工艺所得粉体为六方晶系纤锌矿结构（空间群为P63mc）的纳米氧化锌。该方法制备的氧化锌衍射峰尖锐，表明此种方法合成的氧化锌结晶程度高。所得的氧化锌粉体XRD图谱中没有杂质衍射峰，说明产物纯度都很高。产品SEM表征结果显示了此工艺产物在形貌方面的高度一致性—为菊花状氧化锌纳米杆团簇，文中对产物形貌形成的原因做了详细的探讨。     

油溶性二氧化钛纳米颗粒的溶剂热合成研究

以环己烷为溶剂,正钛酸四丁酯（TnBT）水解后的产物为前驱及十二胺（DDA）为表面活性物质,用溶剂热法合成了粒径小、在油相中分散均匀的二氧化钛纳米颗粒,采用X射线衍射仪（XRD）、透射电子显微镜（TEM）、傅里叶红外仪（FT—IR）对产物进行表征,结果表明,产物为锐钛矿,粒径为7．9—20．4nm,产物中有胺基（-NH2）峰,证明DDA吸附在颗粒表面。文章还对TiO2纳米颗粒合成的机理进行了探讨。     

AZO中空纳米纤维的制备及性能

中空纳米纤维因其比表面积大、密度小等特性近年来备受关注。通过静电纺丝制得聚乙烯醇(PVA)纳米纤维,并采用水热合成法在经热处理的PVA纳米纤维表面包覆一层锌铝氢氧化物,再经高温煅烧处理成功制得掺杂铝元素的氧化锌(AZO)中空纳米纤维。通过扫描电镜、热重分析仪进行测试表征,结果表明所得产物具有明显的中空结构,并对甲基橙有光催化降解性能。     

AZO@C柔性纳米纤维的制备与性能

以聚乙烯醇(PVA)为原料,成功制备了新型掺铝氧化锌包覆碳结构(AZO@C)的柔性纳米纤维。首先通过静电纺丝制备PVA初生纳米纤维,经过热处理工艺提高纳米纤维的耐水性,然后采用水热合成法在其表面包覆一层锌铝氢氧化物,再经过在500℃高温条件下烧结,PVA表面包覆的锌铝氢氧化物发生脱水反应形成致密的掺铝氧化锌(AZO)纳米粒子,同时PVA纳米纤维在高温煅烧中被炭化,形成一种新型AZO@C纳米复合材料。采用红外光谱(FT-IR)、热重分析仪(TGA)、扫描电镜(SEM)等对纳米纤维结构与性能进行测试及表征,AZO@C纳米纤维的平均直径为(320±45)nm。并通过太阳光下降解甲基橙实验证明了AZO@C柔性纳米纤维的光催化降解性能。     

微乳液化学剪裁制备纳米钛酸钡和二氧化钛

以钛酸丁酯、氢氧化钡和正己醇制备凝胶,用吐温-80/正已醇／环己烷／水制成w／O型微乳液在25℃下进行化学剪裁,将前驱物在550℃下煅烧,分别制备出了纳米钛酸钡和纳米二氧化钛．对产物进行X-射线粉末衍射（XRD）、透射电镜（TEM）、红外（IR）和差热（DTA）分析,研究了煅烧温度对BaTi03和Ti02纳米质点粒径和组成的影响．结果表明,最好的煅烧温度是550℃．所得纳米钛酸钡为具有较好晶型的六方晶体,粒径在30～42nm之间,钡钛摩尔比为1：1;纳米二氧化钛为单一的锐钛矿型八面体结构,平均粒径小于50nm．实验表明,通过凝胶．微乳液法合成的纳米物质可以有效地减少团聚,控制微粒的组成和粒径,且操作简单,成本低．     

一种制备ZnO纳米颗粒的新方法

提出了一种制备ZnO纳米颗粒的新方法。在金属钠的液氨溶液中还原硝酸锌,所形成的金属Zn自然氧化而制得ZnO颗粒。为了研究表面修饰对产物形貌、粒径和性能的影响,制备了十二烷基磺酸钠（SDS）修饰的ZnO纳米颗粒。采用X射线粉末衍射仪（XRD）、透射电子显微镜（TEM）、傅立叶变换红外光谱仪（FT-IR）、热重及差热分析仪（TG-DTA）等手段对产物进行了表征。结果表明采用该方法可制得具有六方纤锌矿结构的ZnO颗粒,未修饰ZnO颗粒团聚较为严重;修饰的ZnO纳米颗粒呈棒状,分散较好。红外和热分析表明SDS修饰在了ZnO纳米颗粒表面。测试了所制备ZnO颗粒的紫外可见吸收（UV-Vis）和光致发光（PL）谱,均出现了ZnO的特征谱带。提出的方法也适用于制备其它金属或氧化物纳米材料。     

