Change in primary extinction during decomposition of supersaturated solid solution

The integrated intensity of the matrix reflection (200) was measured during the precipitation of the, and phases. The observed effects were explained as the consequence of lattice defects formed in the neighbourhood of precipitate particles.

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(200) , . .

     

Change in primary extinction during decomposition of supersaturated solid solution II. Al-Cu 4% alloy-formation of G.P. zones

The change in integrated intensity of the (200) reflections of a solid solution during the formation of G.P. zones was measured and compared with the change in the character of the diffuse streaks corresponding to them. It was found that the. formation of G.P. zones does not lead to a decrease in primary extinction despite the great changes in the distribution of the copper atoms. It was shown that the formation of a precipitate accompanied by the formation of crystallographically incoherent boundaries greatly decreases the primary extinction.

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. II. 1-u 4%: [. . ]

(200) . . , . , . . , . , , , .

     

Change in primary extinction of X-rays in solid solution of NaCl-CdCl2

The Suzuki model of regions with a hyperstructure was verified, the dependence of their size on the cooling rate was found and it was determined that they disappear at temperatures between 250° and 300°C according to their composition. Up to 1000 Å their structure is coherent with a matrix lattice and their formation is not accompanied by a decrease in the primary extinction. Regions above 1000 Å are partially incoherent and their formation and disappearance are apparent by a change in the primary extinction.

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NaCl-CdCl₂

, , , 250°–300°C . , 1000 Å, . , 1000 Å, .

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The author would like to thank I. Kunzlová, and M. Lébl for preparing the crystals of NaCl-CdCl₂ solid solution and Dr. Trnka for determining the cadmium Concentration in them.     

Thermodynamic analysis of the decomposition of a supersaturated solid solution of the Fe-Cu system

The structure of Fe-5.5% Cu alloy is studied after eutectoid reaction and aging of the martensite. The thermodynamic analysis of decomposition of the supersaturated solid solution with copper release is peformed for different types of crystal lattice. The free energy of solid solutions and phase separation diagrams of the BCC and FCC phases of copper is calculated. Barriers for the nucleation of copper particles with BCC and FCC lattices are evaluated. The factors that favor the appearance of intermediate structural forms of copper preceding the formation of stable FCC phase are discussed.     

Structural state of Cu-Be-Ag alloys in the process of decomposition of solid solution

Investigation of aging Cu-1.5% Be-2% Ag and Cu-1% Be-4% Ag alloys was carried out in this study by the methods of x-ray analysis of monocrystals, and electron microscopy. In the aging process at 218, 300, and 450C, laminar zones of Guinier-Preston, enriched with beryllium and silver atoms were formed. Entry of silver into the zones widens the upper temperature interval of the zone stage to 450C. With the increase of annealing time the metastable-phase was precipitated. The crystals of -phase are precipitated with orientation in the direction (100) in consequence of interactions of the fields of elastic stresses occurring around -precipitations, and periodic structure is formed in the alloy. The stable phase-CuBe and Ag was precipitated in the Cu-1% Be-4% Ag-alloy.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 21–25, August, 1972.     

Electric and thermoelectric effects in a solid solution of ZnxCd1−xSb

The electrical conductivity, the Hall effect and the thermoelectric power were studied in thec andb crystallographic directions on single crystals of a solid solution of Zn_xCd_1–xSb for x= =0.2 as a function of the concentration of acceptors and the temperature. The observed anisotropy of the electrical conductivity and hole mobility in weakly and strongly doped solid solution is explained on the basis of the anisotropy of the effective mass of holes and the assumption of isotropic relaxation time.The authors thank V. Mísková, J. Beránková and J. Kaspar for preparing the materials and M. Neuvirtová and J. Mrnávková for help in the experimental work.     

The mechanism of decomposition of secondary nitramines in solution

It was found that, like hexogen, octogen, ketohexogen, and Tetryl decomposed in easily oxidizable solvents by the chain mechanism, whereas the decomposition of dimethylnitramine and framework nitramine CL-20 was a monomolecular reaction in solution.     

Component distribution of the solid solution AlxGa1-xAs during zone melting with a temperature gradient of the powderlike source

The component distribution of the ternary solid solution in epitaxial layers of Al_xGa_1-xAs grown by a zone recrystallization method by a temperature gradient during continuous feed maintenance by a powdery source consisting of a mixture of gallium arsenide and aluminum is analyzed theoretically. The possibility is shown of stationary growth of a material of constant composition as well as of epitaxial layers with controllable growing or decreasing aluminum arsenide distributions in the growth direction.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 52–55, February, 1987.In conclusion, the authors are grateful to V. N. Lozovskii for interest in the research and useful discussions.     

Nonisothermal nucleation in a solid solution of CuCl in glass: Concentration effect upon heating of the solid solution

Physics of the Solid State - The influence of the heating rate of a solid solution of CuCl in glass on the size distribution of the produced CuCl nanoparticles is studied. The distribution curves...     

