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1.
A original method of synthesis of quasi-one-dimensional Ti1 − x V x (OCH2CH2O)2 (0 ≤ x ≤ 0.13) and Zn1 − x Co x (HCOO)(HOCH2CH2O) (0 ≤ x ≤ 0.3) has been developed. The synthesis products were used as a basis for nanoscale extended Ti1 − x V x O2 and Zn1 − x Co x O oxides. The compounds obtained and products of their thermolysis were investigated by X-ray diffraction, microscopy, IR spectroscopy, thermogravimetry, and chemical analysis; the shape and size of particles were determined by scanning electron microscopy. The good prospects of Ti1 − x V x O2 and Zn1 − x Co x O solid solutions as photocatalysts for hydroquinone oxidation are shown.  相似文献   

2.
By the electrospinning and calcination techniques, we have prepared uniform nanofibers of Co1−x Zn x Fe2O4 (0.0≤x≤0.5) ferrites with diameters of 110–130 nm. The Co1−x Zn x Fe2O4 nanofibers are single-phase spinels and the lattice constant with Zn content deviates from the Vegard’s law for these Co1−x Zn x Fe2O4 nanofibers. The Co1−x Zn x Fe2O4 nanocrystal grains by which are built nanofibers increase with calcination temperature. Variations of coercivity and saturation magnetization with calcination temperature can be explained in terms of the grain-size (D) effect. The coercivity (H c) of Co0.5Zn0.5Fe2O4 nanofibers varies as D 0.65 and basically follows the predicted D 2/3 dependence based on the random anisotropy model in a D range below the single-domain size around 40 nm. The saturation magnetization of Co1−x Zn x Fe2O4 nanofibers initially increases with increasing Zn content, reaches a maximum value at x=0.3 and then decreases with further increase of Zn content, while the coercivity exhibits a continuous reduction with the increase of Zn content.  相似文献   

3.
In this paper, we report on the pulsed laser deposition of epitaxial (0002) oriented Zn1−x Mg x O thin films onto (0001) sapphire substrate in O2 ambient at different deposition temperatures. Pulsed laser deposited Zn1−x Mg x O films showed (0002) oriented hexagonal wurtzite structure up to 34% of Mg concentration. The bandgap of Zn1−x Mg x O thin films is successfully tuned from 3.3 to 4.2 eV by adjusting the Mg concentration x=0.0 to x=0.34. Pulsed laser deposited Zn1−x Mg x O thin films were characterized by XRD, AFM, SEM, PL and UV–VIS spectrometer. We have also studied the effect of deposition temperature on to the structure, surface morphology and optical properties of Zn1−x Mg x O thin films.  相似文献   

4.
Thin films of Cd y Zn1 − y O and Mg x Zn1 − x O (y = 0−0.35, x = 0−0.45) ternary alloys have been grown by pulsed laser deposition onto sapphire substrates. The record solubility limits of Cd (y = 0.3) and Mg (x = 0.35) have been achieved in hexagonal zinc oxide. The mismatch of the lattice parameters a of Cd0.2Zn0.8O and Mg0.35Zn0.65O does not exceed 1%; in this case, the band gap discontinuity is 1.3 eV. The surface roughness of the films does not exceed 2.5 nm at x = 0−0.27 and y = 0−0.20.  相似文献   

5.
The Mg- and In-doped zinc oxide (Mg x Zn1−x O, In y Zn1−y O) nanoparticles were successfully prepared by flame spray synthesis method. According to the results obtained from X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV–Vis absorption spectra, it was concluded that the Mg or In doping induced the lattice constants to change to some extent; the band gap of Mg x Zn1−x O also increased with respect to the decreasing band gap of In y Zn1−y O. Moreover, the strong UV emission and weak visible emission were investigated by photoluminescence spectra, while the mechanisms of Mg or In doping on PL spectra have been discussed in detail.  相似文献   

6.
This is a report of an X-band electronic paramagnetic resonance (EPR) study of Zn1−x Co x O (x = 1 and 3%) powders at various temperatures (10–200 K). EPR spectroscopy is a powerful tool to study the complex magnetic state and the Co ionic state, their local environment and interactions as well. These samples are interesting to study in order to understand how ‘Co doping’ produces ferromagnetism in ZnO2, making it a promising ferromagnetic semiconductor at room temperature.  相似文献   

