LAUSR

Abstract Ytterbium doped calcium gadolinium aluminate (CaGdAlO 4 ) crystals, which is a perspective material for femto-second lasers, have been studied by means of synchrotron and conventional X-ray diffraction topography. The investigation was performed with a series of samples cut out perpendicularly and parallel to the 〈100〉 growth axis from the initial and end parts of CaGdAlO 4 crystals, both undoped and doped with different concentration of Yb. The synchrotron topographic investigation was performed at the European Synchrotron (ESRF) in transmission geometry using the radiation of rather short wavelength, while the conventional topographs were obtained in the back-reflection geometry by means of the double crystal method in Cu K α1 radiation. Some additional investigation was performed with polarization microscopy and high resolution X-ray diffraction omega scan. Apart from slightly pronounced segregation fringes and a core region the diffraction topographs revealed numerous volume defects, which most probably can be interpreted as solute trails. A characteristic feature of the presently observed volume defects were the details of the contrasts on their boundaries. These details suggested the presence of strong stress and the generation of the dislocations. The increase of the defect concentration with the increase in ytterbium concentration was observed.