Study of ammonia decomposition in a proton conducting solid electrolyte cell

The reaction of NH₃ decomposition was studied at 500–700 °C and atmospheric total pressure using a single-chamber cell-reactor. The proton conductor was a strontia-ceria-ytterbia (SCY) perovskite of the form: SrCe_0.95Yb_0.05O_3−α. Silver films served as cathodic and anodic electrodes. The effects of imposed current, temperature and inlet gas composition on the reaction rate were examined. Paper presented at the 8th EuroConference on Ionics, Carvoeire, Algarve, Portugal, Sept. 16–22, 2001.     

Bounded diffusion in solid solution electrode powder compacts. Part I. The interfacial impedance of a solid solution electrode (MxSSE) in contact with a m+-ion conducting electrolyte

The transient and ac electrical response of electrochemical systems containing a solid solution electrode is derived using Laplace transform methods. First, the operational impedance of the electrolyte/solid solution electrode interface is derived, for both asymmetrical and symmetrical cell systems. From the operational impedance the current, voltage and ac impedance response is calculated. By combination of semi-infinite and bounded diffusive behaviour, both the chemical diffusion coefficient of the inserted ions and the thermodynamic factor (? ln a/? ln c) can be obtained from kinetic data only.     

Short range order in a solid solution Ni-8 at. % Nb

Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 28–30, December, 1990.     

Study of specific features of decomposition of iron solid solution in commercial beryllium by M?ssbauer spectroscopy

This work studies the precipitation of secondary phases in beryllium at 600, 560, and 500°C. Cast and hot-pressed beryllium alloys with iron content of 0.09°-0.8 wt % were studied. M?ssbauer spectra of samples annealed over a total of more than 500 h were obtained. Precipitation processes were studied on the basis of diffusion models.     

Secondary radiation of the semiconducting solid solution Zn x Cd1−x S during selective excitation

We present the results of spectroscopic studies of secondary radiation of the solid solution Zn_xCd_1–xS (0.05相似文献   

Atom distributions in mixed interstitial-substitutional solid solution: The case of Fe1−xNixNy austenite

Mössbauer Spectra of Fe_1-xNi_xN_y austenite with 0相似文献   

Radiation-induced phase transition in a film of niobium-tin solid solution

A 5-μm-thick film of a niobium-tin solid solution (18.3 at % Sn) grown by ion-plasma sputtering with subsequent codeposition of ultrafine metal particles is irradiated by a fast proton flux with a fluence of 10¹⁹ p ⁺/cm². X-ray diffraction analysis carried out using CuK _α (λ = 0.154178 nm), CoK _α (λ = 0.179021 nm), and MoK _α (λ = 0.071069 nm) radiations shows the presence of a radiation-induced stannide niobium (Nb₃Sn) phase in the region of proton energy dissipation (at a depth of 2.5 μm from the surface of the solid solution film). It is found that at the end of the particle range, nonlocal interaction between the protons and the concentrated matrix solid solution takes place. When interacting with the supersaturated solid solution, a bombarding particle covers a tangible area of the solution, so that an intermetallic phase greater than critical in size nucleates. The feasibility is demonstrated of using a fast particle flux to produce an intermetallic (superconducting) phase inside a solid solution layer with a composition close to the stoichiometric composition of the intermetallic.     

Production and decay of subcritical nuclei in a solid solution

The decay of “subcritical” nuclei in a solid solution has been revealed in the investigation of the CuCl phase nucleation kinetics in glass. As soon as “supercritical” nuclei with an average radius R = 1.1 nm are created at 500°C, a sharp temperature increase up to 650°C transforms most nuclei created in the first annealing stage into “subcritical” ones, and this results in the decay of 80% of the nuclei in 5 min, while the remaining 20% of the nuclei grow in size to 2.4 nm. Their growth provides a sixfold increase in the CuCl phase growth rate against that in conventional annealing at 650°C. The kinetic dependences of the nucleation parameters—the amount of the phase and the average radius and concentration of the particles—were determined by the intrinsic absorption spectra of the CuCl nanocrystals. The critical radius of the CuCl nanomelt at 650°C has been estimated as 1.3 nm and the evaporation heat of the CuCl phase molecules in glass, as 13 kJ/mol. It is shown that multistage annealing makes it possible not only to control the parameters of the particles of the new phase, but also to determine the critical parameters of the initial nucleation stage.     

Morphology of the stabilized natural faces of a CdS1−x Sex solid solution

The morphology of the stabilized surfaces of CdS_1?x Se_x crystals exposed to air at room temperature is studied by atomic force microscopy. The characteristic features of the relief of the natural faces of these crystals are described, and the causes of the appearance of these features are discussed. The morphological results are related to the results of the microcathodoluminescence study of surface micro-and nanostructures. This study revealed objects that contribute to exciton emission and, hence, are CdS_1?x Se_x solid solutions.