[Zurück]

T. Mehaddene, J. Neuhaus, W. Petry, K. Hradil, P. Bourges, A. Hiess:
"Phonon dispersions of Ni-Mn-Al shape memory alloy";
Materials Science and Engineering A, 481-482 (2008), 197 S.

Normal modes of vibration of a Ni-Mn-Al single crystal have been measured by inelastic neutron scattering. The force constants have been fitted to the Born-von Karman model using axially symmetric forces. Dispersion curves of both acoustical and optical phonons have been determined along the high symmetry [1 0 0], [1 1 0] and [1 1 1] directions. The temperature dependence of the normal modes revealed an anomalous softening of the TA2[1 1 0] phonons observed in the range of 0.1-0.25 reciprocal lattice units in good agreement with recent ab initio calculations. Contrary to the acoustical TA2[1 1 0] modes. The optical TO2[1 1 0] modes with the same polarisation showed a normal behaviour with temperature, namely a decrease in frequency upon heating due to increasing anharmonicity. Elastic scattering performed along the [1 View the MathML source 0] direction did not reveal any significant elastic or diffuse scattering.

http://dx.doi.org/10.1016/j.msea.2006.12.198