双功能Fe3O4/Au、Fe3O4/Au@SiO2复合微球的构筑和磁学性质研究

给出一种温和条件下构筑Fe3O4/Au,Fe3O4/Au@SiO2复合纳米结构材料的方法,并研究所得产物的光学、磁学性质。首先,用3-氨丙基三甲氧基硅烷(APS)对平均粒径300 nm的Fe3O4微球进行表面修饰使得其拥有大量的氨基官能团(-NH2),利用这些官能团末端的孤对电子可以共价吸附Au纳米粒子的特性,在一定条件下制备出Fe3O4/Au复合纳米结构材料,不经过任何表面处理利用St?ber方法在室温条件下对其进行SiO2包覆,得到Fe3O4/Au@SiO2复合材料。借助场发射扫描电子显微镜(FESEM)、透射电子显微镜(TEM)对产物的形貌和结构进行表征,并利用紫外-可见(Uv-Vis)分光光度计和超导量子干涉仪(SQUID)对产物的光学和磁学性质进行分析。结果表明,由于所含金浓度太低,Fe3O4/Au复合材料并没有显示金纳米粒子的特征表面等离子体共振吸收峰;Fe3O4/Au,Fe3O4/Au@SiO2复合纳米结构均显示出超顺磁性和高的饱和磁化率。     

TiO2/Fe2O3纳米复合材料的制备及光催化性能

分别以Fe(NO₃)₃·9H₂O和钛酸四丁酯为铁源和钛源,以HF、HAc、NH₄F、NH₃·H₂O、H₂O₂为形貌控制剂,通过沉淀分离法联合溶胶-凝胶法制备了不同形貌的TiO₂/Fe₂O₃纳米复合材料。用X-射线粉末衍射仪(XRD)和场发射扫描电子显微镜(FESEM)对TiO₂/Fe₂O₃样品的结构和形貌进行了分析,并探究了所合成的TiO₂/Fe₂O₃纳米复合材料在紫外光照射条件下对亚甲基蓝(MB)的降解性能。结果表明,当以NH₃·H₂O为形貌控制剂时,制备的NH₃·H₂O-TiO₂/Fe₂     

Au/Al2O3催化剂上环己烷氧化

针对金催化剂制备过程的复杂性和氯离子残留问题,介绍一种负载型金催化剂Au/Al2O3的制备方法和考察该催化剂在环己烷氧化中的催化性能.采用浸渍-氨洗法制备Au/Al2O3催化剂,并应用电感耦合等离子体原子发射光谱(ICP-AES)、X射线衍射(XRD)和透射电子显微镜(TEM)对其进行表征.以氧气氧化环己烷制备环己酮和环己醇为研究对象,考察金质量分数、反应温度、压力、时间等因素对催化活性的影响.结果表明,随着金质量分数增加,金颗粒增大,催化剂的活性降低,在150℃、1.5MPa条件下反应3h,Au实际质量分数为0.58%的Au/Al2O3催化剂上环己烷转化率为8.96%,环己酮、环己醇和环己基过氧化氢三者的总选择性为93.52%.此外,循环实验表明Au/Al2O3催化剂具有一定的稳定性.     

Cu-Cr2O3/Al2O3催化剂上乳酸乙酯加氢制丙二醇研究

在间歇反应器上考察了通过共沉淀法制备得到的一系列不同负载的Cu-Cr2O3/Al2O3催化剂的催化加氢效果.研究结果表明:当n(Cu)∶n(Cr)=2∶1时有最佳的催化剂活性,n(Cu)∶n(Cr)=1∶1时有最佳的1,2-丙二醇选择性.在反应温度为200℃、氢气压力为3MPa、搅拌速率为500r/min和n(Cu)∶n(Cr)=2∶1的Cu-Cr2O3/Al2O3催化剂作用下,反应6h,实现了乳酸乙酯的完全转化,其中1,2-丙二醇的收率达到了95.3%.     

Fe3O4纳米材料的制备及其抗菌性

以氯化亚铁、草酸和水合肼为原料,采用水热法制备出Fe3O4纳米材料。用X射线衍射仪(XRD)和扫描电子显微镜(SEM)对产品的结构、形貌和尺寸进行了表征。考察了Fe3O4纳米材料的形成条件,并研究了Fe3O4纳米材料的抗菌性。实验结果表明:Fe3O4纳米材料对甲基营养型芽孢杆菌有一定的抑制作用。     

Fe3O4/SnS2的制备及其催化性能研究

为提高Fe₃O₄的类芬顿效果,基于光助类芬顿催化氧化技术,在共沉淀法制备Fe₃O₄的基础上采用醇热法制备能高效降解亚甲基蓝的Fe₃O₄/SnS₂催化剂。建立了以Fe₃O₄/SnS₂为催化剂的光助类芬顿催化氧化体系,分析不同制备及降解条下Fe₃O₄/SnS₂的类芬顿活性,并通过X射线衍射(XRD)、扫描电子显微镜(SEM)等对Fe₃O₄/SnS₂材料进行表征。结果表明：当Fe₃O₄和SnS₂物质的量比为1∶1时,Fe₃O₄/SnS₂的催化效果最好;亚甲基蓝溶液pH为3.0、Fe₃O_...     

