TiGePt--a study of Friedel differences

Acta Crystallogr B Struct Sci Cryst Eng Mater. 2013 Oct;69(Pt 5):457-64. doi: 10.1107/S2052519213021635. Epub 2013 Sep 19.

Abstract

The X-ray single-crystal diffraction intensities of the intermetallic compound TiGePt were analysed. These showed beyond doubt that the crystal structure is non-centrosymmetric. The analysis revolves around the resonant-scattering contribution to differences in intensity between Friedel opposites hkl and \bar h\bar k\bar l. The following techniques were used: R(merge) factors on the average (A) and difference (D) of Friedel opposites; statistical estimates of the resonant-scattering contribution to Friedel opposites; plots of 2A(obs) against 2A(model) and of D(obs) against D(model); the antisymmetric D-Patterson function. Moreover it was possible to show that a non-standard atomic model was unnecessary to describe TiGePt. Two data sets are compared. That measured with Ag Kα radiation at 295 K to a resolution of 1.25 Å(-1) is less conclusive than the one measured with Mo Kα radiation at 100 K to the lower resolution of 0.93 Å(-1). This result is probably due to the fact that the resonant scattering of Pt is larger for Mo Kα than for AgKα radiation.

Keywords: D-Patterson; Friedel differences; intermetallic compound.

MeSH terms

  • Crystallography, X-Ray
  • Germanium / chemistry*
  • Models, Molecular
  • Platinum / chemistry*
  • Titanium / chemistry*

Substances

  • Germanium
  • Platinum
  • Titanium