Synchrotron topographic studies of growth defects in the core of a SrLaGaO₄ single crystal

Abstract

Samples cut out from different regions of SrLaGaO4 (SLG) single crystal grown along [001]‐direction were studied with a number of X‐ray diffraction topographic methods exploring both conventional and synchrotron X‐ray sources. The synchrotron investigation included in particular white beam projection transmission topography at ultra short wavelength and taking monochromatic beam topographs at different points of the rocking curves at different azimuths. The methods enabled the evaluation of the character of lattice deformation connected with the characteristic ‘rod‐like’ defects observed in the core region of the crystal. A shrinkage of the material inside the defects was indicated.

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).…”

“…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.…”

“…A detailed analysis of the diffraction contrast recorded using this method indicated that the observed contrast is caused mainly by lattice bending. This bending is probably due to the shrinkage of the rod-like defects along their lengths (Malinowska et al, 2009). X-ray topography in transmission geometry allows the observation and analysis of the diffraction contrast formed by defects and inhomogeneities inside the whole crystal.…”