基于双金属MOFs 制备Co3O4/In2O3 复合物及其气敏性能的研究

以硝酸铟(In(NO₃)₃·xH₂O)、对苯二甲酸(H₂BDC)、六水合硝酸钴(Co(NO₃)· 6H₂O) 为原料, 首先采用一锅油浴法合成了含有Co²⁺ 的铟基金属有机框架材料(MOFs) Co²⁺/CPP-3(In) 材料, 然后在450 ℃ 下焙烧制备Co₃O₄/In₂O₃ 复合物气敏材料, 将Co₃O₄/In₂O₃ 复合物的粉体制作成传感器, 并对其气敏性能进行研究。利用扫描电子显微镜和X 射线衍射仪(XRD) 对双金属MOFs Co²⁺/CPP-3(In) 材料和Co₃O₄/In₂O₃ 复合物进行表征, 采用静态配气法测试其气敏性能。结果表明, Co₃O₄/In₂O₃(n_Co : n_In = 0.4 : 1) 样品的形貌保留了其MOFs 前驱体的棒状结构, 棱柱形框架更为突出, 表面呈凹陷状, 棒体中间粗两边细, 六角截面和棒体均布满了孔洞。结合EDX 和XRD 表征结果, Co²⁺/CPP-3(In) MOFs 前驱体完全转化成Co₃O₄/In₂O₃ 复合物; Co₃O₄/In₂O₃(n_Co : n_In = 0.4 : 1) 复合物在 70 ℃ 下对5×10^-6 H₂S 的气敏性能最优, 响应值达到153, 是同条件下纯备In₂O₃对H₂S 响应值的5 倍, 并且有较好的重复性、选择性和稳定性。     

ZnO-Sb2O3-P2O5系统玻璃的制备与性能

用熔体冷却方法制备了xSb2O3-(70-x)P2O5-30ZnO(x=0~40mol)和xSb2O3-(65-x)ZnO-35P2O5(x=0~40mol)系统无铅易熔玻璃,研究了ZnO-Sb2O3-P2O系统玻璃的形成区。采用热膨胀仪和红外光谱仪等对ZnO-Sb2O3-P2O5系统玻璃的结构及性能进行了研究和分析。结果表明,在ZnOSb2O3-P2O5系统玻璃中,Sb2O3参与网络结构。随着Sb2O3含量的增加,玻璃的软化点降低,密度和化学稳定性增加。在Sb2O3摩尔分数为35%左右时,系统玻璃的结构和性能比较优异。     

BaO-TiO2-Nd2O3-La2O3系陶瓷结构与介电性质研究

在BaO-TiO2-Nd2O3(BTN)系材料中以La2O3部分取代Nd2O3后构成BaO-TiO2-Nd2O3-La2O3(BTNL)系的结构和介电性能。实验结果证实,随着La2O3和Nd2O3摩尔比的增加,介电常数的温度系数((下降,用XRD分析证明是因为BaLa2Ti4O12和La2Ti2O7相的增加所致。在BTNL系中加入适量的添加剂可获得中温下烧结的具有超低损耗的微波陶瓷材料,可用于研制微波独石电容器。     

以Mn3O4为锰源合成高性能LiMn2O4正极材料

以Mn3O4为锰源,采用固相反应法,在较低的温度(650℃)制得尖晶石LiMn2O4正极材料。采用X射线衍射(XRD)、扫描电镜(SEM)、循环伏安和恒流充放电等技术对其相组成、微结构和电化学性能进行表征。结果表明该正极材料结晶良好,一次粒径约为150 nm。它的电化学性能,尤其是循环性能,明显优越于在较高温度合成的LiMn2O4。在电流密度为74 mA?g-1时,测得比容量为128 mAh?g-1,在1 480 mA?g-1时,比容量为105 mAh?g-1;在室温、148 mA?g-1充放电200次循环后,容量保持率为93%。     

三氧化二铝是导致建筑物火灾的严重隐患

建筑物供电线路中的铜线与铝线连接处常常生成一种灰白物质－－三氧化二铝,极易引发建筑物火灾。着重介绍和分析这种灰白物质的成分、生成原因、危害以及防止其生成的主要措施。     

