Co2-W型六角晶系铁氧体的制备和表征

以金属硝酸盐为原料,柠檬酸为络合剂,乙二醇为分散剂,用柠檬酸溶胶_凝胶法制备了Co2-W型六角晶系铁氧体.采用TG-DTA、XRD、SEM研究了样品物相组成、显微结构和晶化过程.结果表明,煅烧温度低于1200℃时,产物为M晶型的铁氧体;煅烧温度为1250～1300℃时,生成单一的W型铁氧体;温度1350℃时,产物中生成了少量M晶型铁氧体.随着保温时间的延长,W晶型逐渐纯化,保温时问超过5h时,产物中生成了少量M晶型铁氧体.当铁含量为15.1,450℃预处理3h后,在1250～1300℃下煅烧3h,可得到完整的Co2-W型铁氧体.     

Morphology control of barium ferrite thin films

Hexagonal barium ferrite thin films were fabricated by spin coating of precursors obtained by sol-gel methods onto sapphire (00l) faces. Citric acid and ethylenediaminetetraacetic acid (EDTA) were used to tune the morphology of the films. The films show texture with c-axis normal to the film plane as shown by the strong x-ray diffractions from the (001) plane with full width at half maximum of the rocking curves about 0.4°. The [100] direction of the film is parallel to the [110] direction of the sapphire. With the increase of the citric acid, the percentage of the acicular crystallites increased. EDTA can be used to produce films with the best texture where faceted grains were obtained. The maximum coercive force obtained was about 302 kA/m.     

Synthesis and characterization of ferromagnetic cobalt-doped tin dioxide thin films

Co-doped SnO₂ thin films are grown on sapphire (0001) substrates at 600 °C by the technique of dual-beam pulsed laser deposition. The prepared films show preferred orientation in the [100] direction of the rutile structure of SnO₂. Nonequilibrium film growth process results in doping Co into SnO₂ much above the thermal equilibrium limit. A Film with 3% of Co is ferromagnetic at room temperature with a remanent magnetization of ∼ 26% and a coercivity of ∼ 9.0 mT. As Co doping content x increases, the optical band gap absorption edge (E₀) of the Co-doped SnO₂ thin films initially shows a redshift at low x up to x = 0.12 and then increases at the higher x, which are attributed to the sp-d exchange interactions and alloying effects, respectively.     

Synthesis and characterization of boron-oxygen-hydrogen thin films at low temperatures

We have studied the influence of synthesis temperature on chemical composition and mechanical properties of X-ray amorphous boron-oxygen-hydrogen (B-O-H) films. These B-O-H films have been synthesized by RF sputtering of a B-target in an Ar atmosphere. Upon increasing the synthesis temperature from room temperature to 550 °C, the O/B and H/B ratios decrease from 0.73 to 0.15 and 0.28 to 0.07, respectively, as determined by elastic recoil detection analysis. It is reasonable to assume that potential sources of O and H are residual gas and laboratory atmosphere. The elastic modulus, as measured by nanoindentation, increases from 93 to 214 GPa, as the O/B and H/B ratios decreases within the range probed. Hence, we have shown that the effect of impurity incorporation on the elastic properties is extensive and that the magnitude of the incorporation is a strong function of the substrate temperature.     

Synthesis and characterization of NiPcTSTNa(L) thin films

NiPcTSTNa(L) [L = ethylenediamine (EDA); 1,4-diaminobutane (BDA); and 2,6-diamineanthraquinone (AqDA)] thin films were deposited by thermal evaporation. Their surface morphology was studied by AFM and SEM, and their chemical composition determined by EDS. Optical absorption studies of NiPcTSTNa(L) films were performed in the 200?C1150?nm wavelength range. The optical bandgap of thin films was determined from the (??h ??)^1/2 vs h?? plots for indirect allowed transitions. The temperature dependence of electrical conductivity shows a semiconducting behaviour. The amorphous semiconductor films show thermal activation energies of electrical conduction between 3·3 and 3·7?eV.     

