Anharmonicity of Thermal Vibrations in Cr Between 297 and 806K

Abstract

The integrated intensities samples were measured at of high order reflections from Cr powder 297, 505, 607, 708 and 806 K using MoKa ..radiation. The temperature dependence of the integrated intensities indicates significant anharmonic contributions, which are parametrized in terms of the effective one-particle potential, V(u) = +U' + 7u4, using quantum statistics. At 297 K, the values (9.27 f 0.37) eV A-' and -(12 f 3) eV A-4 are obtained for the isotropic harmonic and anharmonic potential parameters, respectively. For comparison, the harmonic parameter is calculated using the interatomic force-constants determined from inelastic neutron scattering. Comparison is also made between the classical and quantum approaches.

A study of the structure and thermal parameters of Ni88.6Cr11.4alloy

“…The values of u 2 (T ) were found to be in the range 0.013-0.048 Å 2 for a temperature range 308-1158 K. These values are smaller than u 2 (T ) for pure Ni (0.118 Å 2 ) and Cr (0.097 Å 2 ) [11,17]. The presence of atoms of different sizes at some points that are normally occupied by a given type of atom causes disorder in the lattice [22].…”

“…. The values of D for pure Ni and Cr determined by various investigators lie between 389 and 425 K [7][8][9][10][11][12][13][14][15][16] and between 495 and 541 K [8,12,[16][17][18][19][20], respectively. To the best of our knowledge, no data are available in the literature for any composition of the Ni-Cr alloy.…”

Electron density distribution in paramagnetic chromium: Aγ-ray diffraction study

“…Our result is supported by x-ray single crystal diffraction 17 but disagrees with an x-ray powder study. 20 According to this study, the independently-vibrating atom potential should show an isotropic softening which would imply a larger thermal displacement than in a harmonic potential.…”