Previous experimental studies have shown that the magnetic dipolar interaction plays an important role in several magnetic properties of nanoparticulated systems. More recently, this type of interaction was detected in microparticles of Fe-Mn-Al, Fe-Si and Fe-Al systems. In this work, we apply the Mørup-Tronc (Phys. Rev. Lett. 72:3278, 1994) model for nanoparticulated systems in order to calculate some thermodynamic properties of these systems. We first calculated the total energy of a magnetic particle as the sum of its anisotropy energy and its total dipolar magnetic interaction with the other particles. The calculation is performed in such a way that the interaction energy has the same form as the anisotropy energy. We use the total energy to calculate the magnetization, heat capacity, magnetic susceptibility, and blocking temperature in nanoparticulated systems. The application of our theory to experimental data on nanoparticulated systems and for the Fe-Al, Fe-Si and Fe-Mn-Al microparticulated granular systems will be presented elsewhere.

No abstract

No abstract

No abstract

With the aim to model the propagation of sound pressure emitted by a source, based on the postulates of Far from equilibrium thermodynamics theory, a wave equation was constructed. The equation obtained is a classic generalized wave equation adding dissipative behavior as a function of the media in which wave propagates. The new equation is of Maxwell-Cattaneo-Vernotte type. Also, an experimental activity was realized and the results were in accordance with theoretical solution of the new differential equation.