Luminescent properties of BaO-La2O3-B2O3 glasses with dopant

The luminescent properties of glasses synthesized in air atmosphere by conventional high temperature process were stud{ed. The emissions spectra of Eu^2 and Eu^3 were observed in BaO-La2O3-B2O3-Eu2O3 glasses.The results show that the broad emission peaks at 430 nm correspond to 5d→4f emission transition of Eu^2 , the sharp emission peaks at 592, 616, 650 and 250 nm correspond to 5^D0→1Fj(j=1--4) emission transition of Eu^3 ,respectively, which indicates that the BaO-La2O3a-B2O3-Eu2O3 glass can convert ultraviolet and green omponents of sunlight into blue and red light so as to increase the intensity of blue and red light, respectively. The luminescent in--tensity of Eu^2 increases with increasing the molar ratio of Tb^3 in BaO-La2O3-B2O3-Eu2O3a-Tb4O3 glasses, whereas the luminescent intensity of Eua^3 decreases. So the luminescent intensity of Eu(Ⅲ,Ⅱ) is influenced by Tb^3 .These phenomena can be explained by electron transfer mechanism; Eu^3 (4f6) Tb^3 (4f^8)→Eu^2 (4f′) Tb^4 (4f′). Taking advantage of the luminescent properties of BaO-La2O3-B2O3-Eu2O3 glasses, light-conversion glass for agriculture can be produced.     

Structure of Bi2O3-ZnO-B2O3 system low-melting sealing glass

Bi_2O_3-ZnO-B_2O_3 system glass is a kind of lead-free low melting sealing glasses. The structure of Bi_2O_3-ZnO-B_2O_3 system low-melting sealing glass was investigated by DSC, FT-IR, XRD and SEM. The results show that with the increase of B_2O_3 content, the transition temperature Tg and softening temperature T_f of Bi_2O_3-ZnO-B_2O_3 system low-melting sealing glasses increase, which leads to the liquid phase precipitation temperature increasing and promotes the structure stability in the glass. With increasing the heat treatment temperature, a large number of liquid phases appear in samples and the sinter efficiency of the samples increases. The FT-IR spectra of the glasses show the presence of some bands that are assigned to vibrations of Bi-O bond from [BO_3] pyramidal and [BiO_6] octahedral units and B-O from [BO_3] and [BO_4] units. With the decrease of B_2O_3 content, the crystallization tendency of the glass increases. In glass samples B_1 and B_2, crystallization starts at 460 ℃ and 540 ℃, respectively. Both of them precipitate Bi-(24)B_2O_(39) phases.     

Modification of nano-TiO2 by Al2O3 in-situ coating

A novel technology of in-situ coating Al₂O₃ on the surface of H₄TiO₄ was developed to prevent the aggregation of nano-TiO₂ powders and improve the dispersibility and thermal stability in the way of forming a uniform coating layer. The heterogeneous nucleation was conducted to prepare the precursor of nano-TiO₂ and then Al₂O₃ was coated on the surface of precursor. The effects of Al₂O₃ in-situ coating on the properties of nano-TiO₂ were investigated. The results show that H₄TiO₄ can be dispersed well under alkaline condition (pH 8.5) and the heterogeneous nucleation can be controlled easily. The optimized uniform coating layer is obtained by adding 5% (mass fraction) and 10% of Al₂O₃ and the aggregation of nano-TiO₂ powders is effectively inhibited and the dispersibility is obviously improved. The crystal sizes of TiO₂ powders are 12.3, 11.4 and 8.7 nm after coating 0,5% and 10% of Al₂O₃ respectively. Al₂O₃ on the surface of particulates in amorphous phase could increase the thermal stability of nano-particles after calcined at 550 °C. Foundation item: Project(04GK2007) supported by Hunan Industrial Key Project of Science and Technology     

Microstructure and microwave dielectric properties of CaO-B2O3-SiO2 glass ceramics with various B2O3 contents

The effects of B2O3 addition on both the sintering behavior and microwave dielectric properties of CaO-B2O3-SiO2 (CBS) glass ceramics were investigated by Fourier transform infrared spectroscopy (FTIR),X-ray diffractometry (XRD) and scanning electron microscopy (SEM).The results show that the increasing amount of B2O3 causes the increase of the contents of [BO3],[BO4] and [SiO4],which deduces the increase of CaB2O4 and α-SiO2 and the decrease of CaSiO3 correspondingly.No new phase is observed throughout the...     

