铁酸镁超微粒子的制备及结构特征

采用两种方法制得了尖晶石结构纯相MgFe2O4样品．Moessbauer分析发现,一种样品表现出了完全的超顺磁性,另一种表现出了部分超顺磁性．这揭示出了样品具有很小的粒子尺度．首次在实验上发现了MgFe2O4IR-V2谱带的劈裂现象,报导了拉曼光谱,通过ESR分析,进一步揭示了两样品的结构特征,并讨论了性质之间的相关性。     

MgFe2O4@(TF-LDHs)磁性纳米复合体的制备与表征

以镁铁尖晶石(MgFe2O4)颗粒为磁性基质, 采用共沉淀法制备了替加氟(TF)插层层状双金属氢氧化物(LDHs)包覆MgFe2O4的核-壳结构磁性纳米复合体[MgFe2O4@(TF-LDHs)], 并对其化学组成、 晶体结构和磁性等进行了表征, 探讨了TF在LDHs层间的存在状态, 考察了TF的释放行为. 实验结果表明, MgFe2O4@(TF-LDHs)纳米复合体具有顺磁性, 其比饱和磁化强度随磁性基质含量的增大而增强; TF分子在LDHs层间以长轴略倾斜于LDHs层板的方式呈双层排布; MgFe2O4@(TF-LDHs)纳米复合体具有明显的药物缓释效果, 其释放动力学过程符合准二级动力学方程, 释放机理为Fick扩散; 增大磁性基质含量或施加外加磁场均可减缓其药物释放过程.     

正电性磁性氧化铁胶粒负载钯催化的Suzuki偶联反应

发展了一种超顺磁性Fe3O4纳米粒子负载Pd0的简易方法. 利用Fe3O4溶胶带正电荷的特性, 将负离子 通过静电作用吸附在Fe3O4胶体粒子表面( /Fe3O4), 以抗坏血酸(Vc)进一步还原即得到载有金属Pd团簇的Fe3O4胶体粒子(Pd0/Fe3O4). 该磁性载体负载的Pd催化剂对Suzuki反应表现出良好的催化活性, 且在反应后, 可方便地通过永久磁铁将催化剂从反应体系中分离出来, 进行循环使用. 试验表明, 该催化剂在循环使用五次后反应活性无明显下降. 进一步试验发现, 这种磁性纳米粒子负载的金属钯对一系列卤代芳烃的Suzuki偶联反应均表现出较优的催化活性.     

化学发光法快速筛选纳米微粒模拟酶

本文提出了一种基于化学发光法快速筛选纳米微粒模拟酶的新方法,以H2O2-鲁米诺化学发光反应为模型体系,对CoFe2O4、CuFe2O4、γ-Fe2O3、MnFe2O4、NiFe2O4前驱体和MgFe2O4前驱体等6种铁氧体纳米微粒的过氧化物模拟酶活性进行快速筛选,并与辣根过氧化物酶（HRP）进行比较．结果表明：（1）与HRP类似,6种铁氧体纳米微粒均能够催化H2O2氧化鲁米诺产生增强化学发光,其催化活性依赖于pH、温度以及底物（H2O2）浓度;6种铁氧体纳米微粒均能够催化H2O2氧化TMB的显色反应,表明其具有过氧化物模拟酶特性;（2）以H2O2为底物的表观米氏常数（Km）从小到大依次为CoFe2O4〈y-Fe2O3〈NiFe2O4前驱体〈CuFe2O4〈MnFe2O4〈MgFe2O4前驱体;（3）铁氧体纳米微粒模拟酶比HRP具有更佳的pH及温度耐受能力．本法简单、快速,可用于大规模纳米微粒模拟酶的快速筛选．     

SO2-4/ZrO2/Fe3O4/Al2O3磁性固体超强酸的制备与表征

用化学共沉淀法制备了一系列SO2-4/ZrO2/Fe3O4/Al2O3磁性固体超强酸, 利用XRD、IR、TG-DSC、VSM、TEM及HRTEM等手段对样品结构进行了表征. 结果表明, 引入一定量的Fe3O4和Al2O3有利于四方晶相ZrO2(t)结构的稳定；Fe3O4超细粒子的引入, 使固体超强酸具备了超顺磁性；HRTEM 结果显示ZrO2晶体生长趋向于ZrO2(t)的[101]方向,其(101)晶面间距为d(101)=0.29 nm, 与XRD 衍射结果一致. Hammett 指示剂测得样品SZA-20-200-800酸强度(H0<-13.8)最强, 酸性大于浓硫酸(H0=-11.9).     

