La_(0.7)Sr_(0.3)MnO_3纳米颗粒的制备和光催化性能EI北大核心CSCD

采用聚丙烯酰胺凝胶法制备La_(0.7)Sr_(0.3)MnO_3(LSMO)纳米颗粒,用X射线衍射、扫描电镜对样品进行了表征。结果表明,分别以柠檬酸、酒石酸、醋酸、草酸、EDTA为络合剂,在600℃烧结均可制备出单相LSMO纳米颗粒;样品颗粒主要呈类球型,其中以柠檬酸为络合剂制得的颗粒形貌最佳;这些样品的平均颗粒尺寸分别为24 nm(柠檬酸)、28 nm(酒石酸)、36 nm(醋酸)、38 nm(草酸)、50 nm(EDTA)。以甲基红乙醇溶液为目标降解物,采用可见光源钨灯为辐照光源,研究了LSMO纳米颗粒的光催化性能。结果表明,甲基红的吸附及光催化降解率与反应液中H_2O含量紧密相关,以柠檬酸为络合剂制得的颗粒光催化活性相对较高。LSMO的光催化机理,主要为光生空穴的直接氧化。     

聚丙烯酰胺凝胶法合成BiFeO_3纳米颗粒

采用一种新的聚丙烯酰胺凝胶法制备了BiFeO3纳米颗粒.以无机盐溶液为原料,通过加入丙烯酰胺使溶液成胶;在溶液成胶过程中,丙烯酰胺聚合形成高分子网络骨架,为粒子提供生长的空间.实验表明,以EDTA作为络合剂可以获得高纯BiFeO3粉体.同时发现,在前驱体溶液中添加适量的葡萄糖,可有效抑制凝胶体在干燥过程中发生剧烈塌缩,对提高粉体的质量起到重要作用.SEM观察显示,制得的BiFeO3粉体的粒度分布均匀,颗粒近似呈球形,颗粒间无粘连团聚现象.DSC分析表明,样品的反铁磁和铁电相变温度分别为370和830℃.电滞回线和磁滞回线测量结果表明,样品在室温下具有明显的铁电性和弱铁磁性.     

低温软化学法制备花状纳米结构氧化铜

采用一种低温低耗、环境友好的软化学溶液法制备出具有特殊形貌的纳米氧化铜,探索了络合配比、溶液pH值和反应时间对产物结构、形貌和尺寸的影响,通过XRD和SEM测试分析,结果表明,采用柠檬酸三钠为络合剂,在充分络合（铜络比为3：4）的条件下,适当的pH值范围（10～12）内,可获得由粒径约为十几纳米小颗粒组成的花状、球状结构的纳米CuO粉末,根据实验现象和分析结果,对该特殊形貌特征的纳米结构的形成机理给出了推断。     

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。     

络合剂对溶胶凝胶制备纳米铜及其催化性能影响

为研究络合剂对纳米铜粉体的制备及其催化性能的影响,分别以柠檬酸、葡萄糖为络合剂,采用溶胶-凝胶法制备纳米铜.考察了两种络合剂对制备过程以及产物结构的影响,通过催化苯氧化合成苯酚的反应考察制得的纳米铜粉的催化性能.研究表明:葡萄糖为络合剂制得的纳米铜(G-Cu)平均粒径较小(30 nm),比表面积为5.203 m2/g,在催化苯制苯酚反应时,具有较高的苯转化率(50.30%),但对苯酚的选择性较差;而柠檬酸为络合剂制得的纳米铜(C-Cu)平均粒径为55 nm,比表面积19.517 m2/g,催化苯转化率为21.95%,选择性为38.46%.此外,通过对溶胶凝胶法制备机理分析可知,在形成的胶体结构中,柠檬酸和葡萄糖中的羧基和羟基分别与铜离子进行配位.     