Rapid synthesis, characterization and optical properties of TiO2 coated ZnO nanocomposite particles by a novel microwave irradiation method

A novel and rapid microwave method was used to prepare TiO₂ coated ZnO nanocomposite particles. The resulted particles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). Results show that ZnO nanoparticles were coated with 6-10 nm amorphous TiO₂ layers. In addition, zeta potential analysis demonstrated the presence of TiO₂ layer on the surface of ZnO nanoparticles. Photoluminescence (PL) spectroscopy and UV-visible spectroscopy were used to investigate the optical properties of the nanoparticles. Compared to uncoated ZnO nanoparticles, the TiO₂ coated ZnO nanoparticles showed enhanced UV emission. The UV-visible diffuse reflectance study revealed the significant UV shielding characteristics of the nanocomposite particles. Moreover, amorphous TiO₂ coating effectively reduced the photocatalytic activity of ZnO nanoparticles as evidenced by the photodegradation of Orange G with uncoated and TiO₂ coated ZnO nanoparticles under UV radiation.     

基于PEG修饰的ZnO量子点光学特性研究

采用溶胶-凝胶法制备了ZnO量子点, 并采用有机高分子试剂PEG(聚乙二醇, M_w=2000)对其表面进行修饰。借助X射线衍射分析、傅立叶红外光谱、光致发光谱和透射显微镜等测试方法, 研究了PEG表面修饰对ZnO量子点结构和光学性能的影响规律。研究表明, 混合加入的PEG聚合物能够成功地包覆在ZnO量子点表面, 但没有改变量子点的晶体结构, 经PEG表面修饰后的ZnO量子点尺寸变小, 稳定性增强, 分散更均匀。同时经PEG修饰的ZnO量子点在400~500 nm波长区域缺陷态发射峰明显减弱, 表明采用PEG来改善ZnO量子点表面缺陷结构具有良好效果。     

The structure and photoluminescence properties of ZnO/SiC multilayer film on Si substrate

ZnO/SiC multilayer film has been fabricated on a Si (111) substrate with a silicon carbide (SiC) buffer layer using the RF (radio frequency)-magnetron technique with targets of a ceramic polycrystalline zinc oxide (ZnO) and a composite target of pure C plate with attached Si chips on the surface. The as-deposited films were annealed at a temperature range of 600–1000°C under nitrogen atmosphere. The structure and photoluminescence (PL) properties of the samples were measured using X-ray diffractometry (XRD), Fourier transform infrared (FTIR) spectroscopy and PL spectrophotometry. By increasing the annealing temperature to 800°C, it is found that all the ZnO peaks have the strongest intensities, and the crystallinity of ZnO is more consistent on the SiC buffer layer. Further increase of the annealing temperature allows the ZnO and SiC layers to penetrate one another, which makes the interface between ZnO and SiC layer become more and more complicated, thus reduces the crystallinities of ZnO and SiC. The PL properties of a ZnO/SiC multilayer are investigated in detail. It is discovered that the PL intensities of these bands reach their maximum after being annealed at 800°C. The PL peaks shift with an increase in the annealing temperature, which is due to the ZnO and SiC layers penetrating reciprocally. This makes the interface more impacted and complicated, which induces band structure deformation resulting from lattice deformation.     

水热法一步合成纳米/微米级ZnO球

采用水热法在较低的温度(160℃)下一步合成了高纯的六方相ZnO纳米/微米球,它们是由纳米颗粒聚合而成的.讨论其生长机制发现,在这个合成体系中,H2O起到了非常关键的作用.X射线衍射(XRD)谱中各衍射峰清晰且尖锐,说明ZnO结晶性能良好.扫描电子显微镜(SEM)、场发射扫描电子显微镜(FESEM)和透射电子显微镜(TEM)照片表明,在其他条件固定的情况下,可以通过调节三乙醇胺和水的体积比有效地控制ZnO球的尺寸和形状.紫外可见吸收光谱的吸收峰随着ZnO球直径的增加出现红移现象.     

Effect of inorganic-organic composite coating on the dispersion of silicon carbide nanoparticles in non-aqueous medium

In order to disperse silicon carbide (SiC) nanoparticles homogeneously in a non-aqueous medium, the surface of SiC nanoparticles needs to be modified via surface organic functionalization. A method of SiC nanoparticle surface modification by grafting of polyacetals via inorganic-organic composite coating was developed. The resulting graft percentage of up to 10.5% was much higher than that of direct grafting. The inorganic-organic composite coating on a SiC nanoparticle surface led to an almost complete decomposition of the secondary structure of the agglomerates and the formation of the primary structure. Dispersibility of the modified version was studied by using a transmission electron microscope (TEM) and size distribution analyser. The sedimentation experiments showed that the coated SiC nanoparticles exhibited good suspension stability in butanone. The composition of the inorganic-organic composite coating on the SiC nanoparticles was investigated by energy dispersive x-ray analyses (EDX), hydrogen nuclear magnetic resonance ((1)H NMR) and Fourier-transformed infrared spectroscopy (FT-IR). This work provides a novel concept of surface grafting modification for non-oxide nanoparticles to improve their dispersibility in non-aqueous medium.     