Polyol合成法制备生物医药用超小粒径Fe3O4磁性纳米晶体

采用一罐polyol合成法还原Fe（Ⅲ）乙酰丙酮化合物制备了粒径可调、单分散、直径5nm以下的磁性Fe3O4纳米晶体．其晶粒表面为所用聚合物表面活性剂PVP所包覆．运用透射电镜／高分辨透射电镜、X射线衍射、振动样品磁强计和超导量子干涉仪对其结构和性能进行了表征．结果表明所制得的Fe3O4磁性纳米晶体在室温下显示出优良的超顺磁性,且结晶度高、分散性好、化学性质稳定同时表面易修饰．磁滞回线的模型分析说明该Fe3O4纳米晶粒是磁性单畴．该法制得的超顺磁Fe3O4纳米晶粒在生物和医学领域具有重要的应用价值．     

深冷状态下纳米镝铁氧体磁粒子磁性能的研究

采用湿化学法制备出稀土Dy3+掺杂的纳米Fe3O4磁粒子,用月桂酸进行了表面修饰,研究了磁粒子在室温和深冷(200.2～56.5 K)状态下的磁性能.经X射线衍射分析发现,适量的Dy3+掺杂不会改变纳米Fe3O4磁粒子的晶型结构.透射电镜(TEM)照片表明,制备出的纳米磁粒子成球性好,且大部分磁粒子的粒径在14 nm左右.通过磁性测量仪、振动样品磁强计(VSM)对磁性能进行了表征.磁化曲线表明掺杂引起磁性能发生变化,磁粒子室温下无剩磁和矫顽力,具有超顺磁性;深冷状态下出现剩磁和矫顽力,且随温度的降低,剩磁和矫顽力增大,不具有超顺磁性,饱和磁化强度略高于室温值.     

多孔超顺磁性纳米磷酸钙(PSMN-CaP)的制备研究

近来,磁性纳米磷酸钙,因良好的生物相容性和组织键合能力,备受研究者的关注。采用磁性纳米粒子Fe_3O_4做核,CTAB做结构导向剂制备出具有多孔结构的超顺磁性纳米磷酸钙复合物(PSMN-CaP)。通过XRD、FI-IR、N2吸附/脱附、TEM和磁性能对样品进行了分析表征。结果表明:制备出的样品PSMN-CaP具有超顺磁性多孔结构,粒径约为80 nm,饱和磁化强度为9.4 emu·g~(-1)。     

CuCrO2和CrCr2O4间相互作用对体系结构和催化性能的影响

 以柠檬酸络合法制备了CuCrO2和CuCr2O4两相共生的Cu－Cr－O催化剂体系．由于两相共生而相互作用，两相组成的样品中，样品颗粒较小，比表面积增大，催化CO－O2反应的活性提高．当样品中n（Cu）／n（Cr）＝0．7时，两相含量最为接近，显示出最高的催化活性．CO－O2反应过程中，气相中的CO与样品表面的氧原子作用．在两相共生而相互作用的过程中，CuCrO2和CuCr2O4的体相结构没有变化．各样品催化活性的不同是由其表面性质的差异引起的．TPR和XPS分析结果表明：两相共生而相互作用，修饰了样品的表面性质，使样品表面含有更多的活性氧，提高了样品的催化活性．     

低温陈化超声波共沉淀制备SO4^2-/ZrO2-La2O3催化剂

低温陈化超声波共沉淀法制得SO4^2-/ZrO2-La2O3前驱体,经H2SO4处理,在不同温度下焙烧得到纳米晶催化剂SO4^2-/ZrO2-La2O3;用Hammett指示剂法测定其酸性．用XRD、BET、TEM、IR和XPS对样品进行表征,其催化活性用醋酸和甘油的酯化反应进行了评价．结果表明经超声波搅拌和低温（-15℃）陈化,650℃焙烧4h得到的固体超强酸表现出较高催化活性．     

MgFe2O4纳米颗粒及其气敏性研究

利用Sol-gel燃烧法合成氧化物MgFe2O4对氯气有很高的灵敏度,并利用XRD对产品的物相进行了分析;用TEM对粉体晶粒和形貌进行检测,将产物粉体制成气敏元件,采用静态配气法在气敏测试仪上进行了灵敏度和响应-恢复曲线的测试,研究证明镁铁复合氧化物对氯气有很好的气敏特性。     

三氧化二砷磁性纳米粒的表征及其在小鼠组织中的药代动力学

通过溶剂转移法制备了三氧化二砷铁氧体磁性纳米粒(As₂O₃-MNPs). 利用扫描电镜/能谱分析、红外光谱(IR)和差示扫描量热法(DSC)等技术对其进行了表征. 选择正常小鼠肝脏作为靶区, 在外加磁场的诱导下, 考察As₂O₃-MNPs在小鼠体内的组织药代动力学特征, 以此反映该磁性纳米粒的磁靶向性效果. 红外光谱分析结果显示, As₂O₃-MNPs中存在磁性材料MgFe₂O₄; DSC分析表明, 制备磁性纳米粒所用材料As₂O₃、乳酸羟基乙酸共聚物(PLGA)和铁氧体之间没有明显的相互作用, 可用于磁性纳米粒的制备; 能谱分析结果显示As₂O₃和磁性材料MgFe₂O₄ 不是吸附于纳米粒的表面, 而是包裹于其中; 磁场组小鼠肝脏组织中药物浓度-时间曲线下面积(AUC_0-∞)、达峰浓度(c_max)和消除半衰期(t_1/2)均明显大于非磁场组(P<0.05), 说明As₂O₃-MNPs在正常小鼠体内有良好的磁靶向性分布. 所制备的三氧化二砷磁性纳米粒稳定性好, 靶向性强, 在肿瘤治疗方面具有良好的应用前景.     

