Lattice Dynamics and Thermal Expansion of Thulium

The lattice dynamics, lattice specific heat and thermal expansion of the rare-earth metal thulium are worked out applying a model based on Keating’s method. A frequency distribution function involving 50,880 frequencies has been employed. Using the calculated lattice heat capacity, the experimental Cp data of thulium are analysed to get the magnetic contribution to the specific heat in this metal. The energy of magnetic ordering and the magnetic entropy increase involved in the transition from the ordered antiferromagnetic phase to the disordered paramagnetic phase are evaluated. The lattice parameters and volume of thulium are also calculated as a function of hydrostatic pressure and compared with the experimental results. © 1979, Walter de Gruyter. All rights reserved.