纳米微孔杂多化合物Na[Fe2(O2H3)Mo2O8](Ⅰ)和(NH4)[Fe(MoO4)2](Ⅱ)的结构特征

通过采用水热合成法得到了二种具有纳米筛孔的氧簇化合物Na[Fe2(O2H3)Mo2O8](Ⅰ)和(NH4)[Fe(Mo O4)2](Ⅱ).晶体(Ⅰ)属于单斜晶系,空间群为C2/m,晶胞参数为:a=9.5450(17),b=6.4381(9),c=0.76405(12)nm;β=116.128(4),Z=2,R1=0.0219,Rw=0.0756.晶体(Ⅱ)属于正交晶系,空间群为Pnma,晶胞参数为:a=1.4782(3),b=0.56774(11),c=0.87653(18)nm;Z=4,R1=0.0212,Rw=0.0513.     

[H(4,4''''-bpy)]2[K2Mo8O26]的水热合成和结构研究

采用水热法合成了[H(4,4'-bpy)]2[K2Mo8O26],X-ray单晶结构解析表明该化合物属三斜晶系,空间群P-1,晶胞参数a=0.78029(8)nm,b=0.98715(8)nm,c=1.32438(6)nm,α=99.383(3),β=102.0600(19),γ=108.090(2),β-[Mo8O26]单元通过部分端氧原子与K原子相连成层状,4,4'-联吡啶中质子化的N原子与非质子化的N原子通过氢键联成链状,链与链之间通过π-π堆垛成层状结构.     

复合材料Co2（OH）4-x(C10H17O2)x·zH2O的差热分析与磁特性

将有机手性配体3,7-二甲基-6-辛烯酸(C10H18O2)嫁接到无机层状羟基醋酸钴中,合成出新型的有机-无机杂化材料,并对这些杂化材料通过元素和热重分析,研究了有机配体在无机层间的交换过程,并在此基础上讨论了合成出的这些杂化材料的磁性特性。     

金属间化合物Tb(Fe1-xMnx)11.3Nb0.7的结构和磁性

研究了Mn部分替代TbFe11.3Nb0.7中的Fe对化合物结构和磁性的影响.利用真空电弧熔炼和真空热处理制备了Tb(Fe1-xMnx)11.3Nb0 7(x=0.05,0.10,0.15,0.20)化合物样品.粉末样品的X射线衍射和热磁曲线测量表明用Mn部分取代TbFe11.3Nb0.7中的Fe仍保持ThMn12型结构,且具有较好的单相性.晶格常数a和单胞体积V随Mn含量的增加而增大,但晶格常数c的增大比较平缓.所有这些化合物中都存在自发磁化现象,且其居里温度均≥300K.随着Mn含量的增加,化合物在4.4 K温度下的饱和磁化强度逐渐减小,平均每个Mn原子替代引起的饱和磁矩的降低约为3.4μB,过渡金属次晶格磁矩随Mn含量的增加也单调减小.     

空心结构(C12H8N2)3·H3PMo12O40/WO3的制备及光催化研究

制备了杂多化合物(C12H8N2)3.H3PMo12O40和空心结构复合催化剂(C12H8N2)3.H3PMo12O40/WO3,采用等离子体原子发射光谱(ICP-AES)、元素分析(EA)、热重-差热分析(TG-DTA)、X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)、扫描电镜(SEM)、能量色散X射线谱(EDS)、紫外-可见漫反射吸收光谱(UV-vis DRS)进行了表征。在高压汞灯照射下,研究了杂多化合物(C12H8N2)3.H3PMo12O40、空心WO3微球和空心复合催化剂(C12-H8N2)3.H3PMo12O40/WO3对罗丹明B水溶液的光催化降解活性,结果表明,在复合催化剂中,杂多化合物(C12-H8N2)3.H3PMo12O40和WO3具有协同作用,光催化活性比单独的杂多化合物和WO3都高。     

Fe3O4负载Ti3C2Tx对Pb(Ⅱ)的吸附性能研究

Ti₃C₂T_x MXene材料具有二维层状结构及丰富的表面官能团,是一种非常有潜力的重金属离子吸附材料,但其层间距较小,且在水溶液中的稳定性较差。本工作探索了Ti₃C₂T_x的改性策略,提高其化学稳定性与离子吸附容量,利用一步水热方法制备出不同Fe₃O₄掺杂量的Fe₃O₄-Ti₃C₂T_x(FeMX)复合吸附剂材料。研究结果表明：FeMX吸附剂对Pb(Ⅱ)的理论饱和吸附量可达到210.54 mg/g。研究进一步揭示了FeMX材料对Pb(Ⅱ)离子的吸附机理,Fe₃O₄纳米颗粒均匀分散、插层在Ti₃C₂T_x纳米片层间,有效增加了Ti₃C₂T_x     

