This 2003 book covers the fundamentals of conventional transmission electron microscopy (CTEM) as applied to crystalline solids. Emphasis is on the experimental and computational methods used to quantify and analyze CTEM observations. A supplementary website containing interactive modules and free Fortran source code accompanies the text. The book starts with the basics of crystallography and quantum mechanics providing a sound mathematical footing for the rest of the text. The next section deals with the microscope itself, describing the various components in terms of the underlying theory. The second half of the book focuses on the dynamical theory of electron scattering in solids including its applications to perfect and defective crystals, electron diffraction and phase contrast techniques. Based on a lecture course given by the author in the Department of Materials Science and Engineering at Carnegie Mellon University, the book is ideal for graduate students as well as researchers new to the field.
The field of materials science and engineering is on the cusp of a digital data revolution. After reviewing the nature of data science and Big Data, we discuss the features of materials data that distinguish them from data in other fields. We introduce the concept of process-structure-property (PSP) linkages and illustrate how the determination of PSPs is one of the main objectives of materials data science. Then we review a
Microstructure of α-GaN films grown by organometallic vapor phase epitaxy on sapphire substrates using low temperature AlN (or GaN) buffer layers has been studied by transmission electron microscopy. The defects which penetrate the GaN films are predominantly perfect edge dislocations with Burgers vectors of the 1/3〈112̄0〉 type, lying along the [0001] growth direction. The main sources of threading dislocations are the low angle grain boundaries, formed during coalescence of islands at the initial stages of GaN growth. The grain sizes range from 50 to 500 nm, with in-plane misorientations of less than 3°. The nature of these threading dislocations suggests that the defect density would not likely decrease appreciably at increasing film thickness, and the suppression of these dislocations could be more difficult.
The magnetometric (volume averaged) demagnetization factors for cylinders with elliptical cross section are computed using a Fourier-space approach and compared with similar results obtained with a different treatment. The demagnetization factors are given as a series expansion in the eccentricity ϵ of the elliptical cross section, where the terms up to order ϵ10 are given explicitly as a function of the cylinder aspect ratio. Other simplified expressions, valid in restricted regimes, are also given. Two different series expansions, obtained previously and valid in particular combinations of shape parameters, are recalled and compared with the new results. After the computation of the magnetostatic and exchange-energy terms associated with a vortex closure-domain state in the elliptic cylinder, the single-domain limit, or the critical size below which the structure can support quasi-uniform magnetization, is derived and discussed.
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