Micro-crystals of cuprous oxide with different morphologies were prepared by a hydrothermal process with copper sulfate and
sodium lactate as precursors. Morphology of cuprous oxide was simply controlled by adjusting solution pH values or addition
of different amounts of organic solvent. Structural properties of all the samples were characterized by X-ray diffraction
and scanning electron microscopy. The growth mechanism of cuprous oxide micro-crystal under different conditions was discussed.
Results show that morphologies of cuprous oxide micro-crystals alter from branched structure to octahedron structure and cube
structure with growth conditions. 相似文献
Atomic-scale oxidation dynamics of Cu2O nanocrystallines (NCs) are directly observed by in situ high-resolution transmission electron microscopy.A two-stage oxidation process is observed:(1)The initial oxidation stage is dominated by the dislocation-mediated oxidation behavior of Cu2O NCs via solid-solid transformations,leading to the formation of a new intermediate CuOx phase.The possible crystal structure of the CuOx phase is discussed.(2) Subsequently,CuOx is transformed into CuO by layer-by-layer oxidation.These results will help in understanding the oxidation mechanisms of copper oxides and pave the way for improving their structural diversity and exploiting their potential industrial applications. 相似文献
The compounds Gd14Cu48Ga3 and Tb14Cu48Ga3 have been synthesized, and their structures have been determined by powder x-ray diffraction (Gd14Ag51 type). 相似文献
Cu59.6Zr36.9Al3.5 alloy are prepared by laser-induced combustion synthesis technology. The microstructure and phases formed of the product is
studied by XRD and TEM. The product consists of mixtures of amorphous and crystalline phases, mainly(α-Zr, Zr2Cu, Zr10Cu7 and Cu8Zr3. The amorphous and nanocrystalline phases content over 50% in volume estimated from the broad peak in the XRD spectrum. TEM
and HRTEM results show that the microstructure is characterized by inhomogeneously distributed amorphous, nano Zr2Cu, relatively gross (∼100 nm) Zr2Cu, and large grain Cu10Zr7. 相似文献
This paper presents modification for a model to retrace magnetic hysteresis loop and calculate hysteresis energy loss (HEL) in YBa2Cu3O7 (YBCO). In comparison with reported experimental results, it is revealed that the modified model could retrace successfully magnetic hysteresis loop for YBCO. As an application of this model, the calculation formula of HEL has been included in this article. The results show also that HEL in YBCO increases by 14% with the addition of the magnetic NiW substrate. This leads to conclude that the type of substrate has an effect on HEL of YBCO. This modified model can help us to explain experimental results and expect the functioning of superconductor tapes. 相似文献
We have developed a procedure for the synthesis of phase-pure α- and β-Cu2V2O7. Thermal analysis and X-ray diffraction demonstrate that the β-phase (monoclinic structure) exists at low temperatures (stability
range 25–610°C), while α-Cu2V2O7 (orthorhombic structure) is stable in the range 610–704°C. The α-phase observed during cooling, in particular at room temperature,
is in a metastable state. The melting of the high-temperature phase γ-Cu2V2O7, which forms between 704 and 716°C, has the highest rate in the range 770–785°S and is accompanied by peritectic decomposition
and oxygen gas release. Subsequent cooling gives rise to four exothermic peaks, one of which (780.9°C) is attributable to
the crystallization of the peritectic melt, one (620.1°C) is due to the γ → α → β phase transformations of Cu2V2O7, and the other two arise from the crystallization of multicomponent low-melting-point eutectics containing α- and β-Cu2V2O7, CuVO3, and other compounds. 相似文献
The T-x phase diagram of the Cu2S-Al2S3 system was achieved experimentally from 35 different mixtures of the binary compounds. The results of powder X-ray diffraction (XRPD), differential thermal analysis (DTA) and microprobe analysis (EPMA) are presented. The ternary phases CuAlS2 and CuAl5S8 were found and their homogeneity regions were established. 相似文献
In this paper, the synthesis of nanocrystalline copper oxides Cu2O and CuO thin films on glass substrates using a pulsed 532 nm Nd:YAG laser is presented. Deposition of films is achieved
at two different substrate temperatures. The influence of substrate temperature on the structural and optical properties of
copper oxide films are discussed and analyzed. The X-ray diffraction (XRD) results show that the deposited films are crystalline
in nature. Films prepared at 300 °C substrate temperature were Cu2O and has (111) and (200) diffracted peaks, while films grown at 500 °C were CuO and has (111) and (020) planes. The morphology
