X-RAY DETERMINATION OF ANHARMONICITY IN V3SI

X-ray intensities from over 1000 reflections in single-crystal V3Si at 300, 78, and 13.5 K, previously obtained by one of us (J.-L.S.) have been analyzed for anharmonicity when λ-1sinθ>0.7 -1 where diffraction occurs from core electrons only. At 78 K we find moments for V which are ∼ 50% and 500% larger, respectively, than expected for a harmonic lattice, and evidence for localization of the V atoms off the lattice sites by ∼0.2 . No evidence of such large anharmonicity is found for Si atoms at all three temperatures. © 1979 The American Physical Society.