共沉淀法制备(Ni,Zn)Fe2O4纳米复合材料及其特性研究

以FeSO₄·7H₂O、NiSO₄·6H₂O和ZnSO₄·7H₂O为原料,通过共沉淀法先制备出晶粒细小的碱式碳酸盐前驱体,在不同的温度下焙烧1 h,制备出(Ni,Zn)Fe₂O₄纳米晶复合材料,利用XRD和TEM等方法对样品进行了分析表征;并考察了其气敏特性和红外吸收性能。结果表明:(Ni,Zn)Fe₂O₄在500℃下开始固相反应并结晶成为纳米晶体,在800℃下晶粒尺寸约为50nm。      

(K0.45Na0.55)0.98Li0.02Nb0.77Ta0.18Sb0.05O3-Co0.85Cu0.15Fe2O4复合陶瓷的磁电性能研究

以压电体(K0.45Na0.55)0.98Li0.02Nb0.77Ta0.18Sb0.05O3和压磁体Co0.85Cu0.15Fe2O4为原料,通过传统的固相反应法制备了(1-x)[(K0.45Na0.55)0.98Li0.02Nb0.77Ta0.18Sb0.05O3]-xCo0.85Cu0.15Fe2O4多铁性复合陶瓷,并使用X射线衍射仪、扫描电子显微镜、压电测试仪、铁电测试仪和磁电耦合测试仪对物相、显微结构、压电、铁电、磁电耦合性能进行了分析。结果表明,复合陶瓷的相结构保持为(K0.45Na0.55)0.98Li0.02Nb0.77Ta0.18Sb0.05O3和Co0.85Cu0.15Fe2O4两种物相,但两者之间发生了轻微的化学反应。随着Co0.85Cu0.15Fe2O4压磁相含量的增加,复合陶瓷的压电系数从56pC/N减小到21pC/N,剩余极化强度略有降低。在压磁相含量为0.2时可获得4.3mV·cm-1·Oe-1的最佳磁电耦合系数。     

Fe2O3 core-NaCo[Fe(CN)6] shell nanoparticles—Synthesis and characterization

A facile precipitation route was developed for the synthesis of cobalt hexacyanoferrate (CoHCF) as a thin shell around cores of nanoparticles of iron(III) oxide, forming nanoparticles of iron(III) oxide@CoHCF (n-Fe₂O₃@NaCo[Fe(CN)₆]). The morphology and structure of the as-prepared n-Fe₂O₃@NaCo[Fe(CN)₆] were characterized by the techniques of electron microscopies, X-ray diffraction measurements, X-ray photoelectron spectroscopy, infrared spectroscopy and thermogravimetry. Carbon composite electrodes of n-Fe₂O₃@NaCo[Fe(CN)₆] were prepared and the electrochemical behavior of the nanoparticles was evaluated using cyclic voltammetry. The redox couples of n-Fe₂O₃@NaCo[Fe(CN)₆] were investigated and the diffusion coefficients of counter cation in the shell of CoHCF were obtained. The effect of size of particles and the structure of CoHCF was also evaluated. n-Fe₂O₃@NaCo[Fe(CN)₆] represented prominent electrocatalytic activity toward the oxidation of some biologically active compounds.     

Preparation and characterization of porous ultrafine Fe2O3 particles

Porous ultrafine Fe₂O₃ particles were prepared by homogeneous precipitation method. Fe³⁺ and urea were chosen as starting materials and anionic surfactant as the template. It is shown that the reaction results in the precipitation of a gelatinous hydrous iron oxide/surfactant mixture, which gives ultrafine Fe₂O₃ particles after drying and calcinations. The products were characterized by XRD, TEM, TG/DTA and BET. Conventional XRD patterns show that the products are mixture of γ-Fe₂O₃ and α-Fe₂O₃ phase after being sintered at 350 °C, and γ-Fe₂O₃ transforms entirely to α-Fe₂O₃ when sintered at 650 °C. The low-angle XRD patterns indicate that the mesostructure can only exist between 350 and 400 °C. TEM results show that the Fe₂O₃ particles have diameters of about 30 nm and lengths ranging from 100 to 120 nm; in each particle, there are several vermiculate-like mesopores with diameter of about 20-25 nm. The BET surface areas in excess of 50 m²/g are obtained after calcinations at 350 °C. The BJH desorption average pore width is around 22 nm, which is in agreement with the TEM results. The results show that anionic surfactant and sintering temperature are important to obtain this special morphology.     