of deposited films were characterized by scanning electron microscope (SEM) and atomic force microscope (AFM). The optical
energy gap of Cu2O and CuO films have been determined and found to be 2.04 and 1.35 eV respectively. 相似文献
We have synthesized a solid solution with the composition Cu3Co0.5Se2 and investigated its structural phase transitions by high-temperature X-ray diffraction on a D8 Advance diffractometer. The results demonstrate that, in the range 100–773 K, the solid solution undergoes two phase transitions: at 560 K, the low-temperature, orthorhombic phase (α) transforms into an intermediate, primitive cubic phase (β); at 765 K, the β-phase transforms into a high-temperature phase (γ, sp. gr. Fm3m). The thermoelectric power, electrical conductivity, and Hall coefficient of the solid solution were measured in the temperature range 80–350 K. The observed temperature variation of its thermoelectric power and conductivity can be accounted for under the assumption that its conduction band has an additional subband due to the cobalt atoms. 相似文献
Cu/Cu2O/SnO2 composites were successfully prepared with a facile microwave synthesis method. The structure of Cu/Cu2O/SnO2 composite was studied by morphology characterizations, such as X-ray diffraction, transmission electron microscopy and high-resolution transmission electron microscopy, which showed that the size of the Cu/Cu2O/SnO2 particles is 20–50 nm. The synthesis mechanism revealed that SnCl4 obstructed between Cu(OH) and ethylene glycol, preventing Cu(OH) being reduced into Cu at high temperature. The photocatalytic property of Cu/Cu2O/SnO2 composite was investigated by degrading the mixed dyestuff under the irradiation of visible light at room temperature. Benefiting from the effect of electron transfer, the photocatalytic performance of the microwave-prepared Cu/Cu2O/SnO2 composite was much better than that of pure Cu2O. The possible photocatalytic mechanism of the Cu/Cu2O/SnO2 composite catalysts was proposed and elaborated in this study. This synthesis of Cu/Cu2O/SnO2 composite may provide a method for other Cu2O/semiconductor composites microwave preparation. 相似文献
Kesterite, Cu2ZnSnS4 (CZTS), is a promising absorber layer for use in photovoltaic cells. We report the use of copper, zinc and tin xanthates in melt reactions to produce Cu2ZnSnS4 (CZTS) thin films. The phase of the as-produced CZTS is dependent on decomposition temperature. X-ray diffraction patterns and Raman spectra show that films annealed between 375 and 475 °C are tetragonal, while at temperatures <375 °C hexagonal material was obtained. The electrical parameters of the CZTS films have also been determined. The conduction of all films was p-type, while the other parameters differ for the hexagonal and tetragonal materials: resistivity (27.1 vs 1.23 Ω cm), carrier concentration (2.65 × 10+15 vs 4.55 × 10+17 cm?3) and mobility (87.1 vs 11.1 cm2 V?1 s?1). The Hall coefficients were 2.36 × 103 versus 13.7 cm3 C?1. 相似文献
First-principles calculations based on the tight-binding linear muffin-tin orbital (TB-LMTO) method are performed to investigate
the occurrence of spin polarization in the alkali-metal oxides (M2O) [M: Li, Na, K, Rb] in antifluorite (anti-CaF2-type) structure with non-magnetic sp (F, Cl, Br and I) dopants. The calculations reveal that non-magnetic substitutional doping at cation site can induce stable
half-metallic ferromagnetic ground state in I2-VI compounds. Total energy calculations show that the antifluorite ferromagnetic state is energetically more stable than
the antifluorite non-magnetic state at equilibrium volume. Ground state properties such as equilibrium lattice constant and
bulk modulus were calculated. The calculated magnetic moment is found to be 2.00 μB per dopant atom. 相似文献
The heat capacity of Cu5SmSe4 has been measured from 80 to 300 K. The results have been used to assess the main thermodynamic functions of Cu5SmSe4: entropy (S0(T) − S0(0)), enthalpy increment (H0(T) − H0(0)), and reduced Gibbs energy (Φ0(T)). 相似文献
Manipulating the alignment of liquid crystals (LCs) is a hot and fundamental issue for their applications in block copolymers, photonics, actuators, biosensors, and liquid-crystal displays. Here, the surface characteristic of Cu2O nanocrystals was well controlled to manipulate the orientation of the LCs. The mechanism of the orientation of the LCs induced by Cu2O nanocrystals was elucidated based on the interaction between the LCs and Cu2O nanocrystals. To comprehensively prove our assumption, different types of LCs (nematic, cholesteric, and smectic) as well as the same type of LCs with different polarities were selected in our system. Moreover, the photomechanical behaviors of the LC polymer composites demonstrated that the alignment of LCs can be effectively manipulated using Cu2O nanocrystals.