7.
Thin films of Mg x Zn1−x O and Mg x Zn1−x O doped with nitrogen were deposited by Radio Frequency plasma beam assisted Pulsed Laser Deposition (RF-PLD) in oxygen or oxygen-nitrogen discharge with different nitrogen/oxygen ratios. A Nd:YAG laser working at a wavelength of 266 nm, having a 10 Hz repetition rate was used for the depositions. The energy density of the incident beam was 3 J/cm2 and the RF power was set to 100 W for all the samples. X-ray Diffraction (XRD) and Spectroscopic Ellipsometry (SE) were employed to investigate the samples. The degree of crystallinity is fount to decrease with increasing the Mg concentration, while the solubility of Mg in ZnO increases by 30% in the N-doped Mg x Zn1−x O thin films grown by RF-PLD. Segregation of MgO phase at a Mg concentration of 30% for Mg x Zn1−x O thin film is detected both by XRD and SE. The band gap of the samples increases from 3.37 up to 3.57 eV with increasing the Mg concentration and the nitrogen/oxygen ratio for each Mg concentration. A dependence of the dielectric function (refractive index) on both stoichiometry and degree of crystalinity is also found, the refractive index having values between 1.7 and 2 in visible spectral range.  相似文献   

8.
Zn1−xCoxO (0 ≤ x ≤ 0.15) thin films grown on Si (1 0 0) substrates were prepared by a sol-gel technique. The effects of Co doped on the structural, optical properties and surface chemical valence states of the Zn1−xCoxO (0 ≤ x ≤ 0.15) films were investigated by X-ray diffraction (XRD), ultraviolet-visible spectrometer and X-ray photoelectron spectroscopy (XPS). XRD results show that the Zn1−xCoxO films retained a hexagonal crystal structure of ZnO with better c-axis preferred orientation compared to the undoped ZnO films. The optical absorption spectra suggest that the optical band-gap of the Zn1−xCoxO thin films varied from 3.26 to 2.79 eV with increasing Co content from x = 0 to x = 0.15. XPS studies show the possible oxidation states of Co in Zn1−xCoxO (0 ≤ x ≤ 0.05), Zn0.90Co0.10O and Zn0.85Co0.15O are CoO, Co3O4 and Co2O3, with an increase of Co content, respectively.  相似文献   

9.
Zn1−x B x O (0≤x≤0.04) thin films were deposited by the liquid source misted chemical vapor deposition (LSMCD) method. The thin films were polycrystalline with grain sizes of 16 nm to 22 nm. The structural, optical, and electrical properties were investigated by X-ray diffraction, UV-visible spectrophotometry, Raman spectroscopy, and Hall effect measurement. Also scanning electron (SEM) and atomic force microscopy (AFM) techniques were used in order to determine the morphological and topological characteristics of the films. The optimal result of Zn1−x B x O films was obtained at x=0.02, with a low resistivity of ≈10−2 Ω cm, and a high transmittancy of 85% in the visible light spectrum (300 nm ∼ 800 nm).  相似文献   

10.
(Co, Zn)O compound has been obtained by a non-expensive synthesis route. ZnTe thin films were obtained by isothermal close space sublimation on the Co thin layer previously sputtered on silicon substrates. After the annealing process in humid ambient cobalt atoms diffusion and Zn oxidation were obtained besides partial Te evaporation. The detailed characterization of the samples by using XRD, RBS, AFM, XPS, VSM and MFM techniques point to the formation of room temperature ferromagnetic Co x Zn(1−x)O phase (x<0.15). This ferromagnetic behavior is mainly attributed to Co atoms substituting Zn atoms in the ZnO network.  相似文献   

11.
Recently, we have demonstrated the successful synthesis of Fe x Co1−x /Co y Fe3−y O4 nanocomposites with various alkaline solutions by using surfactants-assisted-hydrothermal (SAH) process. In this article, the synthesis of Fe x Co1−x /CoyFe3−y O4 nanocomposites with their sizes varying between 20 nm and 2 μm was reported. X-ray powder diffraction (XRD) analyses showed that the surfactants, pH, precipitator, and temperature of the system play important roles in the nucleation and growth processes. The magnetic properties tested by vibrating sample magnetometer (VSM) at room temperature exhibit ferromagnetic behavior of the nanocomposites. These Fe x Co1−x /Co y Fe3−y O4 nanocomposites may have a potential application as magnetic carriers for drug targeting because of their excellent soft-magnetic properties.  相似文献   