Pressureless reactive sintering mechanism of nanocrystalline Bi2O3-Y2O3 solid electrolyte

The nanocrystalline Bi2O3-Y2O3 solid electrolyte material was synthesized by pressureless reactive sintering process with Bi2O3 and Y2O3 nano mixed powder as raw materials, which was prepared by a chemical coprecipitation process. The study on the behavior of nano δ-Bi2O3 formation and its grain growth showed that the solid solution reaction of Y2O3 and β-Bi2O3 to form δ-Bi2O3occurs mainly in the initial stage of sintering process, and nano δ-Bi2O3 crystal grains grow approximately following the rule of paracurve ((D-D0)2=K.t) during sintering process. After sintered at 600℃ for 2 h, the samples could reach above 96% in relative density and have dense microstructure with few remaining pores, the δ-Bi2O3 grains are less than 100 nm in size.     

SnO2及SnO2／Fe2O3复合微米材料的合成及表征

本文首先以SnCl2·2H2O为主要原料,无水乙醇为溶剂,利用溶剂热法于180℃反应24h得到了SnO2微球;再以所制备的SnO2微球为前驱体,FeCl3·6H2O为主要原料,通过水热法得到SnO2／Fe2O3复合材料．利用X射线粉末衍射仪（XRD）和扫描电子显微镜（SEM）对所得产物进行了表征．结果表明：所得的SnO2为四方锡石型,形貌为微球,平均直径约为2．0μm;复合后得到的SnO2／Fe2O3微球平均直径约为2．5μm．其中,Fe2O3为六方赤铁矿型,在复合物的表面以小颗粒的形式存在,尺寸约为200nm．另外,也对SnO3与SnO2／Fe2O3微球的形成过程进行了讨论．     

一种基于 MXene 的Fe2O3/Nb2O5/Nb4C3Tx 高灵敏丙酮传感器

MXene 具有较大比表面积和优异的导电性, 当与金属氧化物半导体结合时可以抑制片层团聚, 还可以大大提高载流子转移速率, 提高气敏性能。通过简单的水热和煅烧两步法成功合成了Fe₂O₃/Nb₂O₅/Nb₄C₃T_x 三元复合材料。通过表征, Fe₂O₃ 微米球分布在 MXene 纳米片层之间。气敏测试结果表明, 与原始Fe₂O₃相 比, Fe₂O₃/Nb₂O₅/Nb₄C₃T_x 传感器对丙酮的响应能力有明显的提高。传感器灵敏度高, 选择性较好, 对环境中 浓度为 5 ×10^?6 的丙酮响应高 (R_a /R_g = 7.81, 30% RH), 响应和恢复速度快, 具有出色的重复性和长期稳定性。Fe₂O₃/Nb₂O₅/Nb₄C₃T_x 传感器具有良好的气敏性能, 主要因为三元复合材料提供了较大比表面积和丰富的氧空位, 增强了活性位点, 使得气体易于在传感器表面扩散, 为开发丙酮敏感复合材料提供了参考。     

Electrodeposition of Ni-Co-Fe2O3 composite coatings

Ni-Co-Fe₂O₃ composite coatings were electrodeposited using cetyltrimethylammonium bromide (CTAB)-modified Watt’s nickel bath with Fe₂O₃ particles dispersed in it. The effects of the plating parameters on the chemical composition, structural and morphological characteristics of the electrodeposited Ni-Co-Fe₂O₃ composite coatings were investigated by energy dispersive X-ray (EDS) spectroscopy, X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The results reveal that Fe₂O₃ particles can be codeposited in the Ni-Co matrix. The codeposition of Fe₂O₃ particles with Ni-Co is favoured at high Fe₂O₃ particle concentration and medium stirring, and the deposition of Co is favoured at high concentration of CTAB. Moreover, the study of the textural perfection of the deposits reveals that the presence of particles leads to the worsening of the quality of the observed 〈220〉 preferred orientation. Composites with high concentration of embedded particles exhibit a preferred crystal orientation of 〈111〉. The more the embedded Fe₂O₃ particles in the metallic matrix, the smaller the sizes of the crystallite for the composite deposits.     

氧化铝增强的PdSe2/Si异质结光电探测器

为了降低暗电流,通过原子层沉积(ALD)生长了一层氧化铝(Al₂O₃)隧穿层,制备了PdSe₂/Al₂O₃/Si异质结光电探测器.通过优化Al₂O₃层的厚度,使得该探测器实现了高速和宽光谱响应.研究结果表明,在波长为808 nm的光照射和-2 V偏压下,所制备的光电探测器与未生长Al₂O₃的器件相比,暗电流降低了约3个数量级,器件的光响应度达到了约为0.31 A/W,对应的比探测率约为2.5×10¹² Jones,器件在零偏压下表现出明显的自驱动效应.经过循环测试1 200次后,器件保持良好的光响应.器件响应的上升时间和下降时间分别为7.1和15.6μs.结果表明,在二维层状半导体材料与Si之间引入Al₂O₃隧穿层,可以有效地降低器件的暗电流,有利于高性能的Si基光电探测器的制备.