Conventional and Synchrotron X-Ray Topography of Defects in the Core Region of SrLaGaO₄

Abstract

SrLaGaO 4 single crystals are perspective substrate materials for high temperature superconductors thin films, elements of thermal radiation receivers and other electronic devices. The defect structure of the Czochralski grown SrLaGaO 4 crystal was investigated by means of X-ray topography exploring both conventional and synchrotron sources. The crystal lattice defects in the core region of the crystal were investigated. The regular network of defects arranged in rows only in 100 direction was observed. Owing to high resolution of synchrotron radiation white beam back reflection topographs one can distinguish individual spots forming the lines of the rows. It can be supposed that these elongated rod-like volume defects are located in {100} lattice planes forming a kind of walls. They are built approximately of the same phase as crystal but crystallize at a different moment than a rest of the crystal due to the constitutional supercooling.

Contrast in transmission X-ray diffraction topographs of growth defects in the core of SrLaGaO4single crystals

“…The earlier studies performed by means of white-and monochromatic beam back-reflection synchrotron radiation topography show (owing to their high resolution) fine details of the single linear contrast in the form of individual dots (Malinowska, Lefeld-Sosnowska, Wieteska et al, 2006a,b;Malinowska et al, 2008Malinowska et al, , 2009. The features of the dot-like contrasts are similar to simulated monochromatic beam backreflection images of shrinking rod-like inclusions (Wierzchowski et al, 2010).…”

“…The features of the dot-like contrasts are similar to simulated monochromatic beam backreflection images of shrinking rod-like inclusions (Wierzchowski et al, 2010). Rows of individual defects, associated with dot-like contrasts arranged in lines, appear also in optical micrographs (Malinowska, Lefeld-Sosnowska, Wieteska et al, 2006a,b;Malinowska et al, 2008Malinowska et al, , 2009 (Fig. 4b).…”

“…In previous studies a characteristic network of linear diffraction contrasts, arranged in rows along the h100i and h110i directions, was detected on X-ray topographs of the core region of SLG crystals (Malinowska, Lefeld-Sosnowska, Pają czkowska & Kłos, 2006;Malinowska, Lefeld-Sosnowska, Wieteska et al, 2006a,b;Malinowska et al, 2008Malinowska et al, , 2009. Investigations performed by monochromatic beam synchrotron radiation back-reflection topography revealed a 'dotted' fine structure of the linear diffraction contrast corresponding to a row of defects.…”

“…Investigations performed by monochromatic beam synchrotron radiation back-reflection topography revealed a 'dotted' fine structure of the linear diffraction contrast corresponding to a row of defects. The individual defects, 'rods' arranged in rows and aligned in the {100} or {110} lattice planes, were also observed by means of optical transmission microscopy (Malinowska, Lefeld-Sosnowska, Wieteska et al, 2006a,b;Malinowska et al, 2008Malinowska et al, , 2009.…”

“…The diffraction contrast of the investigated defects does not vanish in topographs taken for different azimuths and reflections; therefore it could not be attributed to dislocations. Considering the dependence of the diffraction contrast on the direction of the diffraction vector g with respect to the row of defects, it was concluded that the resulting strains are mainly in the direction perpendicular to the walls of rods (Malinowska et al, 2008(Malinowska et al, , 2009.…”