12.
This article describes the synthesis of highly water-soluble Zn x Hg1−x Se y S1−y quantum dots (QDs) in aqueous solution through a simple photo-assisted reaction between ZnSe QDs and mercury(I) nitrate dihydrate [Hg2(NO3)2·2H2O]. In order to deduce the optimal synthesis conditions, we varied several parameters, including the concentrations of mercaptosuccinic acid (MSA) and Hg2(NO3)2·2H2O, the illumination time, and the reaction temperature. When irradiated at temperatures below 80 °C, the ZnSe QDs reacted with the S2− ions formed rapidly from MSA and the Hg2+ ions formed from Hg2 2+ ions to form Zn x Hg1−x Se y S1−y QDs through a process of photo-etching and surface combination. Under different conditions, we prepared a series of Zn x Hg1−x Se y S1−y QDs that emit fluorescence at the maximum wavelengths ranging from 405 to 760 nm. Inductively coupled plasma-mass spectrometry and transmission electron microscopy/energy dispersive spectrometry revealed that the content of Hg in the Zn x Hg1−x Se y S1−y QDs was greater when the synthesis was conducted at higher temperature. The Zn0.88Hg0.12Se0.44S0.56 QDs exhibit improved photostability than crude ZnSe QDs and possess long lifetimes (τ1 ~ 38 ns and τ2 ~ 158 ns).  相似文献   

13.
The multi-walled carbon nanotubes (MWCNTs) wrapped with hexagonal wurtzite Zn x Cd1−x S nanoparticles with a uniform and small diameter have been prepared to form Zn x Cd1−x S–MWCNT heterostructures by microwave-assisted route using Zn(Ac)2, Cd(NO3)2, and thioacetamide as the reactants. The heterostructures have been characterized by X-ray powder diffraction, scanning and transmission electron microscopy, high-resolution transmission electron microscopy, photoluminescence (PL) and PL excited lifetime. Despite the analogous size and configuration, the Zn x Cd1−x S–MWCNT (x = 0, 0.2, 0.5, 0.8, 1) with different Zn concentration exhibit composition-dependent absorption properties in the visible zone. The PL peak positions of Zn x Cd1−x S–MWCNT change gradually from ZnS–MWCNT to CdS–MWCNT. The Zn x Cd1−x S–MWCNT shows different photocatalytic activity towards the photodegradation of fuchsin acid under visible light illumination, photocatalytic activity of the Zn x Cd1−x S–MWCNT decreases gradually with the increase in the Zn concentration, the Zn0.2Cd0.8S–MWCNT possessed the best photocatalytic activity. After recycling thrice, the photocatalysts still have about 85% efficiency.  相似文献   

14.
We report on the analysis of optical transmittance spectra and the resulting ferromagnetic characteristics of sputtered Zn1−xCoxO films. Zn1−xCoxO films were prepared on (0001)-oriented Al2O3 substrates by the radio-frequency (rf) magnetron co-sputtering method. The XRD results showed that the crystallinity of films was properly maintained up to x=0.30 and no second phase peaks were detected up to x=0.40. The transmittance spectra showed both the increase of the absorption band intensity and the red shift of the absorption peak as well as the band edge with increasing x. We have proved experimentally that these changes depend on Co concentration. These optical properties suggest that sp-d exchange interactions and typical d-d transitions become activated with increasing x, which leads to the enhancement of ferromagnetic properties in Zn1−xCoxO films as shown in the AGM results. Therefore, it is concluded that the ferromagnetism derives from the substitution of Co2+ for Zn2+ without changing the wurtzite structure.  相似文献   

15.
Single-phase Zn1−xCoxO (0.02≤x≤0.08) dilute magnetic semiconductor is prepared by mechanical milling process. The shift of XRD peaks towards the higher angle and a redshift in the band gap compared to the undoped ZnO ensure the incorporation of Co2+ ions in the semiconductor host lattice. Pure ZnxCo1−xO phases show the paramagnetic behavior in the temperature range 80 K≤T≤300 K. The room temperature volume magnetic susceptibility (χv) estimated in case of Zn0.96Co0.04O is ∼10−5 emu/Oe cm3. The temperature dependence of susceptibility χv can be fitted well with Curie law confirming the paramagnetic interaction. The observed crystal-field splitting of 3d levels of Co2+ ions inside Zn1−xCoxO has been successfully interpreted using Curie law.  相似文献   

