Thermoluminescence of (ZnS∶CdS∶Ag∶Ni∶Co) phosphors

The doping of (ZnSCdSAgNi) phosphors with cobalt impurity results in new phosphors with thermoluminescence curves showing five distinct peaks. Four of these peaks are associated with chlorine, cadmium, cobalt and nickel impurities and have energy depths of 0·26 eV, 0·52 eV, 0·53 eV and 0·78 eV respectively. The fifth peak, appearing at high cobalt concentrations, has an energy depth of 1·09 eV and is attributed to the formation of (Co⁺⁺ - Ag^–) associates. The emitted thermoluminescence consists of two bands: one in the yellow and the other in the red spectral region. The yellow band subsumes the chlorine, cadmium and cobalt peaks and is due to recombination processes occurring through silver centres. The red band, on the other hand, includes the nickel and the (Co⁺⁺-Ag^–) peaks. The appearance of the nickel peak in the red band is explained by recombination processes at energy levels created by the nickel impurity centres.     

Electronic Structure and Exchange Interactions in RNi<Subscript>4</Subscript>Co (R = Eu,Yb) Compounds

The electronic structure and the exchange interactions in EuNi₄Co and YbNi₄Co compounds have been calculated in terms of a theoretical approach with the inclusion of electronic correlations (LSDA + U method); the variants of substitution of cobalt ion for nickel in the 3d lattice in both types of crystallographic positions 2c and 3g are considered. The total energies obtained in self-consistent calculations show that individual cobalt impurities are more preferably arranged in position of the 3g type. A Co ion in RNi₄Co (R = Eu, Yb) is characterized by a significant magnetic moment, which leads to significant increase in the exchange interaction of Co and Ni ions in the 3d metal sublattice.     

不同催化剂热解法制备硼碳氮纳米管过程中的影响

对以钴、镍、钴/镍、钴/二茂铁、镍/二茂铁和二茂铁为催化剂高温热解法制备的硼碳氮（BCN）纳米管的结构、产率等的影响进行了分析.实验中发现催化剂在BCN纳米管的生长过程中有重要作用.高分辨率透射电子显微镜图像显示在860℃时，以镍/二茂铁、钴/二茂铁为催化剂生成的BCN纳米管具有“竹节状”结构，且管壁较薄，镍、钴或镍/钴作催化剂生成的BCN纳米管不具有明显的“竹节状”结构，管壁较厚，且粗细不均匀，而以二茂铁作催化剂没有BCN纳米管生成.在所有生成的BCN纳米管中含有催化剂颗粒.通过对生成的BCN纳米管的结 关键词： BCN纳米管 热解 催化剂 拉曼光谱     

Mass-filtered cobalt clusters in contact with epitaxially ordered metal surfaces

Mass-filtered cobalt clusters with a size between 5 nm and 12 nm have been deposited in situ under soft-landing conditions onto epitaxially ordered iron and nickel films. The spin and orbital moments of both the clusters as well as the substrate films have been investigated using the element-specific method of X-ray magnetic circular dichroism in photoabsorption. Here, the ferromagnetic films with in-plane magnetic anisotropies have been used to magnetize the clusters remanently without applying external magnetic fields during the measurements. Experimental results from the cobalt clusters are discussed with respect to the different substrates. Furthermore, the influence of oxygen exposure on the spin and orbital moments of cobalt clusters has been investigated in in situ oxidation experiments. PACS 73.22.-f; 75.70.-i; 75.75.+a; 81.07.-b     

Magnetic properties and structure of cobalt films prepared by chemical precipitation

The magnetic properties of chemically precipitated cobalt films are found to depend on solution composition. The films have the hexagonal -Co structure. A qualitative explanation of the magnetic properties is given.     

Thin films of magnesium oxide prepared by plasma-enhanced chemical vapour deposition

Thin films of magnesium oxide have been deposited on glass, quartz, stainless steel, and nickel by plasma enhanced chemical vapour deposition using 2,2,6,6-tetramethyl-heptanedionato-3,5-magnesium(II) (Mg(thd)₂) as precursor. The films show (100)-orientation when deposited at temperatures 673 K. The influence of experimental parameters on deposition rate and film properties has been studied.On leave from the Beijing Solar Energy Research Institute, Beijing, China     

Hyperbolic Medium of Finite-Length Wires

K-shell X-ray fluorescence parameters of low Z elements cobalt, nickel, copper, and zinc have been measured employing a simple method. These elemental targets were excited by using 32.86 keV barium K X-ray photons from a weak ¹³⁷Cs γ-ray source, and the emitted K-shell X-rays from these targets were detected using a low-energy high-purity germanium X-ray detector spectrometer. The results are compared with the standard theoretical, semi-empirical, fitted values and with the others’ experimental values.     

