NiFe2O4磁性纳米材料的溶剂热法一步合成

以Fe(NO_3)_3·9H_2O和Ni(NO_3)_2·6H_2O为原料,在未添加任何碱性沉淀剂和高温晶化处理的条件下,通过对实验条件(包括溶剂、溶剂热温度和时间)的优化,利用溶剂热法一步制备了具有良好结晶性和超顺磁性的NiFe_2O_4磁性纳米材料。结果表明:用H_2O和EtOH-H_2O做溶剂都不利于NiFe_2O_4的生成;用EtOH做溶剂,为了获得纯度较高的NiFe_2O_4磁性纳米材料,要保证适当的溶剂热温度和时间;所得材料的磁性能与材料中磁性组分NiFe_2O_4的含量和其结晶程度有关。该制备方法最突出的优点是简单、快速、成本低、从源头消除了污染,且所得的材料磁性能优良。     

磁性TiO2/CoFe2O4纳米复合光催化材料的制备

以磁性CoFe2O4为核,采用改进的溶胶-凝胶法,制备了磁性TiO2/CoFe2O4纳米复合光催化材料.利用VSM(振动样品磁强计)技术对其磁性能进行了研究,结果表明:由该法所得的TiO2/CoFe2O4纳米复合光催化材料的饱和磁化强度虽稍弱于纯CoFe2O4纳米材料,但其矫顽力则优于CoFe2O4.TEM、XRD、UV-Vis等的结果表明,该纳米复合材料中的TiO2为锐钛矿结构;与TiO2相比,纳米复合材料对光的吸收拓展到了整个紫外-可见区,且吸收强度大大增强.对染料废水光催化降解的模拟研究表明,该复合材料在紫外光下,6 h可以使亚甲基蓝染料溶液的脱色率达95%,且重复使用3次时染料溶液的脱色率仍能保持在90%,明显优于纯TiO2.     

大学化学综合实验:Fe/Fe3O4磁性材料的合成、结构性质与磁性能的测定*

推荐一个大学化学综合实验: Fe/Fe3O4磁性材料的合成、结构性质与磁性能的测定,该实验涉及材料的合成、结构表征和磁性能的测定。通过该实验可以使学生掌握一些大型仪器的基本原理和基本操作,掌握材料合成的方法、材料结构及形貌的表征手段以及磁滞曲线的测定方法。使学生在掌握材料研究的基础理论和基本实验技能的同时,培养学生独力实验能力和创新意识,尤其是培养他们综合运用知识的能力。进一步缩短教学与科研的距离。     

纳米BaFe12O19纤维的电纺制备及磁性研究

以PVP的乙酸溶液为助纺剂,采用静电纺丝技术制得了纳米BaFe12O19纤维,利用XRD和EDS对样品的物相和成分进行了分析,利用SEM和TEM对样品形貌和粒径进行了表征,并利用振动样品磁强计(VSM)对样品进行了磁性能研究.结果表明,BaFe12O19/PVP复合纤维经过800℃煅烧后,制得了纯净的BaFe12O19纳米纤维,纤维平均直径为150 nm,呈现出多晶结构,矫顽力为4 164.9 G,与粉体相比,矫顽力有较大提升,有望扩展BaFe12O19在高密度垂直记录材料、微纳米电子材料和微波材料等领域的应用.     

新型固体氧化物燃料电池阴极材料Ca2-xSrxFe2O5的电化学性能研究

采用固相法合成了固体氧化物燃料电池(SOFC)阴极材料2-xSrxFe2O5(x=0.00,0.05,0.10,0.15,0.20),利用XRD和SEM对其结构和微观形貌进行了表征.结果表明该阴极材料与固体电解质Sm0.8Ce0.2O1.9(SDC)在1000℃烧结时不发生化学反应,且烧结4 h后,二者之间可形成良好的接触界面.利用交流阻抗谱技术对阴极材料的电化学性能进行研究,结果显示,阴极上的反应过程主要为电荷的迁移反应,其中Ca1.95Sr0.05Fe2O5电极在空气中700℃下具有最小的极化电阻为0.95Ω·cm2.当测试温度为700℃时,阴极电流密度为74mA·cm-2时,阴极过电位为100mV.     

