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     

Eu3+掺杂纳米TiO2光催化降解亚甲基蓝的研究

采用溶胶-凝胶法制备了Eu3+掺杂的纳米TiO2粉体。以亚甲基蓝溶液为目标降解物研究了掺杂纳米TiO2粉体的光催化性能,并讨论了掺杂TiO2粉体的加入量、亚甲基蓝溶液的初始浓度、pH值以及稀土元素掺杂量和烧成温度等对样品光催化性能的影响。结果表明:在样品加入量为0.15 g/50 mL,亚甲基蓝溶液的初始浓度为10 mg/L,pH=7时样品的光催化性能最佳。稀土元素的最佳掺杂量(摩尔比)为n(Eu3+)∶n(TiO2)=0.5%,样品的热处理温度在500～550℃时,样品表现出较好的光催化活性。掺杂TiO2粉体对亚甲基蓝有良好的降解效果,反应4 h降解率达到88.16%,优于同等条件下制备的纯TiO2粉体。     

LaFeO3的制备及光催化降解酸性品红

采用溶胶-凝胶法制备了钙钛矿型氧化物LaFeO3,并以其为光催化剂对酸性品红溶液进行了降解.考察了制备过程中络合剂、溶胶脱水温度、焙烧温度对LaFeO3样品催化性能的影响,并对不同焙烧温度下制备出的LaFeO3样品进行了XRD表征.结果表明:在500~700℃下焙烧制得的LaFeO3样品物相均为钙钛矿型,随着焙烧温度的升高,LaFeO3晶粒尺寸增加;用柠檬酸作络合剂,在脱水温度为60℃,焙烧温度为600℃下制得的LaFeO3对20mg/L酸性品红溶液的降解率可达到87.56%.     

Co3O4/Ag/PI复合薄膜的制备及光催化性能研究

以聚酰亚胺薄膜为基体,硝酸银、硝酸钴为银源和钴源,通过离子交换法制备Co_3O_4/Ag/PI复合薄膜,并对样品的结构和形貌进行了表征,通过亚甲基蓝的降解率评价复合薄膜的光催化活性.研究结果表明,通过煅烧实现了将Ag+还原成单质Ag、Co2+氧化成Co_3O_4,并均匀分散在PI表面;与Co_3O_4/PI相比,Co_3O_4/Ag/PI的光催化活性明显提高.在制备Co_3O_4/Ag/PI复合薄膜过程中,Ag+最佳含量为60%(物质的量分数),最佳煅烧温度为270℃,亚甲基蓝120 min的降解率达到94%.复合薄膜循环利用5次后,降解率仍然保持在94%左右,表现出很好的稳定性.     

负载纳米TiO2、Ag复合微胶囊光催化性能的研究

以纳米Ag粒子掺杂光催化剂TiO2,采用原位聚合法成功制备负载纳米TiO2/Ag的复合微胶囊;利用扫描电子显微镜、紫外-可见吸收光谱等测试手段对其形貌和光谱性质进行了表征,探讨不同纳米TiO2、Ag加入量的微胶囊在不同光催化时间下对亚甲基蓝光催化效果的影响.结果表明:纳米Ag(1.94%)掺杂TiO(22.78%)的复合微胶囊对亚甲基蓝具有最大脱色率为10.82%,单独添加纳米TiO2和单独添加纳米Ag粒子的微胶囊样品与常规微胶囊比较没有显著差异.     

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_...     

钙钛矿型CaFeO3的制备及其光催化性能研究

以硝酸铁、硝酸钙和柠檬酸为主要原料,采用溶胶-凝胶自蔓延法制备CaFeO3.应用FI-IR、XRD、UV-Vis-DRS、SEM、EDS等技术对CaFeO3进行分析,在紫外光照射下选用酸性橙7(Acid Orange7,AO7)模拟染料废光,考察CaFeO3的催化降解性能.所制备的CaFeO3为钙钛矿型,具有网状结构,...     

Sol-gel法制备介孔WO3-TiO2复合材料及其光催化性能

以非离子表面活性剂P123为结构导向剂,采用溶胶-凝胶法,通过调整P123与(W+Ti)的摩尔比例,经500℃煅烧制备出一系列不同介孔特性的WO3-TiO2复合光催化材料。利用X射线衍射图谱(XRD)、扫描电子显微镜(SEM)、紫外-可见吸收光谱(UV-Vis)、比表面积分析仪(BET)对复合材料的形貌、孔结构及光谱性质进行表征。研究了介孔WO3-TiO2复合材料对罗丹明B的吸附/光催化降解能力。结果表明,以P123为模板剂所制备的介孔WO3-TiO2复合材料表现出较好的吸附/光催化性能,可见光照射下,0.5g的P123、(W+Ti)摩尔比为0.6%的复合材料经500℃煅烧,对200mL罗丹明B(10mmol/L)的吸附降解率140min后达到97.7%。     