Stoichiometric synthesis of a pure ferrite from a tailored layered double hydroxide (hydrotalcite-like) precursor

Calcination of a layered double hydroxide precursor containing MgII, FeII and FeIII cations with an Mg2+:(FeII + FeIII) ratio of 0.5 affords a pure ferrite spinel, MgFe2O4, which has a higher saturation magnetization than samples of the same material produced by conventional ceramic routes.     

A novel method for the synthesize of nanostructured MgFe2O4 photocatalysts

Journal of Sol-Gel Science and Technology - Nanostructured MgFe2O4 magnetic photocatalysts are facilely synthesized by 60Co γ-ray irradiation assisted polyacrylamide gel route. The influence...     

MgFe2O4@SiO2–SO3H: an efficient,reusable catalyst for the microwave-assisted synthesis of benzoxazinone and benzthioxazinone via multicomponent reaction under solvent free condition

Research on Chemical Intermediates - We report the synthesis of sulfuric acid-functionalized silica-coated magnetic nanoparticles (MgFe2O4@SiO2–SO3H) as a catalyst for the microwave-assisted...     

MgFe2O4纳米粉体的水热合成及其表征(英)

MgFe₂O₄ nanoparticles were hydrothermally synthesized at 150 ℃ using iron nitrate [Fe(NO₃)₃·9H₂O], magnesium nitrate [Mg(NO₃)₂·6H₂O] and sodium hydroxide (NaOH) as starting materials by carefully controlling the reaction conditions. The influences of several factors such as presence or absence of Na⁺, molar ratio of Fe³⁺ / Mg²⁺, concentration of mental ions, temperature and reaction time on resultant products were investigated in the hydrothermal process. The sample was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), and its magnetic properties were measured using vibrating sample magnetometer (VSM).     

Cobalt and magnesium ferrite nanoparticles: preparation using liquid foams as templates and their magnetic characteristics

An easy and convenient method for the synthesis of cobalt and magnesium ferrite nanoparticles is demonstrated using liquid foams as templates. The foam is formed from an aqueous mixture of an anionic surfactant and the desired metal ions, where the metal ions are electrostatically entrapped by the surfactant at the thin borders between the foam bubbles and their junctions. The hydrolysis is carried out using alkali resulting in the formation of desired nanoparticles, with the foam playing the role of a template. However, in the formation of ferrites with the formula MFe(2)O(4), where the metal ion and iron possess oxidation states of +2 and +3, respectively, forming a foam from a 1:2 mixture of the desired ionic solutions would lead to a foam composition at variance with the original solution mixture because of greater electrostatic binding of ions possessing a greater charge with the surfactant. In our procedure, we circumvent this problem by preparing the foam from a 1:2 mixture of M(2+) and Fe(2+) ions and then utilizing the in situ conversion of Fe(2+) to Fe(3+) under basic conditions inside the foam matrix to get the desired composition of the metal ions with the required oxidation states. The fact that we could prepare both CoFe(2)O(4) and MgFe(2)O(4) particles shows the vast scope of this method for making even multicomponent oxides. The magnetic nanoparticles thus obtained exhibit a good crystalline nature and are characterized by superparamagnetic properties. The magnetic features observed for CoFe(2)O(4) and MgFe(2)O(4) nanoparticles are well in accordance with the expected behaviors, with CoFe(2)O(4) particles showing higher blocking temperatures and larger coercivities. These features can easily be explained by the contribution of Co(2+) sites to the magnetocrystalline anisotropy and the absence of the same from the Mg(2+) ions.     

Ordered mesoporous MFe(2)O(4) (M = Co, Cu, Mg, Ni, Zn) thin films with nanocrystalline walls, uniform 16 nm diameter pores and high thermal stability: template-directed synthesis and characterization of redox active trevorite

In this paper, we report on ordered mesoporous NiFe(2)O(4) thin films synthesized via co-assembly of hydrated ferric nitrate and nickel chloride with an amphiphilic diblock copolymer, referred to as KLE. We establish that the NiFe(2)O(4) samples are highly crystalline after calcination at 600 °C, and that the conversion of the amorphous inorganic framework comes at little cost to the ordering of the high quality cubic network of pores averaging 16 nm in diameter. We further show that the synthesis method employed in this work can be readily extended to other ferrites, such as CoFe(2)O(4), CuFe(2)O(4), MgFe(2)O(4), and ZnFe(2)O(4), which could pave the way for innovative device design. While this article focuses on the self-assembly and characterization of these materials using various state-of-the-art techniques, including electron microscopy, grazing incidence small-angle X-ray scattering (GISAXS), time-of-flight secondary ion mass spectrometry (TOF-SIMS), X-ray photoelectron spectroscopy (XPS), as well as UV-vis and Raman spectroscopy, we also examine the electrochemical properties and show the benefits of combining a continuous mesoporosity with nanocrystalline films. KLE-templated NiFe(2)O(4) electrodes exhibit reasonable levels of lithium ion storage at short charging times which stem from facile pseudocapacitance.