TiOCl_2 溶液低温水解合成金红石型氧化钛纳米粉

由ＴｉＯＣｌ２均相溶液采用低温（室温～６０℃）陈化直接制备了纳米氧化钛针形聚集体颗粒．研究了搅拌和陈化温度对产物形貌及尺寸的影响．结果表明,在搅拌的条件下,产物的形貌为准球形;陈化温度（室温～６０℃）对产物形貌无影响．利用透射电镜（ＴＥＭ）和Ｘ射线衍射（ＸＲＤ）对产物进行了表征,结果表明,产物形貌为针形聚集体,晶型为金红石型．     

一维钛纳米材料的SEM和TEM形貌研究

在10mol／L氢氧化钠溶液中，以溶胶状纳米TiO2为钛源，分别于150℃和180℃采用水热法合成了钛纳米晶须和钛纳米线；以金红石型纳米TiO2为原料在150℃水热合成了钛纳米管。用扫描隧道显微镜（SEM）、电子透射电镜（TEM）对产物进行了表征，结果表明钛酸钠纳米晶须扫描形貌为球形颗粒状，透射形貌为直径l～3nm针尖...     

络合沉淀法合成纳米氧化铜粉体及其性能表征

以Ｃu（ＮＯ_３）_２为原料,采用络合沉淀法合成了纳米级CuＯ粉体,并对产品结构性能进行了表征．探讨了氨水,柠檬酸,乙二胺三种不同络合剂对粉体粒径的影响,三种络合剂得到粉体平均粒径在４０～６０nm之间,粉体的粒径随着络和物稳定性的增加而增大．获得了以氨水为络合剂制备纳米氧化铜粉体的最佳工艺条件,以氨水为络合剂所得ＣuＯ粉体平均粒径４０nm,分散性好、收率高．     

快速热解法制备炭包覆纳米金属磁性颗粒(英文)

以简单金属前躯体为原料通过快速热解法制备炭包覆纳米金属磁性颗粒,通过透射电镜、X-射线衍射、热重-示差扫描同步热分析及振动样品磁强计等对产物形貌、结构、成分与磁性能进行表征。结果表明:采用该方法制备的炭包覆纳米金属磁性颗粒形状为近球形颗粒,粒径均一,其中炭包覆镍纳米磁性颗粒的粒径集中在10nm～30nm范围,炭包覆铁纳米磁性颗粒粒径则在50nm～60nm范围;所制炭包覆纳米金属磁性颗粒在室温下具有顺磁性,其磁性能随金属颗粒含量的变化而改变。该方法有望发展成一种工艺简单,可进行连续工业化生产炭包覆纳米金属磁性颗粒的方法。     

TiOCl2 溶液低温水解合成金红石型氧化钛纳米粉

由TiOCl2均相溶液采用低温（室温－60℃）陈化直接制备了纳米氧化钛针形聚集体颗粒。研究了搅拌和陈化温度对产物形貌及尺寸的影响。结果表明,在搅拌的条件下,产物的形貌为准球形;陈化温度（室温－60℃）对产物形貌无影响。利用透射电镜（TEM）和X射线衍射（XRD）对产物进行了表征,结果表明,产物形貌为针形聚集体,晶型为金红石型。     

Synthesis of TbMnO3 nanoparticles via a polyacrylamide gel route

We report here the synthesis of TbMnO₃ nanoparticles via an acrylamide gel route. XRD, TG analysis, DSC analysis, and FTIR spectroscopy are combinatively used to investigate the thermal decomposition process of precursor xerogels and the formation of TbMnO₃ phase. It is demonstrated that high-phase-purity TbMnO₃ nanoparticles can be prepared by using different chelating agents at a sintering temperature of 800 °C. SEM observation and XRD analysis reveal that the particle size and morphology of the products have a dependence on the chelating agent. The particles prepared using citric acid as the chelating agent appear to be regularly spherical in shape and highly uniform in size with a diameter of ～67 nm, while the sample prepared by using the chelating agent EDTA mainly consists of sphere-, ellipsoid-, and rod-like particles and exhibits a relatively broad particle size distribution with an average particle size centered around 115 nm. The use of a combination of citric acid and EDTA generally results in sphere- and ellipsoid-like particles with an average particle size between those of the samples prepared separately by using the two chelating agents.     