Optical properties of nickel(II)-azo complexes thin films for potential application as high-density recordable optical recording media

Smooth thin films of three kinds of nickel(II)-azo complexes were prepared by the spin-coating method. Absorption spectra of the thin films on K9 glass substrate in the 300-600 nm wavelength region were measured. Optical constants (complex refractive index ) and thickness of the thin films prepared on single-crystal silicon substrate in the 300-600 nm wavelength region were investigated on rotating analyzer-polarizer type of scanning ellipsometer, and dielectric constants , absorption coefficients α as well as reflectance R of thin films were then calculated at 405 nm. In addition, in order to examine the possible use of nickel(II)-azo complex thin film as an optical recording medium, one of the nickel(II)-azo complex thin film prepared on K9 glass substrate with an Ag reflective layer was also studied by atomic force microscopy and static optical recording. The results show that the nickel(II)-azo complex thin film is smooth and has a root mean square surface roughness of 2.25 nm, and the recording marks on the nickel(II)-azo complex thin film are very clear and circular, and their size can reach 200 nm or less.     

Structural and magnetoelectric properties of MFe<Subscript>2</Subscript>O<Subscript>4</Subscript>–PZT (M = Ni,Co) and La<Subscript>x</Subscript>(Ca,Sr)<Subscript>1-x</Subscript>MnO<Subscript>3</Subscript>–PZT multilayer composites

Thick-film layered magnetoelectric composites consisting of ferromagnetic and ferroelectric phases have been synthesized with nickel ferrite (NFO), cobalt ferrite, La_0.7Sr_0.3MnO₃ (LSMO), or La_0.7Ca_0.3MnO₃ (LCMO) and lead zirconate titanate (PZT). Structural, magnetic, and ferromagnetic resonance characterization shows evidence for defect-free ferrites, but deterioration of manganite parameters. The resistivity and dielectric constants are smaller than expected values. The magnetoelectric effect (ME) is stronger in ferrite–PZT than in manganite–PZT. The ME voltage coefficient _E at room temperature is the highest in NFO–PZT and the smallest for LCMO–PZT. The transverse ME effect is an order of magnitude stronger than the longitudinal effect. The magnitude of _E correlates well with magnetic permeability for the ferrites. PACS 75.80.+q; 75.70.Gg; 75.60.-d     

Correlation effects in 3d transition metals: Presence of a two-hole core-satellite in cobalt

Photoemission spectra of the 2p-level have been recorded from evaporated films of the 3d transition metals vanadium, chromium and cobalt. Structures on the high binding energy side of the spectra are observed; cobalt shows a weak satellite structure that resembles the well-known shakeup satellite in the nickel core level spectrum, only less intense, whereas the core level spectra of V and Cr only show satellites due to collective electron excitations.     

Zur Erniedrigung des Sättigungsmoments von Nickel durch chemisorbierten Wasserstoff

The decrease of the magnetic saturation moment of superparamagnetic nickel particles of 30 Å radius by hydrogenation was investigated, and proved to be?=0.72 Bohr magnetons per hydrogen atom chemisorbed. This is the same amount that has been reported byDietz andSelwood for 64 Å particles. From this the conclusion may be drawn that most probably the effect does not depend on particle size. Interpreting the result in Pauling’s model of the covalent bond, one may conclude the Ni-H-chemisorption bond to have about 14% ionic character. This seems reasonable in view of the difference in electronegativity between hydrogen and nickel surface, but one of the assumptions of the model seems to be not safely fulfilled as will be discussed. On the other hand one may conceive chemisorption to be the first step towards formation of nickel hydride at the particle surface. Doing so, the comparison of the found result for? with recent experiments on thick nickel films electrolytically loaded with hydrogen yields a satisfactory result.     

The influence of thermal diffusion on laser ablation of metal films

Single-shot ablation thresholds of nickel and gold films in the thickness range from 50 nm to 7 m have been measured for 14 ns laser pulses at 248 nm, using photoacoustic shock wave detection in air. The metal films were deposited on fused silica substrates. The ablation threshold was found to increase linearly with film thickness up to the thermal diffusion length of the film. Beyond this point it remains independent of film thickness. The proportionality between threshold fluence and thickness allows the prediction of ablation thresholds of metal films from the knowledge of their optical properties, evaporation enthalpies and thermal diffusivities. Physically it proves that ablation is driven by the energy density determined by the thermal diffusion length. A simple thermodynamic model describes the data well. Thermal diffusivities, an essential input for this model, were measured using the technique of transient thermal gratings. In addition, the substrate dependence of the ablation threshold was investigated for 150 nm Ni films.     

XPS investigation of LPE garnet films

XPS spectra of YIG, YIG:Bi, YIG:Ca and YIG:Co(Ge, Ca) epitaxial garnet films were measured at room temperature. The positions of the main iron, yttrium, oxygen, bismuth, cobalt and lead spectral lines were determined and their changes with the surface treatments were investigated. It was found that divalent and trivalent states of iron and cobalt ions can be resolved, the chemical shifts being in oposite directions.The authors would like to thank Dr. J. imová for careful EPMA analysis of the samples.     