Fe2O3微纳米管阵列的制备及场发射性能研究

首先采用草酸氧化法在Fe基片上生长FeC2O4.2H2O微纳米棒,然后再利用草酸对微纳米棒中部进行选择性刻蚀制备出FeC2O4.2H2O微纳米管,最后在400℃空气中热氧化处理2h获得Fe2O3微纳米管。XRD及ESEM分析测试表明,热氧化后的微纳米管主要成分为Fe2O3,管径约1μm,管壁厚约100nm,顶端有细小纳米尖,直径约20nm。场发射测试结果表明,Fe2O3微纳米管具有低的开启场强(2.34V/μm),大电流密度(1.5mA/cm2),高的场增强因子(10347)以及良好的发光效果。     

Structural characterization, thermal, spectroscopic and magnetic studies of the (C3H12N2)0.75[Mn1.50Fe1.50(AsO4)F6] and (C3H12N2)0.75[Co1.50Fe1.50(AsO4)F6] compounds

The (C₃H₁₂N₂)_0.94[Mn_1.50Fe_1.50^III(AsO₄)F₆] and (C₃H₁₂N₂)_0.75[Co_1.50Fe_1.50^III(AsO₄)F₆] compounds 1 and 2 have been synthesized using mild hydrothermal conditions. These phases are isostructural with (C₃H₁₂N₂)_0.75[Fe_1.5^IIFe_1.5^III(AsO₄)F₆]. The compounds crystallize in the orthorhombic Imam space group. The unit cell parameters calculated by using the patterns matching routine of the FULPROOF program, starting from the cell parameters of the iron(II),(III) phase, are: a = 7.727(1) Å, b = 11.047(1) Å, c = 13.412(1) Å for 1 and a = 7.560(1) Å, b = 11.012(1) Å, c = 13.206(1) Å for 2, being Z = 8 in both compounds. The crystal structure consists of a three-dimensional framework constructed from edge-sharing [M^II(1)₂O₂F₈] (M = Mn, Co) dimeric octahedra linked to [Fe^III(2)O₂F₄] octahedra through the F(1) anions and to the [AsO₄] tetrahedra by the O(1) vertex. This network gives rise two kinds of chains, which are extended in perpendicular directions. Chain 1 is extended along the a-axis and chain 2 runs along the c-axis. These chains are linked by the F(1) and O(1) atoms and establish cavities delimited by eight or six polyhedra along the [1 0 0] and [0 0 1] directions, respectively. The propanediammonium cations are located inside these cavities. The thermal study indicates that the structures collapse with the calcination of the organic dication at 255 and 285 °C for 1 and 2, respectively. The Mössbauer spectra in the paramagnetic state indicate the existence of two crystallographically independent positions for the iron(III) cations and a small proportion of this cation in the positions of the divalent Mn(II) and Co(II) ones. The IR spectrum shows the protonated bands of the H₂N- groups of the propanediamine molecule and the characteristic bands of the [AsO₄]³⁻ arsenate oxoanions. In the diffuse reflectance spectra, it can be observed the bands characteristic of trivalent iron(III) cation and divalent Mn(II) and Co(II) ones in a distorted octahedral symmetry. The calculated Dq and B-Racah parameters for the cobalt(II) phase are 710 and 925 cm⁻¹, respectively. The ESR spectra of compound 1 maintain isotropic with variation in temperature, being g = 1.99. Magnetic measurements for both compounds indicate that the main magnetic interactions are antiferromagnetic in nature. However, at low temperatures small ferromagnetic components are detected, which are probably due to a spin decompensation of the two different metallic cations. The hysteresis loops give values of the remnant magnetization and coercive field of 84.5, 255 emu/mol and 0.01, 0.225 T for phases 1 and 2, respectively.     

Structural and dielectric properties of A(Fe1/2Ta1/2)O3 [A = Ba, Sr, Ca]

The complex perovskite oxide barium iron tantalate (BFT), BaFe_1/2Ta_1/2O₃, strontium iron tantalate (SFT), SrFe_1/2Ta_1/2O₃ and calcium iron tantalate (CFT), CaFe_1/2Ta_1/2O₃ are synthesized by a solid-state reaction technique. Rietveld refinement of the X-ray diffraction data of the samples shows that BFT and SFT crystallize in cubic structure, with lattice parameter a = 4.06 Å for BFT and 3.959 Å for SFT, whereas CFT crystallizes in orthorhombic structure having lattice parameters a = 5.443 Å, b = 5.542 Å and c = 7.757 Å. Fourier transform infrared spectra show two primary phonon modes of the samples at around 450 cm⁻¹ and 620 cm⁻¹. The compounds show significant frequency dispersion in its dielectric properties. The complex impedance plane plots of the samples show that the relaxation (conduction) mechanism in these materials is purely a bulk effect arising from the semiconductive grains. The relaxation mechanism of the samples is modelled by Cole-Cole equation. The frequency dependent conductivity spectra are found to follow the power law.     

