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The temporal evolution of microstructural features in metals and ceramics has been the subject of intense investigation over many years because deviations from normal grain growth behavior are ubiquitous and strongly dictate observed mechanical and magnetic properties. To distinguish among different grain growth scenarios, we examine the time evolution of the information content of both synthetic and experimental coarsening microstructures as quantified by both a computable information density (CID) and a spectral entropy along with selected metrics and measures of shared information and interaction strength. In these approaches, microstructural evolution is described in terms of two time series representations, namely: (1) strings and their compressed counterparts that reflect the information contained in the configuration of a system over time, and (2) the spectra of graph Laplacians that embody the information contained in a coarsening grain network. These approaches permit one to characterize dynamically evolving microstructures and to identify correlation times associated with different coarsening scenarios. Moreover, as the information content of a system is a proxy for the entropy, a thermodynamic description of grain growth is also described. [ABSTRACT FROM AUTHOR]

Thin film CoPt/Co bilayers have been prepared as a model system to investigate the relationship between microstructure and exchange coupling in two-phase nanocomposite permanent magnets. The bilayers were prepared by magnetron sputter deposition of near-equiatomic CoPt with a thickness of 25 nm onto oxidized Si wafers. In the as-deposited state, CoPt had the A1 (fcc) structure and was magnetically soft. Before reinsertion into the sputtering chamber for the deposition of 2.8–16.7 nm thick Co layers, the CoPt films were annealed at 700 °C for 120 min to produce the magnetically hard, fully ordered L1[sub 0] phase. The presence of exchange coupling in the bilayers was verified by magnetic hysteresis and recoil measurements and showed that only for Co thicknesses below 6.3 nm was this layer (in its as-deposited state) coupled through its full thickness to the CoPt layer. Annealing the bilayer samples at 300 and 550 °C for 20 min resulted in improvement of the interlayer magnetic coupling and produced clear differences in the magnetic reversal coherency and the recoil curves. However, for some samples, the improved coupling resulted in a decrease in coercivity, indicating that there is an optimum in the coupling strength for the attainment of high coercivity. Transmission electron microscopy studies of the bilayers in plan view showed that the increased interlayer coupling with annealing was a result of improved granular epitaxy of Co to CoPt. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We model electrodeposition using a formalism developed to describe nucleation and growth processes. In particular, we calculate non-equilibrium, equal-time correlation functions that capture the kinetics of electrodeposition (with particular application to elemental metals) and highlight the evolving correlation lengths and associated roughness in a growing electrodeposited film. These results are interpreted for the case of diffusion-limited growth at late times and, via a phase-field model, for the case of interface-controlled growth. Finally, we discuss the analysis of experimental deposition data using the formalism outlined here and demonstrate that important kinetic information may be readily extracted. [ABSTRACT FROM AUTHOR]

In this work, a recently developed electron diffraction technique called diffraction scanning transmission electron microscopy (D-STEM) is coupled with precession electron microscopy to obtain quantitative local texture information in damascene copper interconnects (1.8 μm-70 nm in width) with a spatial resolution of less than 5 nm. Misorientation and trace analysis is performed to investigate the grain boundary distribution in these lines. The results reveal strong variations in texture and grain boundary distribution of the copper lines upon downscaling. Lines of width 1.8 m exhibit a strong h111i normal texture and comprise large micron-size grains. Upon downscaling to 180 nm, a f111gh110i bi-axial texture has been observed. In contrast, narrower lines of widths 120 and 70 nm reveal sidewall growth of f111g grains and a dominant h110i normal texture. The microstructure in these lines comprises clusters of small grains separated by high angle boundaries in the vicinity of large grains. The fraction of coherent twin boundaries also reduces with decreasing line width. [ABSTRACT FROM AUTHOR]

The microstructure and the electronic work function of Pt–Ru alloy thin films spanning the compositional range from pure Pt to pure Ru were investigated. Nominally 50 nm thick films were cosputtered from elemental targets in an ultrahigh vacuum chamber. X-ray reflectivity and Rutherford backscattering spectroscopy were used to determine the film thicknesses and compositions. The electronic work function of the alloy film samples was determined by analysis of the capacitance-voltage characteristics of films deposited as part of a metal-oxide-semiconductor capacitor structure and found to range from 4.8 eV for pure Ru to 5.2 eV for pure Pt. To better understand the variation in work function for the intermediate compositions, the films were characterized by transmission electron microscopy and x-ray and electron diffractions. A notable increase in the compositional range of the hexagonal close packed (hcp) phase was observed, suggesting a metastable extension of the hcp phase stability as compared to bulk Pt–Ru alloys. The steepest change in the electronic work function for the intermediate alloy compositions coincided with a rapid change in the c/a ratio of the hcp phase. [ABSTRACT FROM AUTHOR]

The impact of short-range repulsive interactions between nuclei on the evolution of a phase transformation is studied in order to describe quantitatively the kinetics of the transformation and to characterize systematically the resulting microstructures. For these purposes both computer simulation and analytical methods are employed in order to investigate an idealized, two-dimensional model of nucleation and growth wherein nuclei contained in a background phase (e.g., liquid) interact via a "hard-core" repulsion, a prototype for systems with a variety of possible interactions. Several quantities, including the dynamic area and perimeter fractions as well as the distribution of coalesced grain areas, are calculated. It is found, for example, that the temporal evolution of the system differs markedly from that in which the nuclei are spatially uncorrelated, particularly as the core diameter becomes large relative to the characteristic internuclear separation for noninteracting nuclei, and an approximate, analytic description of this behavior is obtained. Finally, the morphologies of the grains constituting the transformed microstructures are linked with the range of the internuclear interaction. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]