No abstract

A spin-1/2 Ising model, with nearest-neighbor exchange and next-nearest-neighbor superexchange interactions, is proposed to describe the phase diagram of disordered Fe p -Al q (p + q = 1) alloys in the body centered cubic lattice. The size of the aluminum clusters have been taken into account in order to induce a superexchange interaction among the Fe atoms. Extensive Monte Carlo simulations have been employed by using a hybrid algorithm consisting of Metropolis spin flip and Wolff cluster algorithm, together with single histograms techniques. A good fit to the experimental phase diagram has been achieved, including the anomalous region for Al concentration in the range q ≤ 0.2.

In textbooks the subject of chemical reactions is worked mechanically. Our task as teachers was to modify teaching, that is, the approach to the theme was based on the integration of the concept of chemical reactions and the discussion of the social aspect with the theme "Drugs". The project was developed with students of the first year of high school, in a public school in Aracaju-Sergipe. Several methodologies were used, among them a playful game of puzzle, film and discursive classes. This method was satisfactory, allowing to verify the difficulties of the students and contributing to a significant learning and for the formation of conscious and active citizens.