Growth and characterization of Fe3O4 films

Iron oxide films were grown on sapphire substrates by pulsed laser deposition at substrate temperatures between 100 and 700 °C. X-ray diffraction, Raman spectroscopy, and vibrational sample magnetometer analysis revealed that structural and magnetic properties of the iron oxide films strongly depend on the substrate temperature during growth. Single phase Fe₃O₄ film was successfully grown on sapphire substrate at a substrate temperature of 500 °C. The saturation magnetic moment of the single phase Fe₃O₄ film is 499 emu/cm³, which is in good agreement with the value reported for bulk magnetite, suggesting the Fe₃O₄ film is of high crystal quality without antiphase boundaries.     

Structural characterization and AC conductivity of bis tetrapropylammonium hexachlorado-dicadmate, [N(C3H7)4]2Cd2Cl6

Synthesis, crystal structure, vibrational study, ¹³C, ¹¹¹Cd CP-MAS-NMR analysis and electrical properties of the compound [N(C₃H₇)₄]₂Cd₂Cl₆, are reported. The latter crystallizes in the triclinic system (space group , Z = 2) with the following unit cell dimensions: a = 9.530(1) Å, b = 11.744(1) Å, c = 17.433(1) Å, α = 79.31(1)°, β = 84.00(1)° and γ = 80.32(1)°. Besides, its structure was solved using 6445 independent reflections down to R = 0.037. The atomic arrangement can be described by alternating organic and inorganic layers parallel to the plan, made up of tetrapropylammonium groups and Cd₂Cl₆ dimers, respectively. In crystal structure, the inorganic layer, built up by Cd₂Cl₆ dimers, is connected to the organic ones through van der Waals interaction in order to build cation-anion-cation cohesion. Impedance spectroscopy study, reported in the sample, reveals that the conduction in the material is due to a hopping process. The temperature and frequency dependence of dielectric constants of the single crystal sample has been investigated to determine some related parameters to the dielectric relaxation.     

Effects of Fe2O3 doping on the microstructure and piezoelectric properties of 0.55Pb(Ni1/3Nb2/3)O3-0.45Pb(Zr0.3Ti0.7)O3 ceramics

0.55Pb(Ni_1/3Nb_2/3)O₃-0.45Pb(Zr_0.3Ti_0.7)O₃(PNN-PZT) ceramics with different concentration of xFe₂O₃ doping (where x = 0.0, 0.8, 1.2, 1.6 mol%) were synthesized by the conventional solid state sintering technique. X-ray diffraction analysis reveals that all specimens are a pure perovskite phase without pyrochlore phase. The density and grain size of Fe-doped ceramics tend to increase slightly with increasing concentration of Fe₂O₃. Comparing with the undoped ceramics, the piezoelectric, ferroelectric and dielectric properties of the Fe-doped PNN-PZT specimens are significantly improved. Properties of the piezoelectric constant as high as d₃₃ ~ 956 pC/N, the electromechanical coupling factor k_p ~ 0.74, and the dielectric constant ε_r ~ 6095 are achieved for the specimen with 1.2 mol% Fe₂O₃ doping sintered at 1200 °C for 2 h.     

Physicochemical characterization of Fe3O4/SiO2/Au multilayer nanostructure

The purpose of this research was to synthesize and characterize gold-coated Fe₃O₄/SiO₂ nanoshells for biomedical applications. Magnetite nanoparticles (NPs) were prepared using co-precipitation method. Smaller particles were synthesized by decreasing the NaOH concentration, which in our case this corresponded to 35 nm using 0.9 M of NaOH at 750 rpm with a specific surface area of 41 m² g⁻¹. For uncoated Fe₃O₄ NPs, the results showed an octahedral geometry with saturation magnetization range of 80–100 emu g⁻¹ and coercivity of 80–120 Oe for particles between 35 and 96 nm, respectively. The magnetic NPs were modified with a thin layer of silica using Stober method. Small gold colloids (1–3 nm) were synthesized using Duff method and covered the amino functionalized particle surface. Magnetic and optical properties of gold nanoshells were assessed using Brunauer–Emmett–Teller (BET), vibrating sample magnetometer (VSM), UV–Vis spectrophotometer, atomic and magnetic force microscope (AFM, MFM), and transmission electron microscope (TEM). Based on the X-ray diffraction (XRD) results, three main peaks of Au (1 1 1), (2 0 0) and (2 2 0) were identified. The formation of each layer of a nanoshell is also demonstrated by Fourier transform infrared (FTIR) results. The Fe₃O₄/SiO₂/Au nanostructures, with 85 nm as particle size, exhibited an absorption peak at ∼550 nm with a magnetization value of 1.3 emu g⁻¹ with a specific surface area of 71 m² g⁻¹.