ZnO/CdO复合薄膜的制备及其性能研究

通过脉冲激光沉积法首次制备了ZnO/CdO复合薄膜。采用X射线衍射、光致发光和电阻率测量分析了薄膜的结构、光学和电学性能。光致发光谱表明所有ZnO/CdO复合薄膜都具有相同的PL发光峰,保持了未掺杂ZnO的发光特性。同时,复合薄膜的电阻率大大地下降了几个数量级,接近了纯CdO薄膜的电阻率。这可以用Matthiessen公式来解释。与传统掺杂方法相比,制备的ZnO/CdO复合薄膜可同时具有ZnO的发光特性和CdO的电学特性,从而获得单一TCO材料所不具备的性能,满足某些特殊需求。     

Pulsed laser deposition of Mn-Zn ferrite thin films

Mn-Zn ferrite thin films were deposited on sapphire substrates by pulsed laser deposition from sintered Mn_{1 – x}Zn _x Fe₂O₄ ceramic targets. A full stoichiometric transfer from targets to substrates was achieved. Magnetic inplane measurements in two perpendicular directions were carried out and the macromagnetic properties of films were determined. The hysteresis loops obtained are rectangular and the values of the coercive force, the saturation, and the remanent magnetization are comparable to the same parameters of the bulk Mn-Zn ferrite. The films were characterized using a vibrating sample magnetometer (VSM), a scanning electron microscope (SEM) and by X-ray photoelectron spectroscopy (XPS).     

Synthesis and characterization of bulk cobalt-doped ZnO and their thin films

(ZnO)_1?x (Co₃O₄) _x≤0.05 thin-film series were deposited in vacuum Ar–O₂ and N₂ environment using the pulsed-laser deposition (PLD) technique. Bulk pellets were prepared by the solid-state reaction technique by mixing ZnO and Co₃O₄ powder and further utilized for deposition of thin films. XRD patterns of pellets exhibit homogeneous ZnCoO phase formation with no other impurity phases. Single-phase (002) oriented ZnCoO thin films were formed without any cobalt segregation. The cobalt core peaks confirmed the existence of +2 valence state of cobalt in thin-film samples, and the binding energy difference between the cores peaks showed the homogeneous doping of cobalt in ZnO matrix. The magnetic ordering was achieved in thin films samples which were deposited in vacuum and N₂ ambience.     

Synthesis and characterization of vanadium oxide thin films on different substrates

In this study, the V₈O₁₅ derivative of vanadium oxide was produced on plain glass, indium tin oxide and silicon wafer substrate layers by taking advantage of wet chemical synthesis which is an easy and economical method. The structural properties of the produced films were examined by XRD and SEM analyses. Besides, Al/VO_x/p-Si metal-oxide-semiconductor (MOS) structure was obtained by the same synthesis method. Doping densities of these MOS structures were calculated from frequency dependent capacitance–voltage measurements. It was determined that the interface states which were assigned with the help of these parameters vary according to frequency.     

Synthesis and characterization of low particle size nanocrystalline SnSe thin films

Tin selenide (SnSe) nanocrystalline thin films of different thickness from 15 to 70 nm were prepared by inert gas condensation technique. Argon gas flow and substrate temperature were kept constant during deposition process at 2 × 10^?3 Torr and 27 °C respectively. Polycrystalline orthorhombic phase structured was deduced for the prepared SnSe ingot powder by X-ray diffraction pattern. The grazing incident in-plane X-ray diffraction (GIIXD) pattern showed nanocrystalline orthorhombic structure for deposited SnSe thin film. The TEM micrographs showed that thin films were nanocrystalline with particle size in the range from 2 to 5.7 nm. The optical band gap E_g of the thin films due to direct allowed transition have values ranging from 2.5 to 2.13 eV as the particle size increases from 2 to 5.7 nm. The photoconductivity spectra of the nanostructured SnSe thin films of different particle size showed transitions at 2.45, 2.34 and 2.21 eV for films of different particle size.     

