Kinetics of phase separation and ordering in alloys

Vaks, V. G.

doi:10.1016/j.physrep.2003.10.005

Cited by 42 publications

(72 citation statements)

References 35 publications

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“…The most compelling origin of this inhomogeneity is the non-uniform distribution of oxygen atoms in those non-stoichiometric materials. However, the inhomogeneity may be traced to other causes of the nanoscale phase separation observed not only in superconducting and magnetic oxides [33][34][35][36][37]118,119] but also in other magnets [120,121], non-equilibrium alloys [122], porous systems [123,124], and colloids [125,126]. In the case of STM spectroscopy, the tunnel current is apparently harvested from a small area of the atomic size on the substrate [127].…”

Section: Account Of Inhomogeneitymentioning

confidence: 99%

Spatial distribution of superconducting and charge-density-wave order parameters in cuprates and its influence on the quasiparticle tunnel current (Review Article)

Gabovich

Войтенко

2016

Low Temperature Physics

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The state of the art concerning tunnel measurements of energy gaps in cuprate oxides has been analyzed. A detailed review of the relevant literature is made, and original results calculated for the quasiparticle tunnel current J(V) between a metallic tip and a disordered d-wave superconductor partially gapped by charge density waves (CDWs) are reported, because it is this model of high-temperature superconductors that becomes popular owing to recent experiments in which CDWs were observed directly. The current was calculated suggesting the scatter of both the superconducting and CDW order parameters due to the samples' intrinsic inhomogeneity. It was shown that peculiarities in the current-voltage characteristics inherent to the case of homogeneous superconducting material are severely smeared, and the CDW-related features transform into experimentally observed peak-dip-hump structures. Theoretical results were used to fit data measured for YBa 2 Cu 3 O 7-δ and Bi 2 Sr 2 CaCu 2 O 8+δ . The fitting demonstrated a good qualitative agreement between the experiment and model calculations. The analysis of the energy gaps in high-T c superconductors is important both per se and as a tool to uncover the nature of superconductivity in cuprates not elucidated so far despite of much theoretical effort and experimental progress. PACS

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Section: Account Of Inhomogeneitymentioning

confidence: 99%

Spatial distribution of superconducting and charge-density-wave order parameters in cuprates and its influence on the quasiparticle tunnel current (Review Article)

Gabovich

Войтенко

2016

Low Temperature Physics

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“…Replacement of a homogeneous precursor by a vermicular or lamellar intergrowth of product phases has long been recognised in materials- (Vaks 2004) and polymer science (Oswald et al 1987). The underlying process is referred to as cellular segregation reaction (Cahn 1959;Christian 2002).…”

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confidence: 99%

Synthesis of monticellite–forsterite and merwinite–forsterite symplectites in the CaO–MgO–SiO2 model system: influence of temperature and water content on microstructure evolution

Remmert

Heinrich

Wunder

et al. 2017

Contrib Mineral Petrol

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Homogeneous single crystals of synthetic monticellite with the composition Ca 0.88 Mg 1.12 SiO 4 (Mtc I) were annealed in a piston-cylinder apparatus at temperatures between 1000 and 1200• C , pressures of 1.0-1.4 GPa, for run durations from 10 min to 24 h and applying bulk water contents ranging from 0.0 to 0.5 wt% of the total charge. At these conditions, Mtc I breaks down to a fine-grained, symplectic intergrowth. Thereby, two types of symplectites are produced: a first symplectite type (Sy I) is represented by an aggregate of rod-shaped forsterite immersed in a matrix of monticellite with end-member composition (Mtc II), and a second symplectite type (Sy II) takes the form of a lamellar merwinite-forsterite intergrowth. Both symplectites may form simultaneously, where the formation of Sy I is favoured by the presence of water. Sy I is metastable with respect to Sy II and is successively replaced by the latter. For both symplectite types, the characteristic spacing of the symplectite phases is independent of run duration and is only weeakly influenced by the water content, but it is strongly temperature dependent. It varies from about 400 nm at 1000• C to 1200 nm at 1100• C in Sy I, and from 300 nm at 1000 • C to 700 nm at 1200• C in Sy II. A thermodynamic analysis reveals that the temperature dependence of the characteristic spacing of the symplectite phases is due to a relatively high activation energy for chemical segregation by diffusion within the reaction front as compared to the activation energy for interface reactions at the reaction front. The temperature dependence of the characteristic lamellar spacing and the temperature-time dependence of overall reaction progress have potential for applications in geo-thermometry and geo-speedometry.

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“…System (16), (17) allows a partial equilibrium at . t AE • This solution is interpreted as the coexistence of two semiinfinite domains differing by sign of the order parameter [14,15]. Corresponding concentration profiles of the components have the typical "soliton" form [15].…”

Section: Asymptotical and Numerical Analysis Of Kinetic Equationsmentioning

confidence: 98%

“…Qualitative considerations about the role of the stoichiometry in formation of the equilibrium segregations were discussed in Refs. [15][16][17]. However they are not quite exhaustive.…”

Section: Asymptotical and Numerical Analysis Of Kinetic Equationsmentioning

confidence: 99%

Kinetics of coupled ordering and segregation in antiphase domains

Gumennyk¹,

Stefanovich²,

Feldman³

2008

Physica Status Solidi (b)

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We study a multi‐domain ordering kinetics in solid solutions under simultaneous diffusion of solute atoms. By the example of a binary bcc alloy a system of kinetic equations is derived, describing the coupled relaxation of occupancies of the two sublattices, building a bcc lattice, by A and B atomic species. Such an approach supplemented by the simplest mean‐field approximation proves sufficient to describe both the establishing of long‐range order and the segregation processes occurring in antiphase domains. An interaction and interrelation between evolution of the conserved and non‐conserved order parameter fields are elucidated. Asymptotical and numerical analysis of the obtained evolution equations reveals a multi‐stage scenario of the alloy relaxation: first comes the quick development of long‐range order which is then followed by the slow redistribution of local alloy concentration, so that the majority atoms segregate towards the region of an antiphase boundary. The alloy exhibits a distinct tendency to form a multi‐domain structure out of a solitary long‐range order parameter fluctuation of a certain sign. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Kinetics of phase separation and ordering in alloys

Cited by 42 publications

References 35 publications

Spatial distribution of superconducting and charge-density-wave order parameters in cuprates and its influence on the quasiparticle tunnel current (Review Article)

Spatial distribution of superconducting and charge-density-wave order parameters in cuprates and its influence on the quasiparticle tunnel current (Review Article)

Synthesis of monticellite–forsterite and merwinite–forsterite symplectites in the CaO–MgO–SiO2 model system: influence of temperature and water content on microstructure evolution

Kinetics of coupled ordering and segregation in antiphase domains

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