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1.
The method of thermal neutron diffraction is used to study a structural state of crystal Zn 1 − x
Fe
x
Se ( x = 0.001) obtained in the sphalerite modification. It was found that the diffractive pictures of a cubic crystal contain the
regions of diffuse scattering in the vicinity of Bragg reflections of an initial crystal lattice. It was shown that the diffuse
scattering effects were caused by the local transverse displacements of atoms in a crystal lattice induced by Fe 2+ ions. It is concluded that a static tetragonal-type Jahn-Teller effect exists in a ZnSe alloy doped by magnetoactive iron
ions. 相似文献
2.
The structural state of a Zn 1 ? x Fe x Se ( x = 0.001) crystal has been studied using thermal neutron diffraction. The diffraction patterns of the cubic crystal have been found to contain diffuse scattering regions concentrated in the vicinity of the strong Bragg reflections. It has been shown that the diffuse scattering effects are due to local transverse displacements of the crystal lattice atoms, and these displacements are induced by iron ions that demonstrate the static Jahn-Teller effect of the tetragonal type in the ZnSe compound. 相似文献
3.
The structural state of the cubic Zn 0.999Fe 0.001S single crystal grown by the chemical transport method has been investigated using thermal neutron diffraction at 300 K for the first time. It has been found that the diffraction patterns of the crystal contain diffuse scattering regions with wave vectors q = 0 and $q = (\bar 1/3, 1/3 , 0)2\pi /a$ . The experimental results have been discussed in the context of the available information on neutron diffraction in the Zn 0.999Fe 0.001Se compound. It has been shown that the effects of diffuse scattering are caused by local shear deformations of the metastable cubic lattice of the compound under investigation. 相似文献
4.
In this paper we presented structural and spectroscopic study of zinc silicate powder samples doped with divalent nickel and cobalt ions. Results of the Rietveld structural refinement, combined with optical spectroscopic study and theoretical crystal field calculations, are presented and discussed. X-ray diffraction studies were performed to establish reliable structure of the doped samples; in this way the interionic distances and chemical bond angles in Zn 2SiO 4:Co 2+ and Zn 2SiO 4:Ni 2+ were calculated and are reported for the first time. The room temperature reflection spectra of the prepared samples were measured in a spectral region from 4000 to 50000 cm ?1. The exchange charge model of crystal field has been applied to analyze the experimental spectra and assign all observed details in the spectra to the corresponding electronic transitions between the Co 2+ and Ni 2+ crystal field energy levels. The only input information for the model calculation was the experimentally obtained structural data, which were used for the calculations of the crystal field parameters with subsequent diagonalization of the crystal field Hamiltonian for both ions. Agreement between the calculated and experimentally detected energy levels of impurity ions was good. On the basis of the crystallographic and crystal field studies it was established that there exists a systematic trend of preferential occupation of one out of two possible crystallographic sites (namely, Zn2) for both impurity ions. 相似文献
5.
Local distortions of the crystal lattice of the semiconductor compound Zn 1 − x
Co
x
Se ( x = 0.01) have been investigated using thermal neutron diffraction. It has been found that the diffraction patterns of the
crystal contain regions of diffuse scattering in the vicinity of strong Bragg peaks at 300 K. As the temperature decreases,
the intensity of diffuse scattering effects substantially decreases. Arguments in favor of the assumption that the origin
of the diffuse scattering is caused by the Jahn-Teller vibronic effect are presented. 相似文献
6.
The structural state of bulk cubic Zn 1 ? x Me x 3d Te single crystals ( Me 3d are Jahn-Teller V and Ni ions with concentrations x = 0.0002 and 0.003, respectively) has been studied by thermal neutron diffraction. It has been found that the neutron diffraction patterns of the crystals contain the previously unknown scattering effects due to static deformations of the basal lattice in a wide vicinity of the 3 d ions. 相似文献
7.
The structure of semiconductor crystals Zn 1?x V x 2+ Se ( x = 0.0018) and Zn 1?x Cr x 2+ Se ( x = 0.0006) was studied for the first time using thermal neutron diffraction at 300 and 120 K. The diffraction patterns of the crystals were revealed to contain diffuse scattering regions near the Bragg reflections of the initial cubic lattice. The experimental results are discussed in combination with earlier obtained data on neutron diffraction and propagation of ultrasonic waves in Zn 1?x Ni x 2+ Se ( x = 0.0025) and Zn 1?x Cr x 2+ Se ( x = 0.0029). The diffuse scattering is shown to be due to nanoscale shear strains of the ZnSe lattice. The character of these strains is determined by Jahn-Teller 3 d ions. 相似文献
8.