Fabrication and photocatalytic activity of YMn2O5 nanoparticles

In this work, a polyacrylamide gel route is introduced to synthesize YMn₂O₅ nanoparticles. It is demonstrated that high-quality YMn₂O₅ nanoparticles with a uniform size and spherical shape can be prepared using different chelating agents. However, the average particle size of the products is found to have a dependence on the choice of the chelating agent. The sample prepared using citric acid as the chelating agent has an average particle size of ~ 45 nm, while the sample prepared by using the chelating agent EDTA has a particle size centered around 70 nm. The optical energy bandgap of the citric acid- and EDTA-resulted samples is obtained, from optical absorption measurements, to be 1.21 and 1.17 eV, respectively. The photocatalytic experiments reveal that the as-prepared YMn₂O₅ nanoparticles exhibit an interesting photocatalytic activity for oxidative decomposition of methyl red under ultraviolet and visible-light irradiation.     

单分散纳米聚苯乙烯微球的制备及在多孔炭材料中的应用

在超声波辅助下通过微乳液聚合法制备出纳米PS微球,利用重力沉降法制备出聚苯乙烯胶晶阵列,以该阵列为大孔模板制备出大孔一介孔分级炭材料,利用激光粒度仪、场发射扫描电镜、红外和N2物理吸附及解吸附技术对产品的形貌、微观结构及性能进行表征与研究,结果表明,采用超声波辅助微乳液聚合可实现粒径在50nm-500nm范围内聚苯乙烯纳米球的可控制备,增大KPS和PVP用量,PS粒径均会变小,St／SDSN要有适合的比例才能保证PS粒径小且单分散均一。     

Pt／C催化剂的制备及其对甲醇电催化氧化的研究

首次报道了以乙二胺四乙酸（EDTA）作为螯合剂,采用硼氢化钠还原氯铂酸制备Pt／C（Pt的质量分数为20％）纳米催化剂,TEM分析表明,通过改变反应的pH值可以获得分散度与粒径不同的Pt粒子,当pH=12．5时,Pt的分散度最高,平均粒径最小（3．2nm）。催化剂的退火处理研究表明,经270℃氮气氛围内退火后,其电催化活性有了显著提高。使用循环伏安法在甲醇的溶液中电催化氧化研究结果表明,在pH=12．5时制备的催化剂对甲醇的电催化氧化活性最高。     

Liquid-phase synthesis of cobalt oxide nanoparticles

Various liquid-phase syntheses of CoO and Co3O4 nanoparticles have been studied. The experiments focus on two synthesis routes: the coprecipitation and the sol-gel methods combined with thermal decomposition. The effect of synthesis route, the type of precursors (cobalt nitrate/chloride) and precipitation agent (carbonate, hydroxide, oxalic acid, and ammonia), the chemical compositions, pH, application of surfactants (PDMS, Triton X-100, NaDS, NaDBS, TTAB, ethyl acetate, citric acid), and the heat treatments on the properties of particles were investigated. The particle size and distribution have been determined by dynamic light scattering (DLS). The phases and the morphology of products have been analysed by XRD and SEM. The coprecipitation technique is less able to shape the particles than sol-gel technique. PDMS can be applied efficiently as surfactant in preparation methods. The finest particles (around 85 nm) with narrow polydispersity (70-100 nm) and spherical shape could be achieved by using sol-gel technique in medium of 1-propanol and ethyl acetate.     

室温条件下纳米银的温和制备和形貌调控

目的 探究室温条件下不同还原剂以及其他实验助剂在化学还原纳米银过程中对其颗粒粒径、尺寸分布和形貌的影响。方法 以抗坏血酸为还原剂,聚乙烯吡咯烷酮（PVP）为分散剂,柠檬酸钠为保护剂和第2还原剂,选择葡萄糖和硼氢化钠作对照,在室温下通过化学还原的方法来制备纳米银颗粒。通过马尔文激光粒度仪、紫外–可见光谱（UV–vis）、透射电镜（TEM）等对所制备纳米银进行表征。结果 采用抗坏血酸作为还原剂时,通过调控抗坏血酸体积（0.2 mL）,固定柠檬酸钠和PVP体积分别为0.5、0.6 mL,制备出粒径较小（平均粒径为56 nm）且尺寸分布较均一的球形纳米银;采用葡萄糖和硼氢化钠作还原剂时纳米银颗粒尺寸过大（平均粒径分别为216nm和189nm）。结论 采用抗坏血酸作为还原剂,调控柠檬酸钠、PVP等实验参数在最佳范围,更容易制备出球形度好、粒径小的均匀纳米银溶液。     

