X-ray fluorescence holography of In1-xGaxSb mixed crystal

The powder X-ray diffraction (PXRD) and X-ray absorption fine structure (XAFS) measurements were performed on In1-xGaxSb mixed polycrystals in the whole x range, and the former indicates Vegard's law, i.e., the lattice constant linearly changes with varying the concentration x, while the latter reveals a Pauling's bond length, i.e., an almost constant In-Sb or Ga-Sb interatomic distance is preserved all over the concentration range. In order to clarify the lattice distortions by adding the Ga atoms, Ga K alpha X-ray fluorescence holography (XFH) experiment was carried out on In0.995Ga0,005Sb mixed single crystal, and a three-dimensional atomic image around the Ga atoms was constructed. Although the atomic images locate almost on the atomic positions of the InSb crystal, some deviations (distortions from the lattice) can be observed, in particular for the first-, and second-nearest-neighboring atoms. We found that the lattice distortion by the Ga atoms is induced within the fifth neighbor atoms. From the XFH result, we discuss how the small GaSb4 tetrahedra can be stably located in the InSb lattice with the larger lattice constant. (c) 2008 Elsevier B.V. All rights reserved.