Scanning X-ray Apparatus for Crystal Texture Mapping and Micro-Fluorescence Analysis

Extract

Scanning x-ray mapping based on energy dispersive x-ray diffraction is a powerful technique for imaging the spatial distributions of crystal texture and elements [1, 2]. Odd-shaped samples can be studied in air at ambient pressure and without special preparation. A schematic drawing of the scanning x-ray apparatus is shown in Figure 1. A “white” radiation x-ray source (PHILIPS generator PW 1830/25 equipped with a fine-focus tungsten tube) rather than characteristic radiation is used. The high density target material gives rise to an intense continuous Bremsstrahlung background. A collimator, consisting of two circular pinhole diaphragms, is attached to the tube and produces an aperture of 0.3° and an effective beam diameter of 50 μm on the sample. The apertures, Δθ, of the primary and secondary beams are not critical, since crystal texture is scarcely sharper than several degrees, and x-ray fluorescence lines are not affected at all by the aperture settings.