Phonon density of states in nanocrystalline 57Fe

2020-01-03 03:30:59

The Fe nanocrystalline modes phonon

责任者: Singh, R.;Prakash, S.;Meyer, R.;Entel, P. 单位: Dept. of Phys., Panjab Univ., Chandigarh, India 来源出处: Pramana, Journal of Physics(Pramana J. Phys. (India)),2003/03/,60(3):547-56 摘要: The Born-von Karman model is used to calculate phonon density of states (DOS) of nanocrystalline BCC Fe. It is found that there is an anisotropic stiffening in the interatomic force constants and hence there is shrinking in the nearest-neighbour distances in the nanophase. This leads to additional vibrational modes above the bulk phonons near the bottom of the phonon band. It is found that the high energy phonon modes of nanophase Fe are the surface modes. The calculated phonon DOS closely agree with the experimental data except a peak at 37 meV. The calculated phonon dispersion relations are also compared with those of the bulk phonons and anomalous behaviour is discussed in detail. The specific heat in nanophase enhances as compared to bulk phase at low temperatures and the calculated Debye temperature ΘD agrees with the experimental results. It is predicted that the nanocrystalline Fe may consist of about 14 GPa pressure 关键词: Debye temperature;iron;nanostructured materials;phonon dispersion relations;specific heat;surface phonons;vibrational modes;phonon density of states;nanocrystalline 57Fe;Born-von Karman model;anisotropic stiffening;interatomic force constants;nearest-neighbour distances;vibrational modes;bulk phonons;high energy phonon modes;surface modes;phonon dispersion relations;anomalous behaviour;specific heat;Debye temperature;37 meV;14 GPa;Fe