水溶性PEO—PPO—PEO包裹Fe3O4纳米微粒的可控制备

以聚氧乙烯-聚氧丙烯-聚氧乙烯三嵌段共聚物（PEO—PPO—PEO）作表面活性剂,采用纳米微乳液法还原Fe（Ⅱ）-乙酰丙酮化合物（Fe^Ⅱ（acac）2）,制备粒径可控、单分散、水溶性Fe3O4纳米微粒,并进行了相关的表征测试。从傅里叶变换红外光谱（FTIR）中可以看出,共聚物PEO—PPO—PEO包裹在Fe3O4纳米微粒表面;透射电镜（TEM）显示纳米颗粒分散性好,呈球形;高斯拟合表明,不同物料配比合成的Fe3O4粒子大小、粒径分布不同;振动样品磁强计（VSM）测试说明,Fe3O4纳米颗粒室温下为超顺磁性或软铁磁性。由于PEO-PPO—PEO具有亲水性,PEO—PPO—PEO包裹的Fe3O4纳米微粒不用进一步处理即可转移到水相中,在生物和医学领域具有重要的潜在应用价值。     

非水溶胶凝胶法制备ZnO/Al2O3复合纳米颗粒

以无水ZnCl2和无水AlCl3为前躯体,丙酮为溶剂,油酸为氧供体,采用非水溶胶凝胶法制备ZnO/Al2O3复合纳米颗粒,通过X-ray衍射（XRD）、红外光谱（IR）、透射电镜（TEM）和紫外可见分光光度计对制备的颗粒进行表征,结果表明,颗粒为无定形态的ZnO/Al2O3复合纳米颗粒,平均粒径为61nm,呈球形单分散状态,具有良好的油溶性,能均匀稳定地分散在20#机械油中。     

Blue luminescence from carbon modified ZnO nanoparticles

In this work, a novel method was used to prepare carbon modified ZnO nanoparticles. The nanoparticles were coated with a layer of poly(methyl methacrylate) by γ radiation firstly, and then the coated nanoparticles were annealed in air. The polymer was burned and carbon was left on the surface of ZnO nanoparticles. A stable blue luminescence peak (~420 nm) can be observed for the carbon modified ZnO nanoparticles. The carbon modified ZnO nanoparticles were also investigated by X-ray photoelectron spectroscopy. The origin of the blue emission was discussed. The blue PL is related to the left carbon. This novel method also can be used to prepare other carbon modified nanoparticles.     

Performance of Eu2O3 coated ZnO nanoparticles-based DSSC

To provide an inherent energy barrier between the electrode and electrolyte interface, the surface of the ZnO nanoparticles has been modified by Eu₂O₃ layer. The synthesis of ZnO, Eu₂O₃ coated ZnO nanoparticles have been carried out by chemical precipitation method and solvothermal treatment. The synthesized samples were characterized by XRD and the diffraction plane (222) of Eu₂O₃ detected, demonstrating the existence of Eu₂O₃ on the surface of ZnO, which is further verified using energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy. The strong quenching in photoluminescence emission, in case of Eu₂O₃/ZnO nanoparticles, has been attributed to the decrease in recombination rate of photo-generated electron–hole pairs. Compared to ZnO electrodes, Eu₂O₃ coated ZnO electrodes adsorbed more dye. The photoelectrochemical properties of the Eu₂O₃/ZnO electrodes have been found to improve and the energy conversion efficiency increase from 0.44 to 1.45 % under the illumination of simulated light of 100 mW/cm².     

Fast one-step synthesis of ZnO sub-microspheres in PEG200

ZnO sub-microspheres were synthesized via a new, simple, and one-step method by using zinc acetate dihydrate as a precursor and PEG200 as a solvent and modifier. The effect of temperature (160–210 °C) on the crystallization, surface morphology, and luminescence properties of ZnO spheres was investigated using different characterization techniques, including X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, UV–Vis spectroscopy, and room temperature photoluminescence. The results show that the ZnO crystal has a hexagonal wurtzite structure. The products have monodispersed spherical morphology with diameters in the range of 200–600 nm. They have intensive UV emission peaks at ~380 nm and relatively weak and broad green peaks at ~550 nm. The PEG200 molecules adsorb on the surface of ZnO spheres. On the basis of the experimental results, a mechanism was proposed to elucidate the formation of ZnO sub-micron spheres.