介孔SiO2/Fe3O4中空磁性微球的漆酶固定化

以介孔SiO2/Fe3O4磁性中空微球作为载体,采用物理吸附法对漆酶进行固定化,考察了时间、温度和pH值对漆酶固定化效果的影响,并对固定漆酶的活性及稳定性进行了研究.结果表明,介孔SiO2/Fe3O4磁性中空微球吸附漆酶分子后,介孔材料的比表面积与孔体积均减小.在3 h时复合微球对漆酶的吸附达到平衡,复合微球中介孔SiO2对漆酶的有效固定量为689 mg/g,大大高于纯介孔材料MCM-41的漆酶固定量(319 mg/g).在pH=3～6的条件下,复合微球中固定漆酶仍保持70%以上的相对酶活.当温度不高于60℃时,固定漆酶的相对酶活仍保持65%以上.固定漆酶的pH稳定性和热稳定性都明显优于游离漆酶,固定漆酶的米氏常数为1.05 mmol/L,与游离漆酶相比,固定漆酶与底物的亲和力有所降低.当2,4-二氯苯酚的浓度为10 mg/L时,固定漆酶对其去除率在6 h时达到81.6%,表现出很好的催化活性.     

正癸酸修饰磁性纳米Fe3O4对溶菌酶的吸附研究

以沉淀法制备了正癸酸修饰磁性纳米Fe3O4,采用XRD、TEM和FT-IR对修饰前后的磁性纳米粒子的形态、结构进行了表征。将修饰后的磁性纳米粒子用于对溶菌酶蛋白进行吸附分离,研究了溶液的pH、温度、时间、溶菌酶初始浓度、离子强度等因素对吸附过程的影响。结果表明:pH=10.7,吸附温度为25℃,吸附时间为2.0 h,溶菌酶初始浓度为0.30 mg·mL-1,最大吸附容量为35.0 mg·g-1。修饰后的磁性纳米粒子用于从鸡蛋清中提取溶菌酶,纯化倍数为30.9,酶活力收得率为73.0%。     

核-壳结构磁性金属有机骨架材料Fe3O4@UiO-66-NH2的合成、表征及催化性能

UiO-66-NH_2是以Zr4+为金属,以2-氨基对苯二甲酸为配体制备得到的金属有机骨架材料,它是目前报道中具有较高热稳定性和化学稳定性的材料之一。本文以Fe_3O_4为核,以UiO-66-NH_2为壳,采用层层自组装方法制备了核-壳结构的磁性金属有机骨架材料Fe_3O_4@UiO-66-NH_2。利用X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)和氮气吸附等对其进行了表征,并考察了该磁性材料在克脑文盖尔(Knoevenagel)缩合反应中的催化性能。结果表明,该磁性材料Fe_3O_4@UiO-66-NH_2为核-壳结构,壳层厚度约为100 nm,氨基含量为1.70 mmol·g-1。该磁性复合材料具有Fe_3O_4和UiO-66-NH_2的双重功能,既可以磁性分离,又具有UiO-66-NH_2的孔结构和催化性能。由于壳层材料中Lewis酸性位(Zr4+)和碱性基团(-NH_2)的协同催化能力及其壳层的纳米尺寸效应,该磁性材料在Knoevenagel缩合反应中表现出和UiO-66-NH_2纳米粒子相当的催化活性。而且,通过磁性分离实现催化剂的多次循环使用后,其结构没有明显变化。     

Zn0.4Ni0.6Cr0.5LaxFe1.5－xO4铁氧体纳米粉晶的制备及磁性

用柠檬酸盐前驱物-溶胶凝胶法制备了Zn_0.4Ni_0.6Cr_0.5La_xFe_1.5－xO₄ (x＝0～0.10)纳米粉晶. 用DSC-TG分析了前驱物转变为粉晶的热分解过程, 通过粉末X射线衍射仪(XRD)、透射电子显微镜(TEM)和振动样品磁强计(VSM)等表征了产物的结构、形貌和磁性能. 结果表明, 不同温度和不同的La掺杂量对样品的晶粒尺寸、晶胞参数和形貌均产生了明显的影响, 且通过改变La含量能起到调控样品磁性能的作用.     

Cu/MoO3-TiO2/SiO2上光催化CO2和C3H8合成异丁烯醛的研究

采用表面改性法和等体积浸渍法制备了金属修饰的负载型复合半导体材料Cu/MoO3-TiO2/SiO2, 用X射线衍射、 比表面积测定、 红外光谱、 拉曼光谱和紫外-可见漫反射等技术对固体材料的结构、 吸光性能和化学吸附性能进行了表征, 研究了该材料对CO2和丙烷合成异丁烯醛的光促表面催化规律. 结果表明, 半导体活性组分MoO3和TiO2在所制备的催化剂Cu/MoO3-TiO2/SiO2表面形成化学键, 并存在多种活性吸附位; 金属Cu的修饰拓展了固体材料对光源的响应范围, 提高了反应体系的吸光能力; 固体材料对CO2和丙烷的有效吸附使其在较低温度下就能促进异丁烯醛的紫外光化学合成, 反应选择性达到85％左右. 根据实验结果对光促CO2和丙烷表面催化合成异丁烯醛的机理进行了讨论.     