Synthesis and thermoelectric/electrical characterization of electrodeposited SbxTey thin films

Sb_xTe_y films were potentiostatically electrodeposited from acidic nitric baths at room temperature by controlling the applied potential. Near-stoichiometric Sb₂Te₃ thin films were obtained at applied potentials between ?0.15 and ?0.30 V vs. saturated calomel electrode (SCE). Post-annealing in a reducing environment resulted in an improvement in the crystal structure without the evaporation of the Te element. This result was indicated by a significant reduction in the electrical resistance and decrease in the FWHM of the main diffraction peaks. The power factor (σS²) increased from 44.2 to 372.1 μW/m K² after annealing at 473 K.     

Synthesis and characterization of Nb2AlC thin films

We report on the synthesis and characterization of epitaxial c-axis oriented Nb₂AlC thin films deposited on c-axis sapphire (Al₂O₃) substrates by magnetron sputtering. Selected area electron diffraction reveal that independent of substrate temperature or film stoichiometry, there is the growth of a secondary phase not found in bulk, Nb₅Al₃C_x with a- and c-axis lattice constants of 7.746 Å and 5.246 Å, respectively. Scanning electron micrographs reveal large surface features, many with hexagonal shape and faceted texture. Atomic force microscopy topographical measurements indicate a surface roughness of approximately 15% of the total film thickness. Electrical transport measurements show typical metal-like conduction with a room temperature resistivity of ≈ 0.9 μΩ-m and a residual resistivity ratio of 2.5. A superconducting transition was found at ≈ 440 mK.     

Sn膜硫化合成SnS薄膜及其性能研究

用热蒸发法技术在ITO透明导电玻璃上沉积一层Sn膜，将其装入石墨盒里后，放在真空炉里面硫化处理，硫化温度在150-350℃之间。通过对在不同温度下硫化的薄膜进行结构、成分和表面形貌分析，表明退火温度在230-250℃之间时所制得的薄膜为正交结构的SnS多晶薄膜，其均匀性和对基片的附着力都较好，具有（111）方向优先生长，薄膜粒径在200-800nm。通过测量薄膜样品的反射和透射光谱，计算得到其直接禁带宽度Eg=1．38eV，在基本吸收边附近的吸收系数大于10^4／cm，用霍尔测量系统测得其导电类型为P型，适合应用于太阳能电池的吸收层材料。     

Manganese ferrite thin films Part I: Preparation and structure

The preparation of manganese ferrite thin films by the reactive evaporation of oxidic materials is reported. The process is not critical and provides homogeneous mirror-like films with spinel structure. An annealing procedure below 750 °C has a strong influence on the properties of the films. Special attention is paid to the partial oxygen pressure during the annealing process. For this purpose data are collected from the literature concerning the equilibrium conditions of the spinel structure for varying manganese-iron contents. The lattice constant of the spinel structure of the films is determined by electron diffraction.     

Superparamagnetic properties of thin films and small particles of magnesium ferrite

The magnetic properties of superparamagnetic thin films and small particles of magnesium ferrite obtained by thermal treatment of the iron films evaporated in vacuum on the     

Preparation and gas-sensing characteristics of nanocrystalline spinel zinc ferrite thin films

Zinc ferrite is a promising sensor material. In this paper, thin films of nanocrystalline zinc ferrite were deposited on alumina substrates by nebulization of a 0.01-M solution of a mixture of ZnCl/sub 2/ and FeCl/sub 3/ in ethanol (Zn:Fe=1:2) followed by pyrolysis and annealing in flowing air. The resulting films were characterized by X-ray diffraction and scanning electron microscopy, and the gas-sensing properties of as-deposited films were also investigated.     

Magnetic and electrical properties of metal/ferrite composite thin films

Abstracts are not published in this journal This revised version was published online in November 2006 with corrections to the Cover Date.