溶胶-燃烧法制备Ce_(0.8)Gd_(0.2)O_(1.9)及其性能

采用溶胶-燃烧法合成了Gd掺杂CeO2的Ce0.8Gd0.2O1.9(GDC)电解质粉末.研究了热处理温度对其相组成、颗粒大小、晶胞参数的影响.并对GDC烧结体的性能进行了研究.结果表明,溶胶一燃烧法可以成功制备出具有良好的烧结性的GDC电解质粉末,1500℃下得到的GDC烧结体的相对密度可以达到95%.电性能测试表明烧结体在中温范围内具有较高的氧离子电导率.     

Agglomeration behavior of chromia nanoparticles prepared by amorphous complex method using chelating effect of citric acid

Chromia (Cr₂O₃, chromic oxide, Eskolaite) nanoparticles were prepared by amorphous complex method using citric acid as a chelating agent. As a precursor for chromic oxide particle, dried gel with a three-dimensional network consisted of the molar ratio of [citrates]/[chromium ions]=2:1 was prepared. Finally, chromic oxide nanoparticles were formed by calcination of precursor gel at 700 °C for 2 h. Obtained chromic oxide particles were characterized by thermogravimetric and differential thermal analysis, X-ray diffraction, field emission scanning electron microscopy, and Brunauer–Emmett–Teller surface area measurement. It turned out that chromic oxide nanoparticles showed highly agglomerated structure consisted of weakly attached primary particles with each other by van der Waals and capillary adhesive forces. The size distribution of the individual particles was about 20–50 nm. Estimated average particle size from BET surface area was 29.21 nm. The reason for the formation of highly agglomerated structure was discussed.     

Improvement of morphology and luminescence of CaS:Eu<Superscript>2+</Superscript> red-emitting phosphor particles via carbon-containing additive strategy

CaS:Eu²⁺ red-emitting phosphors particles, were prepared by the precipitation method, followed by sintering in the atmosphere over the mixture of sulfur powder, Na₂CO₃, and carbon-containing compounds such as tartaric acid, citric avid, glucose, and cane sugar. The structure, morphology and photoluminescence performance of the as-prepared samples were investigated by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and photoluminescence spectrum (PL), respectively. The influences of carbon-containing additives on its crystallization behavior, morphology, and enhancement in luminescence of CaS:Eu²⁺ particles were studied. CaS:Eu²⁺ particles without additive show inhomogeneous, rough and aggregation with the size of 75–125 nm, but the spherical particles with mean size of about 110 nm were obtained by adding carbon-containing compounds. Compared with phosphor without additive, the addition of carbon-containing materials induced a remarkable increase of PL, in the order of cane sugar, glucose, citric acid, and tartaric acid. This enhancement is duo to the improvement of crystallinity, particle morphology and size distribution of the samples by adding carbon-containing additive.     

Synthesis of ZnO nanopowder via an aqueous acetate-citrate gelation method

The synthesis of nanoparticulate ZnO via an aqueous carboxylate gelation route is presented. Starting from a solution of zinc acetate with citric acid as a complexing agent, a solid glassy gel is obtained after drying that is converted into a fine powder by calcination. It is found that a very homogeneous precursor is indispensable when preparing very fine particles with a narrow size distribution. Cryo-transmission electron microscopy (Cryo-TEM) investigation is used as a feedback tool to prevent early precipitation during gelation. Study of the thermal decomposition of the gel shows that ZnO is formed before the final decomposition step takes place. After removing the organic backbone, very small oxide particles are found. The influence of the thermal treatment parameters on the particle size is investigated and a particle growth process is found. By a proper adjustment of the final calcination temperature in dry air, the mean particle size can be controlled between ∼11 and 175 nm. It was also seen that even in inert atmosphere, ZnO is formed and that particle morphology is greatly influenced by the calcination atmosphere.