Sol-gel synthesis of K3InF6 and structural characterization of K2InC10O10H6F9, K3InC12O14H4F18 and K3InC12O12F18

K₃InF₆ is synthesized by a sol-gel route starting from indium and potassium acetates dissolved in isopropanol in the stoichiometry 1:3, with trifluoroacetic acid as fluorinating agent. The crystal structures of the organic precursors were solved by X-ray diffraction methods on single crystals. Three organic compounds were isolated and identified: K₂InC₁₀O₁₀H₆F₉, K₃InC₁₂O₁₄H₄F₁₈ and K₃InC₁₂O₁₂F₁₈. The first one, deficient in potassium in comparison with the initial stoichiometry, is unstable. In its crystal structure, acetate as well as trifluoroacetate anions are coordinated to the indium atom. The two other precursors are obtained, respectively, by quick and slow evaporation of the solution. They correspond to the final organic compounds, which give K₃InF₆ by decomposition at high temperature. The crystal structure of K₃InC₁₂O₁₄H₄F₁₈ is characterized by complex anions [In(CF₃COO)₄(OH_x)₂]^(5−2x)− and isolated [CF₃COOH_2−x]^(x−1)− molecules with x=2 or 1, surrounded by K⁺ cations. The crystal structure of K₃InC₁₂O₁₂F₁₈ is only constituted by complex anions [In(CF₃COO)₆]³⁻ and K⁺ cations. For all these compounds, potassium cations ensure only the electroneutrality of the structure. IR spectra of K₂InC₁₀O₁₀H₆F₉ and K₃InC₁₂O₁₂F₁₈ were also performed at room temperature on pulverized crystals.     

Li2O-TiO2-SiO2-P2O5和Li2O-TiO2-Al2O3-P2O5体系锂离子固体电解质的制备及性能研究

一些具有NASICON型网格结构的固体电解质具有高的电导率和好的稳定性,NASICON的意思是Na Super Ionic Conductor[1]。当NaZr2(PO4)3中P5 被Si4 部分取代时便可以得到具有NASICON结构的Na1 xZr2SixP3-xO12体系,其具有高的钠离子电导率。然而有相同结构的Li1 xZr2SixP3-xO12体系的离子电导率却很低,这是因为Li 半径太小,而NASICON三维网格结构的离子通道太大,两者不匹配而使电导率下降[2]。但当LiZr2(PO4)3中Zr4 被离子半径小些的Ti4 取代,所得LiTi2(PO4)3的通道就与Li 半径相匹配,适合于锂离子的迁移,从而使其电导率…     

Non-centrosymmetric Ba3Ti3O6(BO3)2

The compound previously reported as Ba₂Ti₂B₂O₉ has been reformulated as Ba₃Ti₃B₂O₁₂, or Ba₃Ti₃O₆(BO₃)₂, a new barium titanium oxoborate. Small single crystals have been recovered from a melt with a composition of BaTiO₃:BaTiB₂O₆ (molar ratio) cooled between 1100°C and 850°C. The crystal structure has been determined by X-ray diffraction: hexagonal system, non-centrosymmetric space group, a=8.7377(11) Å, c=3.9147(8) Å, Z=1, wR(F²)=0.039 for 504 unique reflections. Ba₃Ti₃O₆(BO₃)₂ is isostructural with K₃Ta₃O₆(BO₃)₂. Preliminary measurements of nonlinear optical properties on microcrystalline samples show that the second harmonic generation efficiency of Ba₃Ti₃O₆(BO₃)₂ is equal to 95% of that of LiNbO₃.     

A new 2212-type stair like structure: Bi14Sr21Fe12O61, m=5 member of the generic [Bi2Sr3Fe2O9]m[Bi4Sr6Fe2O16] family

A new oxide, Bi₁₄Sr₂₁Fe₁₂O_61, with a layered structure derived from the 2212 modulated type structure Bi₂Sr₃Fe₂O₉, was isolated. It crystallizes in the I2 space group, with the following parameters: a=16.58(3) Å, b=5.496(1) Å, c=35.27(2) Å and β=90.62°. The single crystal X-ray structure determination, coupled with electron microscopy, shows that this ferrite is the m=5 member of the [Bi₂Sr₃Fe₂O₉]_m[Bi₄Sr₆Fe₂O₁₆] collapsed family. This new collapsed structure can be described as slices of 2212 structure of five bismuth polyhedra thick along , shifted with respect to each other and interconnected by means of [Bi₄Sr₆Fe₂O₁₆] slices. The latter are the place of numerous defects like iron or strontium for bismuth substitution; they can be correlated to intergrowth defects with other members of the family.     