16.
Results are presented of the first measurements of infrared reflection spectra of Zn1−x CdxSe films (x=0–0.55; 1) grown on a GaAs substrate by molecular-beam epitaxy. It is shown by a mathematical analysis of the experimental spectra that the investigated Zn1−x CdxSe alloy system manifests a unimodal rearrangement of its vibrational spectrum as the composition is varied. Fiz. Tverd. Tela (St. Petersburg) 41, 982–985 (June 1999)  相似文献   

17.
利用X射线吸收精细结构、X射线衍射和磁性测量等技术研究脉冲激光气相沉积法制备的Zn1-xCoxO (x=0.01,0.02)稀磁半导体薄膜的结构和磁性.磁性测量结果表明Zn1-xCoxO样品都具有室温铁磁性.X射线衍射结果显示其薄膜样品具有结晶良好的纤锌矿结构.荧光X射线吸收精细结构测试结果表明,脉冲激光气相沉积法制备的样品中的Co离子全部进入ZnO晶格中替代了部分Zn的格点位置,生成单一相的Zn1-xCoxO 稀磁半导体.通过对X射线吸收近边结构谱的分析,确定Zn1-xCoxO薄膜中存在O空位,表明Co离子与O空位的相互作用是诱导Zn1-xCoxO产生室温铁磁性的主要原因. 关键词: 1-xCoxO稀磁半导体')" href="#">Zn1-xCoxO稀磁半导体 X射线吸收精细结构谱 脉冲激光气相沉积法  相似文献   

18.
Sr1−x La x Zn x Fe12−x O19/poly(vinylpyrrolidone) (PVP) (0.0≤x≤0.5) precursor nanofibers were prepared by the sol–gel assisted electrospinning method from starting reagents of metal salts and PVP. Subsequently, the Sr1−x La x Zn x Fe12−x O19 nanofibers with diameters of around 100 nm were obtained by calcination of the precursor at 800 to 1000°C for 2 h. The precursor and resultant Sr1−x La x Zn x Fe12−x O19 nanofibers were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectrometer and vibrating sample magnetometer. The grain sizes of Sr0.8La0.2Zn0.2Fe11.8O19 nanofibers are in a nanoscale from 40 to 48 nm corresponding to the calcination temperature from 800 to 1000°C. With La–Zn substitution content increase from 0 to 0.5, the grain size and lattice constants for the Sr1−x La x Zn x Fe12−x O19 nanofibers obtained at 900°C show a steady reduction trend. With variations of the ferrite particle size arising from the La–Zn substitution, the nanofiber morphology changes from the necklace-like structure linking by single elongated plate-like particles to the structure building of multi-particles on the nanofiber cross-section. The specific saturation magnetization of Sr1−x La x Zn x Fe12−x O19 nanofibers initially increases with the La–Zn content, reaching a maximum value 72 A m2 kg−1 at x=0.2, and then decreases with a further La–Zn content increase up to x=0.5, while the coercivity exhibits a continuous reduction from 413 (x=0) to 219 kA m−1 (x=0.5). The mechanism for the La–Zn substitution and the nanofiber magnetic property are analyzed.  相似文献   

19.
The specific features of the structure and the spin system of a lightly doped Zn1 − x V x Te (x = 0.0002) crystal have been investigated for the first time using thermal neutron diffraction and magnetic measurements. The results of these experiments have been discussed in a close connection with the previously obtained information on neutron diffraction and magnetism in Zn1 − x V x Se (x = 0.0018) and Zn1 − x Cr x Se (x = 0.0029, x = 0.0450) single crystals.  相似文献   

20.
Co0.2AlxZn0.8−xO films prepared with different molar ratio of aluminum nitrate to zinc acetate were deposited on substrates by the sol-gel technique. X-ray diffraction, photoluminescence and ferromagnetism measurements were used to characterize the Co0.2AlxZn0.8−xO diluted magnetic semiconductors. The authors found that the intensity of the acceptor-related photoluminescence increased with increasing aluminum concentration and an increase in the number of the acceptor-like defects (zinc vacancies especially) in the Co0.2AlxZn0.8−xO film might lead to the enhancement of the magnetic properties. This implies that controls of the aluminum concentration and the number of the acceptor-like defects are important factors to produce strong ferromagnetism Co0.2AlxZn0.8−xO films prepared by the sol-gel method.  相似文献   

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