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1.
E. Z. Valiev I. F. Berger V. I. Voronin V. A. Kazantsev 《Crystallography Reports》2011,56(7):1160-1164
The magnetic and lattice properties of a sample of La(Fe0.86Si0.14)13 ferromagnet have been measured. The influence that neutron irradiation has on the physical properties of this ferromagnet is studied. It is shown that the irradiation of this sample by a fluence of 3 × 1019 n/cm2 increases the lattice constant a and the Curie temperature (T C ) as the volume magnetostriction decreases. A model of ferromagnet is proposed which satisfactorily describes the dependence a(T) of the initial and irradiated samples and their magnetic properties. The temperature dependence of the change in entropy when switching the magnetic field on and off is calculated. It is established that the change in both the magnetic and lattice parts of the total entropy at the magnetic phase transition must be taken into account for La(Fe x Si1 ? x )13 compounds. 相似文献
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Crystallographic parameters of TlInS x Se2 ? x solid solutions have been measured by X-ray diffraction. Dependences of the unit-cell parameters on the composition are determined. It is established that the values of parameters a, b, and c and the angle β decrease with an increase in x. It is shown that the TlInS x Se2 ? x system includes a continuous series of solid solutions based on the TlInSe2 compound with tetragonal symmetry at x values ≤ 0.4, while at x ≥ 0.6 solid solutions based on the TlInS2 compound with a monoclinic structure are formed. 相似文献
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The kinetics of transformation behavior of roller-quenched amorphous Pd83Si17 and Pd80Si20 alloys after linear and isothermal heating is reported. The transformation was examined with electron microscopy, electron diffraction and electrical resistivity measurement. The crystallization of amorphous alloys with 17 at% Si begins with metastable ordered fcc solid solution. The ordered fcc solution is transformed to a ordered metastable phase with, probably, orthorhombic structure. The crystallization of amorphous alloys with 20 at% Si begins by formation of spherulites with lamellar structure. Using electron diffraction we found that spherulites consist of two phases - orthorhombic Pd3Si silicide and Pd-rich silicide. From resistivity measurements, activation energies of 28.5 kcal/mol for Pd83Si17 and 80 kcal/mol for Pd80Si20, respectively, were calculated. 相似文献
4.
The structure of the interfaces of a 10-nm-thick InxGa1 ? x As quantum well buried in the semiconductor GaAs matrix has been studied by the method of double-crystal X-ray diffractometry. It has been shown that, in comparison with the well-known photoluminescence method, the X-ray diffraction method has considerable advantages in characterization of multilayer systems. The detailed analysis of the rocking curves provided the reconstruction of the profiles of indium distributions in quantum wells for specimens with different indium concentrations. 相似文献
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The formation of glass in the GeSiS system was investigated. After synthesis of material with the general formula Ge1?xSixSy, where x was chosen to be 0.05, 0.1, 0.2, 0.3 and y was in the range 1.28–3.6, cylindrical samples were prepared and used for the characterization of glass by means of DTA. It was found that the substitution of germanium with silicon does not lead to any expressive change of the glass transition temperature, crystallization and the onset of melting. 相似文献
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In this work, we present a systematic study on the crystallization kinetics and the magnetic properties of melt-spun Fe80B10Si10 ? xGex (x = 0.0 ? 10.0) amorphous alloys. The activation energy for crystallization, determined by differential scanning calorimetry, displayed a strong dependence on the Ge content, reflecting a deleterious effect on the alloys' thermal stability and their glass forming ability with increasing Ge concentration. On the other hand, the alloys exhibited excellent soft magnetic properties, i.e., high saturation magnetization values (around 1.60 T), alongside Curie temperatures of up to 600 K. Complementary, for increasing Ge substitution, the ferromagnetic resonance spectra showed a microstructural evolution comprising at least two different magnetic phases corresponding to a majority amorphous matrix and to Fe(Si, Ge) nanocrystallites for x ≥ 7.5. 相似文献
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Crystallography Reports - Ga x In1 ? x Sb solid solution single crystals (x = 0.03–0.09) have been grown. The dislocation density and electrophysical parameters are measured. A... 相似文献
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The effect of rare-earth elements on the plasma etching behavior of oxide glasses were investigated to develop the window glass for a plasma processing chamber in the semiconductor industry. Aluminosilicate glasses with various rare-earth elements (Y, Gd and La) were prepared and their optical transmittance and plasma etching depth were evaluated. The plasma etching behavior of the glasses was estimated by X-ray photoelectron spectroscopy analysis at the fluorine plasma exposure surface of the glasses. The rare-earth element in the glass was highly related to various properties such as density, molar volume, mechanical properties and plasma etching depth. The cationic field strength of the rare-earth element more strongly affected the plasma etching depth of the glasses than the sublimation point of the fluorine compounds and this may be related to the plasma etching condition. 相似文献
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P. P. Fedorov V. B. Aleksandrov O. S. Bondareva I. I. Buchinskaya M. D. Val'kovskii B. P. Sobolev 《Crystallography Reports》2001,46(2):239-245
Unit-cell parameter a of the cubic phases with a varying composition Na0.5 ? x R 0.5 + x F2 + 2x (R = Gd-Lu and Y) and with a fluorite-type structure, is described within an accuracy of ±0.003 Å, by the formula a = 4.454 + 0.874r 3 + x(6.7238r 3 ? 7.259) where r 3 is the Shannon “crystal ionic radius” R 3+ at c.n. = 8. 相似文献
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V. I. Maksimov S. F. Dubinin T. P. Surkova V. D. Parkhomenko 《Crystallography Reports》2013,58(3):468-473
The structure of cubic Zn0.999Fe0.001S x Se1 ? x (0 ≤ x ≤ 1) crystals obtained by vapor-phase chemical transport has been investigated by thermal-neutron diffraction. The diffraction patterns of these crystals are found to exhibit previously unknown diffuse-scattering effects related to local static atomic displacements in the metastable fcc lattice. It is substantiated that the tendency to form polytypes, which is characteristic to a greater extent of zinc sulfide, can be a key factor of instability in the lattice of compounds belonging to the series of anion-substituted solid solutions under study. 相似文献
15.