Ion-beam irradiation of lanthanum compounds in the systems La2O3-Al2O3 and La2O3-TiO2

Thin crystals of La₂O₃, LaAlO₃, La_2/3TiO₃, La₂TiO₅, and La₂Ti₂O₇ have been irradiated in situ using 1 MeV Kr²⁺ ions at the Intermediate Voltage Electron Microscope-Tandem User Facility (IVEM-Tandem), Argonne National Laboratory (ANL). We observed that La₂O₃ remained crystalline to a fluence greater than 3.1×10¹⁶ ions cm⁻² at a temperature of 50 K. The four binary oxide compounds in the two systems were observed through the crystalline-amorphous transition as a function of ion fluence and temperature. Results from the ion irradiations give critical temperatures for amorphisation (T_c) of 647 K for LaAlO₃, 840 K for La₂Ti₂O₇, 865 K for La_2/3TiO₃, and 1027 K for La₂TiO₅. The T_c values observed in this study, together with previous data for Al₂O₃ and TiO₂, are discussed with reference to the melting points for the La₂O₃-Al₂O₃ and La₂O₃-TiO₂ systems and the different local environments within the four crystal structures. Results suggest that there is an observable inverse correlation between T_c and melting temperature (T_m) in the two systems. More complex relationships exist between T_c and crystal structure, with the stoichiometric perovskite LaAlO₃ being the most resistant to amorphisation.     

Synthesis, crystal structure, infrared and Raman spectra of Sr4Cu3(AsO4)2(AsO3OH)4·3H2O and Ba2Cu4(AsO4)2(AsO3OH)3

The two new compounds, Sr₄Cu₃(AsO₄)₂(AsO₃OH)₄·3H₂O (1) and Ba₂Cu₄(AsO₄)₂(AsO₃OH)₃(2), were synthesized under hydrothermal conditions. They represent previously unknown structure types and are the first compounds synthesized in the systems SrO/BaO-CuO-As₂O₅-H₂O. Their crystal structures were determined by single-crystal X-ray diffraction [space group C2/c, a=18.536(4) Å, b=5.179(1) Å, c=24.898(5) Å, β=93.67(3)°, V=2344.0(8) Å³, Z=4 for 1; space group P4₂/n, a=7.775(1) Å, c=13.698(3) Å, V=828.1(2) Å³, Z=2 for 2]. The crystal structure of 1 is related to a group of compounds formed by Cu²⁺-(XO₄)³⁻ layers (X=P⁵⁺, As⁵⁺) linked by M cations (M=alkali, alkaline earth, Pb²⁺, or Ag⁺) and partly by hydrogen bonds. In 1, worth mentioning is the very short hydrogen bond length, D···A=2.477(3) Å. It is one of the examples of extremely short hydrogen bonds, where the donor and acceptor are crystallographically different. Compound 2 represents a layered structure consisting of Cu₂O₈ centrosymmetric dimers crosslinked by As1φ₄ tetrahedra, where φ is O or OH, which are interconnected by Ba, As2 and hydrogen bonds to form a three-dimensional network. The layers are formed by Cu₂O₈ centrosymmetric dimers of CuO₅ edge-sharing polyhedra, crosslinked by As1O₄ tetrahedra. Vibrational spectra (FTIR and Raman) of both compounds are described. The spectroscopic manifestation of the very short hydrogen bond in 1, and ABC-like spectra in 2 were discussed.     