This research concerns the analysis of the proton and metal ion binding of amide macrocycles of different structures and sizes by potentiometric, 1H NMR and X‐ray diffraction methods. Protonated ligands exist as a 3D network structures. The ligands form 1:1 complexes with heavy metal ions (Cu 2+, Cd 2+, Pb 2+, Zn 2+, and Ni 2+) in aqueous solutions and demonstrate the high selectivity towards Cu 2+ cations. The pyridine‐2,6‐dicarbamide fragment provides structural rigidity to crown ether, resulting the molecule has an open cavity and faster kinetics of metal complexes formation. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
9.
The structural state of cubic single crystals Zn 0.999Fe 0.001S 1 ? x Se x ( x = 0, 0.2) obtained by the chemical transport method has been investigated using thermal neutron diffraction for the first time. It has been found that the diffraction patterns of these crystals contain the previously unknown effects of diffuse scattering caused by local statistic atomic displacements in the metastable fcc lattice. 相似文献
10.
The structure of a Zn 1?x Cr xSe semiconductor crystal with x = 0.0029 was studied using thermal neutron diffraction. It was detected that the diffraction patterns of the crystal contain regions of diffuse scattering concentrated in the vicinity of the strong Bragg reflections. It was shown that the diffuse scattering was caused by transverse displacements of lattice atoms induced by chromium impurities, which undergo static tetragonal Jahn-Teller distortions in ZnSe. 相似文献
11.
From the concentration dependence of the widths and intensities of Raman lines and from the patterns of photoinduced light scattering, it is found that the mechanism of incorporation of Zn 2+ cations into the LiNbO 3 crystal structure changes with increasing concentration of zinc in the melt, which leads to an abrupt anisotropic expansion of oxygen octahedra along the polar axis. In this case, the number of kinks in the concentration dependence of linewidths (5) considerably exceeds the number of concentration threshold (2) known from the literature. It is shown that B 3+ ions almost do not enter the cationic sublattice of the LiNbO 3 crystal but changes the melt structure, so that the LiNbO 3:B crystal is characterized by a high structural and optical homogeneity and a low photorefractive effect. 相似文献
12.
The fine structure of a single crystal of the Zn 0.9Ni 0.1S cubic compound synthesized by the chemical transport method has been investigated at room temperature using thermal neutron diffraction. It has been found that the diffraction patterns of this compound, along with strong Bragg reflections of the facecentered cubic phase, include a system of diffuse maxima, which indicate the occurrence of a local deformation of the cubic structure by the Jahn-Teller nickel ions. Results of this experiment have been compared with the previously obtained data for the lightly doped Zn 1 ? x Ni x Se single crystal ( x = 0.002). 相似文献
13.
Neutron diffraction and magnetic measurements have been used to study the effect of doping with Mn 3+ ions on the fine crystal structure of the Ga 2Se 3 monoclinic compound. It has been established that the structural state of the crystals is changed even at a relatively low
doping level ( x = 0.04). Arguments in favor of the fact that local Jahn-Teller distortions are responsible for the formation of the fine
structure and magnetism in compounds of this class are presented. 相似文献
14.
The complexation reactions between murexide and Zn 2+, Cd 2+ and Pb 2+ ions in C 2H 5OH-H 2 mixtures have been investigated spectrophotometrically. Formation constants of the resulting 1:1 complexes were determined and found to vary in the order Pb 2+ > Cd 2+ > Zn 2+, in all binary ethanol-water mixtures used. There is an inverse relationship between the complex formation constants and amount of water in the mixed solvent. A linear relationship was observed between log K f for complexes and the mole fraction of ethanol. 相似文献
15.
Here, we present the effect of different Zn contents on the structural, morphological, and optical properties of CdXZn1-XS thin films deposited by electrodeposition method on stainless steel and indium-doped tin oxide (ITO) glass substrates. Electrosynthesized CdXZn1-XS thin films are characterized by using X-ray diffraction (XRD), UV-Vis spectrophotometer, field emission scanning electron microscope (FE-SEM), and surface wettability analysis. XRD pattern reveals that the CdXZn1-XS thin films are polycrystalline in nature with hexagonal crystal structure. FE-SEM micrograph displays that these CdXZn1-XS thin films exhibit the different sizes of sphere-like nanostructures by varying the X value. The optical absorption study indicates that drastic variation in band gap energy of CdXZn1-XS thin films. In advance photovoltaic measurements, CdXZn1-XS thin films are to be studied by forming the photoelectrochemical (PEC) cell having CdXZn1-XS/0.5 M (Na2SO3)/C configuration. The efficiency values of CdXZn1-XS are found to be 0.2, 0.35, 0.32, 0.25, and 0.23 % respectively at X content. 相似文献
16.
