![]() In this chapter, we introduce the various aspects of QTA and describe the additional information that CA can yield for the full characterization of real materials. It then becomes crucial to quantitatively take the textured character of the measured samples into account, either independently of other parameters that are accessible to diffraction (phase content, stresses, particle sizes and shapes), as in quantitative texture analysis (QTA), or to take these parameters into account by refining them all together, as in the combined-analysis (CA) methodology. Very often this grinding is not acceptable, as in the case of rare samples (for example fossils or comets), when grinding modifies the physical properties of the samples themselves (residually stressed materials), or when grinding is simply not possible (thin films). Rietveld analysis Rietveld, 1969 ) are not appropriate or require sample grinding. Unfortunately, when samples are crystallographically oriented to benefit from the intrinsic anisotropic properties of the constituent crystals, many characterization techniques ( i.e. Such `real samples' are obtained by complex techniques (alignment under uniaxial pressure, magnetic or electric fields, thermal gradients, flux or substrate growth, and combinations of these), and sample preparation is often difficult and time consuming. Consequently, any nondestructive characterization technique (for example diffraction) faces the difficulty of analysing textured samples, which are in a state between a perfect single crystal and a perfect powder. On the other hand, a perfectly randomly oriented powder is often impossible to obtain, or may even be undesirable if the anisotropic character of the sample is to be maintained. An example illustrates the efficiency of CA for characterizing a complex sample made of three thin textured and stressed layers.įor many solids, the growth of single crystals with sufficiently perfect crystallinity is not easy to manage, and is sometimes impossible. Experimental requirements, instrumental contributions and implementations of texture, line broadening, layering, residual stresses etc. Generalized Rietveld refinement is introduced to physically account for texture presence (as opposed to other texture-correction models, like the March–Dollase model) combined analysis is core to this, and all the various sample characteristics seen by scattering of X-rays are accounted for. Magnetic QTA is described, using magnetic pole figures and magnetic ODs, characterizing the macroscopic magnetic polarization of the sample. The link between reciprocal-space maps and crystallite orientations is explained. Pole figures and OD types are related to the degrees of freedom for the crystallites to orient in the sample. Methods for resolving the OD (generalized spherical harmonics, vector, WIMV–EWIMV, entropy maximization, components, exponential harmonics, arbitrary defined cells, Radon transform), inverse pole figures, and estimators for OD refinement quality and texture strength are described. The orientation distribution (OD) of the crystallites is defined, and various ways to resolve the QTA fundamental equation are detailed, including pole-figure measurements and normalization. QTA is frequently used because the existence of texture determines the characteristics and properties of the sample. Various aspects of crystallographic quantitative texture analysis (QTA) are introduced and the additional information that combined analysis (CA) can yield for the full characterization of real materials (textured, stressed, nanosized, layered etc.) is described.
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