Novel porous ternary nanocomposite systems containing reduced graphene oxide (RGO)/polyaniline (PANI)/cuprous oxide (Cu2O) were prepared via one-step in situ redox method. The RGO/PANI/Cu2O nanocomposites present a flower-like structure with an average size of 2.0 μm in diameter. The morphologies and properties of the products can be controlled by adjusting the molar ratios of aniline to Cu2+. When the molar ratio of aniline to Cu2+ is 1:1, the product exhibits excellent microwave absorption property in the frequency range of 2–18 GHz. It can be seen that the maximum reflection loss (RL) of the ternary composite is up to ?52.8 dB at 2.7 GHz with a thickness of only 2 mm, and the absorption bandwidth corresponding to ?10 dB (90% of EM wave absorption) is 13.2 GHz. The microwave absorption property of ternary RGO/PANI/Cu2O composite is significantly improved due to its special flower-like porous structure, dielectric loss property and well impedance matching characteristics, which is 8.12 times than that of pure RGO and 5.28 times than that of pure PANI. Therefore, our study paves a new way to prepare the promising lightweight and high-performance composite materials combined with the characteristics of three components for electromagnetic absorption. 相似文献
Magnetic properties of sintered Eu0.7Sm0.3Ba2Cu3O7?δ were investigated both in dc and ac magnetic fields. The dc response reflects the interplay between the rare earth ion paramagnetic and the superconducting charge carrier subsystems, respectively. The harmonic susceptibilities exhibit special features: the second harmonic is anomalously high and the third harmonic in zero dc-field has reversed temperature dependence with respect to the theoretical models. The magnetic relaxation at low fields is monotonous and occurs as a two-stage relaxation, each stage obeying logarithmical time dependence with different rates. At high fields, the relaxation is nonmonotonous with a peak at intermediate time suggesting a temporary re-entrance of irreversibility when the flux-line density increases in the center of the sample because of the redistribution of the vortices toward that region. 相似文献
The Mg–Cu–Y system is known to be one of the best glass formers among the various existing magnesium alloys. The compositions
chosen for the current study were Mg80Cu15Y5 and Mg80Cu10Y10. Different casting processes yielded four different microstructures that were analyzed by means of X-ray diffraction, scanning
electron microscopy, high resolution scanning electron microscopy, and energy-dispersive X-ray spectroscopy chemical analysis.
The different casting procedures were gravity castings of 3 mm diameter specimens into a copper mold held at different temperatures
(cooled to −195 °C with the aid of liquid nitrogen, held at room temperature and heated up to 300 °C) and melt-spinning. Detailed
microstructure study was then performed on the melt-spun specimen using transmission electron microscopy and high resolution
transmission electron microscopy. The above-mentioned investigation revealed a crystalline rather than amorphous structure.
The observed microstructure could not be explained on the basis of current models referring to the frequency of nucleation
events. 相似文献
ZnIn2S4 and ZnIn2S4:Cu2+ single crystals are shown to exhibit considerable photoconductivity and luminescence anisotropy. The mechanism of carrier
recombination in the crystals is polarization-dependent. Their spectra can be understood in terms of optical transitions involving
donor and acceptor levels. The degree and spectral distribution of the anisotropy can be tuned via doping and alternating
growth of the three- and one-layer polytypes. 相似文献