The hyperfine fields of Cu 2+ and F - ions nearest to a Zn 2+ ion are measured by a spin echo method in a single crystal of K 2Cu 0.95Zn 0.05F 4. It is shown that the local symmetry due to the Jahn-Teller distortion is practically unaffected by the proximity of Zn 2+ ions. 相似文献
17.
Single crystals of Zn xCd 1?xS have been grown from the vapour phase at 1100°C in the presence of H 2S gas. X-ray diffraction studies of the as-grown crystals show that polytypism and stscking faults occur in Zn xCd 1?xS crystals for x ? 0.94. It is observed that for 0.92 < x < 0.98 the 2H structure of Zn xCd 1?xS crystals transforms to a disordered 6H structure on annealing in vacuum around 600°C. For 0.95 < x < 0.98 this 6H structure finally transforms to a disordered 3C structure on annealing further at higher temperatures around 800°C. The structural transformations occur through a non-random insertion of stacking faults, as revealed by the diffuse streak joining the X-ray diffraction maxima along the 10. L reciprocal lattice row. Experimental investigation of the diffuse intensity distribution, as recorded on a single crystal diffractometer from partially transformed single crystals, reveals that the mechanism of the transformation is very different from that reported for the same transformation in silicon carbide and cannot be described in terms of a single-parameter model of non-random deformation faulting. 相似文献
18.
The character of structural and magnetic features of the cubic lattice of bulk Zn 1 ? x Cr x Se crystals (0 ≤ x ≤ 0.045) has been investigated using thermal neutron diffraction and magnetic measurements. It has been found that the diffraction scans of doped crystals contain effects of nuclear diffuse scattering caused by local static atomic displacements in the face-centered cubic (fcc) lattice. Results of magnetic measurements of doped crystals indicate the presence of weak antiferromagnetic correlations, which are a consequence of structural features of these compounds. 相似文献
19.
Firstly, the coordination processes of line-type polyethyleneimine with Cu 2+, Cd 2+ and Zn 2+ were studied by using visible light absorption spectroscopy and chelation conductivity titration method, and the structures of the chelates were determined. Afterwards, polyethyleneimine (PEI) was grafted onto the surface of silica gel particles via the coupling effect of γ-chloropropyl trimethoxysilane (CP), and the novel composite adsorption material PEI/SiO 2 with strong adsorption ability towards heavy-metal ions was prepared. The chelating adsorption properties of PEI/SiO 2 for Cu 2+, Cd 2+ and Zn 2+ were researched by both static (batch) and dynamic (flow) methods. The experiment results show that water-soluble polyamine PEI with line-type structure reacts with Cu 2+, Cd 2+ and Zn 2+ easily and quantitatively, and water-soluble chelates with four ligands are formed. The composite material PEI/SiO 2 possesses very strong chelating adsorption ability for heavy-metal ions, and the saturated adsorption amount can reach 25.94 mg g −1 and 50.01 mg g −1 for Cu 2+ under static and dynamic conditions, respectively. The isothermal adsorption data fit to Langmuir equation, and the adsorption is typical chemical adsorption with monomolecular layer. The adsorbing ability of PEI/SiO 2 towards the three kinds of the ions follows the order of Cu 2+ > Cd 2+ > Zn 2+. The pH value has great influence on the sorption, and at pH 6-7, the adsorption capacity is the greatest. The fact that adsorption capacity increases with temperature rising indicates the adsorbing process of PEI/SiO 2 for metal ions is endothermic. As diluted hydrochloric acid is used as eluent, the adsorbed heavy-metal ions are eluted easily from PEI/SiO 2, and the regeneration and reuse without decreasing sorption for PEI/SiO 2 are demonstrated. 相似文献
20.
The effect of the substitution of Co 2+, Mn 2+, and Zn 2+ ions for Ni 2+ ions on the magnetic, dielectric, and ferroelectric properties of vanadate single crystals (Ni 1 − x
T
x
) 3V 2O 8 has been analyzed. It has been found that the low-level ( x ≤ 0.1) substitution of both magnetic and nonmagnetic ions stabilizes the ferroelectric state with a cycloidal magnetic structure.
The existence region of this state is expanded to low temperatures down to 3 K for Zn 2+ and below 1.8 K for Co 2+ and Mn 2+ owing to the suppression of a low-temperature weak ferromagnetic phase. At the same time, the ferroelectric phase disappears
completely at large concentrations of Co and Mn. The effect of magnetic fields on the magnetic and ferroelectric states has
been analyzed. It has been shown that the magnetic field along the c axis suppresses the ferroelectric state, whereas the magnetization along the antiferromagnetism axis ( a axis) induces the reentrant phase transition from a paraelectric weak ferromagnetic structure to a ferroelectric structure.
The corresponding H-T phase diagrams have been drawn. 相似文献
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