Improvement of the efficiency of phthalocyanine organic Schottky solar cells with ITO electrode treatment

The devices investigated in this work consisted of an indium tin oxide (ITO)-coated glass substrate, phthalocyanine (Pc) layer and an aluminum electrode. The Schottky cell exhibits optimal performance with one ohmic and one barrier contact. The work function of the ITO film is typically around 4.5–4.8 eV, while the HOMO level of phthalocyanine films is typically around 5.2 eV. It is known that surface treatment of ITO can change its work function. We investigated various ITO surface treatments for improving the performance of phthalocyanine-based Schottky solar cells. We found that cells of ITO treated with HCl and UV ozone exhibited the best performance. Four different phthalocyanines (Pcs), namely nickel phthalocyanine (NiPc), copper phthalocyanine (CuPc), iron phthalocyanine (FePc) and cobalt phthalocyanine (CoPc) were investigated. A power conversion efficiency as high as 10% was achieved for the CuPc cell with monochromatic excitation at 632.8 nm, with a light intensity of 2.7 W/cm². PACS 72.40.+w; 73.61.Ph     

Magnetostriction in porous nickel films

Conclusions A new type of magnetostriction has been found in porous metal-ceramic nickel films. The magnetostriction differs from that of compact nickel in that it is positive, does not saturate in fields up to 1400 Oe and exceeds ^s of nickel by several times.The existence of the negative magnetic charge striction and positive tensomagnetostriction proposed in this work was experimentally proved in model designed samples.It was proved experimentally that the magnetostriction of manufactured articles depends not only on ^s of the material, but also on the relative alignment and configuration of their parts.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 141–143, July, 1972.     

Direct ion beam deposition of polymeric styrene films and in situ characterization by electron spectroscopy

Polymeric styrene films with thicknesses ranging from about one nm up to a few m have been deposited by means of a direct ion beam deposition (IBD) technique. The deposition energy, which can be chosen independently of the parameters which govern the plasma conditions, has been varied between few eV and 1000 eV. The correlation between the deposition parameters and the resulting film properties in terms of the electronic structure is discussed. The in situ characterization by electron spectroscopy has proved to be a very useful characterization method and ultraviolet photoelectron spectroscopy in particular revealed an extremely high sensitivity to structural differences in the deposited films. The polymeric films have also been characterized by scanning electron microscopy and optical spectroscopy. These techniques have also served to compare films prepared by the direct IBD technique with films obtained by standard rf plasma polymerization (RFPP) in a tubular reactor. Significant differences have been found which are dependent on the deposition parameters; these are discussed in detail.Department of Chemical Engineering, Beijing Institute of Technology, P.O. Box 327 Beijing, 100081 Beijing, P.R. China     

Magneto-optic phenomena in metastable Fe-Cu solid solutions

It has been observed by the transverse Kerr effect that the hysteresis loop changes its sense and its amplitude due to the composition gradient introduced in the metastable Fe-Cu solid solution, which has been produced by quenching from the vapour phase. The phenomenon was interpreted in terms of skin depth effect which plays an important role due to the significantly lowered density of such films relative to the bulk value.The calculated values of skin depth effect were found to be in fairly good agreement with experimentally obtained thicknesses of iron and copper films, respectively. Metastable Fe-Cu solid solution films appeared to have a quasi-sandwich structure due to the presence of very strong composition gradient within the relatively short thickness range.     

Structural and magnetic properties of high magnetic moment electroplated CoNiFe thin films

CoNiFe alloy thin films deposited at various cobalt concentrations were galvanostatically electrodeposited on the pre-cleaned copper substrates. The effects of cobalt concentration on the structural, compositional, morphological, and magnetic properties of the films were investigated. X-ray diffraction patterns revealed that the deposited films possess polycrystalline in nature with mixed (fcc–bcc) cubic structure at optimized cobalt concentration. Microstructural properties of the films were calculated from predominant diffraction lines. The surface morphology and surface roughness were characterized using scanning electron microscopy and atomic force microscopy, respectively. EDAX results were revealed that the cobalt content increases as nickel content decreases whereas ferrous content initially increases and then eventually decreases in the CoNiFe alloy. VSM results show a higher value of saturation magnetization (4πM _s) above 2 T with coercivity 154 A/m for films deposited in the optimized deposition condition.     

Corrosion of stainless steels in chloride solution: An XPS investigation of passive films

Five commercial steels ranging from the martensitic stainless steel containing 12% chromium to the superferrite containing 29% chromium, 4% molybdenum, and 2% nickel have been studied by XPS. In addition, a pure iron-chromium alloy containing 7% chromium has been investigated. Armco iron and pure chromium (99.99%) were included as references. The formation of the passive films (or corrosion) occurred in deoxygenated 0.1 M NaCl solution (pH=5.6), from which the samples were transferred directly to the XPS chamber under controlled atmosphere (Ar). Concentration profiles (at.-%) of the alloy constituents in their oxidized and metallic states have been determined separately from the measured XPS depth profiles. Forc= 12% chromium the passive films have the following structure: there is a depletion of Cr in the inner region, followed by an enrichment (concentration maximum) in the central region of the films. The height of this maximum increases, and its position shifts towards the surface with increasing chromium content in the alloy. The outermost monolayers are rich in water and hydroxyl groups. Various significant properties of the films change drastically at the critical chromium concentration of about 12%. This behaviour is rather independent of the other components (Mo, Ni, Cu) present in the alloys and is discussed in terms of a phase transition in the films which is controlled by the chromium concentration.