E. V. Dmitricheva I. P. Makarova V. V. Grebenev V. V. Dolbinina I. A. Verin R. Chitra R. R. Choudhury 《Crystallography Reports》2014,59(6):878-884
The influence of isomorphous replacement in the cation sublattice on the kinetics of the phase transition in single crystals of the solid solutions (K x (NH4)1 ? x ) m H n (SO4)(m + n)/2 · yH2O belonging to the K3H(SO4)2-(NH4)3H(SO4)2-H2O salt system was studied. Superproton phase transitions for the end compositions of this system have been found earlier. The optical and thermal properties of crystals with the composition (K,NH4)3H(SO4)2 in the temperature range from 295 to 500 K were investigated, and the crystal structure was determined at 295 K. The results of the study and the comparison with the literature data show that the replacement of potassium atoms with ammonia leads to a fundamental change in the kinetics of the phase transition, the phase-transition temperature remaining virtually unchanged. 相似文献
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The relationship between the superionic transport in fluorite phases M 1 ? x R x F2 + x (M = Ca, Sr, or Ba; R are rare earth elements) and their defect structure has been analyzed. The superionic conductivity of M 1 ? x R x F2 + x crystals is provided by the high concentration of charge carriers. However, the carrier concentration is several tens of times lower than the concentration of anionic defects, which is explained by the presence of defect regions (DRs), which partially block carriers. The dependence of the superionic conductivity of M 1 ? x R x F2 + x phases on the RF3(x) content has a percolation nature. Crystals of these phases are divided into two groups with respect to the percolation threshold: x p, 1 = 2–3 mol % RF3 and x p, 2 = 7–8 mol % RF3. The corresponding DR volumes are 3000–4000 Å3 (x p, 1) and 500–700 Å3 (x p, 2). The x p, 1, and x p, 2 values correlate, respectively, with the octahedral cubic {M 14 ? p R p F68 ? 69} and tetrahedral {M 4 ? p R p F26} clusters, which are DR cores. The DR model and cluster structure are indicative of the heterogeneity of nonstoichiometric M 1 ? x R x F2 + x crystals at the nanoscale level with respect to the chemical composition and the electrical and crystallochemical (coordinations of M and R) characteristics. 相似文献
18.
N. I. Sorokin 《Crystallography Reports》2000,45(5):799-803
A crystallochemical model of ion-transport percolation in M 1?x RxF2+x (M = Ca, Sr, Ba; R = RE) solid solutions with the “defect” CaF2-type structure has been suggested. Within this model, the percolation thresholds in M 1?x RxF2+x crystals with tetrahedral R 4F26? and octahedral R 6F37? clusters are considered, whose existence is highly probable in these disordered fluorite phases. It is established that the calculated percolation thresholds x c = 2.8 mol % for nnn (next nearest neighbors) [(R 6F37) M6F32 ?Fi] and x c = 4.7 mol % for nn (nearest neighbor) [(R 4F26) M6F32 ?Fi] are in satisfactory accord with the experimental percolation thresholds determined from the conductometric data. 相似文献
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A. M. Golubev L. P. Otroshchenko V. N. Molchanov B. P. Sobolev 《Crystallography Reports》2008,53(6):966-973
The displacements of Ba2+ cations in the cationic motif of Ba0.78Tm0.22F2.22 crystals, which are representatives of nonstoichiometric fluorite phases Ba1 ? x R x F2 + x , are proved for the first time with the use of precision investigations of the fine atomic structure. It is shown that the cation displacements, like the previously revealed displacements in the anionic motif, reflect the formation of {Ba8[R 6F68–69]} superclusters of structural defects with nanometer linear sizes. The Ba 2+ cations are displaced from the fluorite crystallographic positions 4a (space group Fm $ \bar 3 The displacements of Ba2+ cations in the cationic motif of Ba0.78Tm0.22F2.22 crystals, which are representatives of nonstoichiometric fluorite phases Ba1 − x
R
x
F2 + x
, are proved for the first time with the use of precision investigations of the fine atomic structure. It is shown that the
cation displacements, like the previously revealed displacements in the anionic motif, reflect the formation of {Ba8[R
6F68–69]} superclusters of structural defects with nanometer linear sizes. The Ba 2+ cations are displaced from the fluorite crystallographic positions 4a (space group Fm
m) to the positions 32f. The static nature of the cation displacements is confirmed by the fact that these displacements are retained at a temperature
of 110 K. The correctness of the interpretation of the correlation between the cation displacements and the formation of superclusters
of structural defects is supported by the coincidence of the intercationic distances determined in the disordered phase Ba0.78Tm0.22F2.22 with those found in the previously studied ordered phases Ba4
R
3F17 (R = Y, Yb). The model with splitting of cationic positions is appropriate for testing in structural investigations of crystals
of the fluorite phases M
1 − x
R
x
F2 + x
at room temperature.
Original Russian Text ? A.M. Golubev, L.P. Otroshchenko, V.N. Molchanov, B.P. Sobolev, 2008, published in Kristallografiya,
2008, Vol. 53, No. 6, pp. 1023–1030. 相似文献