WO3-TiO2光催化降解亚甲基蓝的研究

采用半导体WO3复合的改性方法,以钛酸丁酯为主要原料,在室温下,采用溶胶一凝胶法制备W03-TiO2复合光催化剂．WO3-TiO2光催化剂经350W氙灯照射后,用分光光度计测量光催化降解反应后亚甲基蓝溶液的吸光度,考察其光催化活性;考察钨掺杂量、煅烧温度、冰乙酸用量等对光催化活性的影响．结果表明：在WO3摩尔分数1．5％,煅烧温度500℃,冰乙酸用量3mL时,能够有效提高TiO2光催化剂光催化活性．     

累托石/TiO2复合材料的制备及其光催化性能

以钛酸四丁酯为钛源,用溶胶-凝胶法制备了改性累托石/TiO2光催化剂,运用X射线衍射和扫描电镜对其进行了表征.结果表明,累托石结构中负载了纳米TiO2.以300 W紫外灯为光源,以亚甲基蓝为目标降解物,得到制备交联钠化累托石/TiO2复合材料的最佳条件是盐酸浓度为0.2 mol/L,TiO2与累托石添加比例为5 mmol/g,复合材料的煅烧温度为500 ℃.研究了累托石/TiO2光催化剂的光催化性能,当用紫外灯光照20 min,反应温度为30 ℃,溶液pH为6时,亚甲基蓝的去除率达到90%以上.     

自蔓延高温合成La0.67Sr0.33MnO3-δ粉体的研究

采用自蔓延高温合成(SHS)技术合成了La0．67Sr0．33MnO3-δ粉体。研究了KMnO4含量、压坯密度对燃烧反应及退火温度对粉体性能的影响，并用XRD、SEM对粉体的性能进行了表征，结果表明：KMnO4用量为0．3时，反应完全且晶粒大小均匀；反应的原料混合物压坯密实度的降低可使燃烧温度有所增大；最佳退火温度为1100℃。     

退火温度对La0．7Sr0.3MnO3薄膜取向的影响

在LaAlO3(100)单晶上,通过化学溶液法(CSD)制备了有取向性的La0.7Sr0.3MnO3薄膜,对不同退火温度下薄膜的取向性进行了研究.结果表明:随着温度的升高,薄膜的取向性变好.     

Preparation and Monte Carlo Simulation of La0.67Ca0.33MnO3/Cr2O3 Composites

The （ 1 - x ） La0.67Ca0.33MnO3 （ LCMO ） ＋ x Cr2O3 composites were synthesized by a new liquid phase method. The XRD and SEM meusurements reveal that few Cr2O3 were soluble in the LCMO structure and the lattice constant of LCMO almost did not change, while most Cr2O3 were distributed at the grain boundaries or on surfaces of the LCMO grains. In resistivity versus temperature meusurements, a metal-insalator transition was observed when x 〈 0.20. The resistivity increases and the metal-insalator transition temperature deereases with the increasing content of Cr2O3 . A random resistor network （RRN） model was used to simulate the transport property of the mixture samples. The simulation results agree with the experimental observations. The results show that the method is reasonable for understanding the electronic transport of the composites of the manganite.     

La0.7Ca0.3MnO3多晶材料制备及其电磁特性

以化学溶液分解法制备La0.7Ca0.3MnO3粉体,常压烧结制备多晶块体样品。对La0.7Ca0.3MnO3样品的磁矩、磁致电阻效应（CMR）和电脉冲诱导电阻转变效应（EPIR）进行了研究。磁矩零场冷和场冷试验结果发现,居里温度以下,零场冷和场冷条件下磁矩具有较大差别。这说明材料中缺少真正的长程磁有序。La0.7Ca0.3MnO3多晶具有磁致电阻效应,在9 T磁场作用下,磁致电阻变化大约为70%。在80 V,20 ns电脉冲作用下,材料具有电脉冲诱导电阻转变效应。从理论上对磁致电阻效应与电脉冲诱导电阻转变效应的机理进行了分析。     

多晶La0.49Sr0.51(Mn1-xNbx)O3的磁电阻研究

采用四探针法测量多晶La0.49Sr0.51(Mn1-xNbx)O3(x=0,0.05,0.15和0.25)在磁场下的电阻率温度曲线.实验结果显示:①在0.45T磁场下,对于x=0和x=0.25的样品,几乎观察不到磁电阻(Magnetoresistance,MR)效应,而对于x=0.05和x=0.15的样品,磁电阻效应较明显.这种差异可能与样品中铁磁相是否占主导作用有关;②比较x=0.05和x=0.15这两种样品的MR机制,前者可能与载流子在弱连接晶界上的自旋相关散射有关,且其主要是非本征的;而后者主要是本征的.     

