Estudo de estruturas perovskitas do tipo ABO3 através de simulações de dinâmica molecular

Abstract

Technological advancements in computing, as well as improvements in program algorithms within the scope of computational physics, have enabled the application of computational simulations that drive the discovery and analysis of materials. Among the most significant computational advances is the Molecular Dynamics (MD) simulation method, where the structure and behavior of materials under different thermodynamic conditions can be investigated. In the last decade, perovskite-type ceramics have been intensely studied for being promising materials for the fabrication of photovoltaic cells. In addition to their application in solar energy, they have also stood out in the generation of other cleaner energies, such as SOFC-type fuel cells (Solid Oxide Fuel Cell). Silver niobate perovskite (AgNbO3), on the other hand, stands out for its use as a piezoelectric material in various electronic devices, such as capacitors and medical ultrasound tomography. In this work, we seek to explore Molecular Dynamics simulations as a tool to analyze structural, mechanical, and thermal properties of ABO3-type perovskite structures. We focused on different symmetries of silver niobate perovskite (AgNbO3), for which we obtained values comparable to reference values for structural properties such as volume and lattice parameters. We performed the analysis of the radial and angular distribution function, as well as the calculation of the bulk modulus and thermal expansion coefficient. For this, the force field was defined to reproduce the structure by using the Buckingham+Coulomb potential together with the core-shell model. Finally, we also sought to identify crystalline phase transitions and the melting point of the material, but without success. Thus, this work aims to highlight the limitations of the adopted model in not reproducing the structural distortions due to polarization effects and the mixed nature of the bonds present in the material, since it was not possible to adequately reproduce the studied structure.