Raman scattering investigations on lanthanum-doped Bi4Ti3O12-SrBi4Ti4O15 intergrowth ferroelectrics

The ferroelectric ceramics of Bi₄Ti₃O₁₂, SrBi₄Ti₄O₁₅, and lanthanum-doped Bi₄Ti₃O₁₂-SrBi₄Ti₄O₁₅ were synthesized, and their Raman spectra were investigated. La-doping resulted in the enlargement of remnant polarization of Bi₄Ti₃O₁₂-SrBi₄Ti₄O₁₅. The structure of the Bi₂O₂ layers and TiO₆ octahedra of the intergrowth was found to be different from those of Bi₄Ti₃O₁₂ and SrBi₄Ti₄O₁₅. La³⁺ ions exhibit pronounced selectivity for the occupation of A site as La content is lower than 0.50, and tend to be incorporated into Bi₂O₂ layers when the La content is higher than 0.50. Lanthanum substitution brings about the structural phase transition in Bi₄Ti₃O₁₂-SrBi₄Ti₄O₁₅. The variation of ferroelectric property may be attributed to combined contribution from the decreasing of the oxygen vacancies, the relaxation of the lattice distortion, the destroying of the insulation and the space charge compensation effects of the Bi₂O₂ slabs.     

g-C_3N_4/CaTi_2O_5复合材料制备及其光催化性能

利用类石墨氮化碳(g-C_3N_4)和亚稳相钙钛氧化物(CaTi_2O_5)固相法制备C_3N_4/CaTi_2O_5复合材料。利用X射线衍射(XRD)、金相显微镜、扫描电子显微镜(SEM)及附带能谱分析仪(EDS)和N2吸附-脱附对样品的显微结构和比表面积进行检测分析,并用紫外-可见吸收光度计(UV-Vis)测试了样品的光吸收性能,研究C_3N_4与CaTi_2O_5物质的量之比(nC_3N_4/nCaTi_2O_5)对C_3N_4/CaTi_2O_5复合样品的物相结构和微观形貌的影响,同时考察C_3N_4/CaTi_2O_5复合样品在可见光照射下光催化降解罗丹明染料效果。实验结果表明:相比纯C_3N_4和CaTi_2O_5样品,C_3N_4/CaTi_2O_5复合样品在可见光下具有较高的光催化性能,随着nC_3N_4/nCaTi_2O_5增加,样品的光催化降解率随之增加而后降低,当nC_3N_4/nCaTi_2O_5=1∶1时,样品的光催化降解率达到最大值99.5%,并且循环重复利用5次后,样品的光催化剂降解率仍几乎保持不变。复合样品光催化性能提高主要归因于复合能级结构有效地抑制了电子和空穴复合所致。     

Magnetic diphase nanostructure of ZnFe2O4/γ-Fe2O3

Magnetic diphase nanostructures of ZnFe₂O₄/γ-Fe₂O₃ were synthesized by a solvothermal method. The formation reactions were optimized by tuning the initial molar ratios of Fe/Zn. All samples were characterized by X-ray diffraction, thermogravimetric analysis, infrared spectroscopy, and Raman spectra. It is found that when the initial molar ratio of Fe/Zn is larger than 2, a diphase magnetic nanostructure of ZnFe₂O₄/γ-Fe₂O₃ was formed, in which the presence of ZnFe₂O₄ enhanced the thermal stability of γ-Fe₂O₃. Further increasing the initial molar ratio of Fe/Zn larger than 6 destabilized the diphase nanostructure and yielded traces of secondary phase α-Fe₂O₃. The grain surfaces of diphase nanostructure exhibited a spin-glass-like structure. At room temperature, all diphase nanostructures are superparamagnetic with saturation magnetization being increased with γ-Fe₂O₃ content.     

g-C3N4/CaTi2O5复合材料制备及其光催化性能

利用类石墨氮化碳（g-C₃N₄）和亚稳相钙钛氧化物（CaTi₂O₅）固相法制备C₃N₄/CaTi₂O₅复合材料。利用X射线衍射（XRD）、金相显微镜、扫描电子显微镜（SEM）及附带能谱分析仪（EDS）和N₂吸附-脱附对样品的显微结构和比表面积进行检测分析,并用紫外-可见吸收光度计（UV-Vis）测试了样品的光吸收性能,研究C₃N₄与CaTi₂O₅物质的量之比（n_C3N4/nCaTi₂O₅）对C₃N₄/CaTi₂O₅复合样品的物相结构和微观形貌的影响,同时考察C₃N₄/CaTi₂O₅复合样品在可见光照射下光催化降解罗丹明染料效果。实验结果表明：相比纯C₃N₄和CaTi₂O₅样品,C₃N₄/CaTi₂O₅复合样品在可见光下具有较高的光催化性能,随着n_C3N4/nCaTi₂O₅增加,样品的光催化降解率随之增加而后降低,当n_C3N4/nCaTi₂O₅=1：1时,样品的光催化降解率达到最大值99.5%,并且循环重复利用5次后,样品的光催化剂降解率仍几乎保持不变。复合样品光催化性能提高主要归因于复合能级结构有效地抑制了电子和空穴复合所致。