Chemical Synthesis and Magnetic Properties of Nanocrystalline (La_(0.67-X)Gd_X)Sr_(0.33)MnO_3 Using Amorphous Molecular Alloy as Precursors

A new route to synthesize nanosized crystalline of(La 0.67–X Gd X )Sr 0.33 MnO 3 (X=0.05,0.10, 0.15,0.20)perovskite-type complex oxides at calcination temperature of 600-1000°C using the amorphous molecular alloy as precursors was reported.The precursor could be completely decomposed into complex oxide at temperature below 500°C according to the TGA and DTA results.XRD demonstrates that the decomposed species is composed of perovskite-type structure at calcination temperature of 600°C for 2 h.The particle size that depends on the calcination temperature of the precursor is in a range of 30-120 nm as determined by transmission electron microscopy(TEM).This method is effective and can be easily quantitatively controlled to synthesize nanosized perovskite-type complex oxides.The magnetic properties of(La 0.67–X Gd X )Sr 0.33 MnO 3 nanocrystalline were preliminary studied.     

Chemieal Synthesis and Magnetie Properties of Nanocrystalline （La0.67-XGdx）Sr0.33MnO3 Using Amorphous Molecular Alloy as Precursors

A new route to synthesize nanosized crystalline of （La0.67-xGdx）Sr0.33MnO3 （X=0.05, 0.10, 0.15, 0.20） perovskite-type complex oxides at calcination temperature of 600-1000℃ using the amorphous molecular alloy as precursors was reported. The precursor could be completely decomposed into complex oxide at temperature below 500℃ according to the TGA and DTA results. XRD demonstrates that the decomposed species is composed of perovskite-type structure at calcination temperature of 600℃ for 2 h. The particle size that depends on the calcination temperature of the precursor is in a range of 30-120 nm as determined by transmission electron microscopy （TEM）. This method is effective and can be easily quantitatively controlled to synthesize nanosized perovskite-type complex oxides. The magnetic properties of （La0.67 xGdx）Sr0.33MnO3 nanocrystalline were preliminary studied.     

Transport properties and microstructure of La0.7Sr0.3MnO3 nanocrystalline thin films grown by polymer-assisted chemical solution deposition

Perovskite-based materials can be widely used in the aerospace and transportation field. Perovskite manganese oxides La_0.7Sr_0.3MnO₃ (LSMO) thin films were grown on LaAlO₃ (100) and Si (100) single crystal substrates by the polymer-assisted chemical solution deposition (PACSD) method. Electronic transport behavior, microstructure, and magnetoresistance (MR) of LSMO thin films on different substrates were investigated. The resistance of LSMO films fabricated on LaAlO₃ substrates is smaller than that on the Si substrates. The magnetic field reduces resistance of LSMO films both on Si and LAO in the wide temperature region, when the insulator-metal transition temperature shifts to higher temperature. The low-field magnetoresistance of LSMO films on Si in low temperature range at 1 T is larger than that of LSMO films on LAO. However, the MR of LSMO film on LAO films at room-temperature is about 5.17 %. The thin films are smooth and dense with uniform nanocrystal size grain. These results demonstrate that PACSD is an effective technique for producing high quality LSMO films, which is significant to improve the magnetic properties and the application of automotive sensor.

     

亚锰酸盐La0.7-xYxCa0.3MnO3的电磁特性和磁电阻效应

研究了用固相反应法制备亚锰酸盐多晶样品La0.7-xYxCa0.3MnO3,并研究了Y的不同掺杂(x=0.1,0.2)对样品的晶体结构、电磁特性和磁电阻效应的影响.实验结果表明,随着温度的降低,x=0.1样品的R-T曲线没有出现峰值,而x=0.2样品出现了峰值,显示了复杂的输运特性.两种样品的磁电阻Rm都随着温度的降低而升高,但都没有出现峰值.x=0.2的样品在较宽的温区内,磁电阻效应都很显著,而且Y掺杂由x=0.1提高至x=0.2,磁电阻效应增强.     

钙钛矿型La0.8Sr0.2MnO3催化剂对氯苯催化燃烧的性能研究

采用共沉淀法制备了钙钛矿型La0.8Sr0.2MnO3催化剂,用XRD,SEM,BET对催化剂进行了表征,考察了催化剂对氯苯的催化燃烧性能.结果表明:La0.8Sr0.2MnO3催化剂呈现钙钛矿晶型,催化剂具有较好的分散性,颗粒尺寸约为60 nm,对氯苯有较好的催化燃烧性能.在氯苯浓度为800~1 600 mg/m3,空速(GHSV)为1 000~4 000 h-1的情况下,反应温度高于350℃时,氯苯几乎能完全去除.稳定性实验结果表明:该催化剂在氯苯浓度为800 mg/m3,空速(GHSV)为1 000 h-1,反应温度为410℃的条件下,经历了100 h连续催化燃烧后,没有出现明显失活,说明La0.8Sr0.2MnO3催化剂对含氯有机物具有较强的抗毒性.