Modelagem de filmes finos de estanato de bário fluoretado (BaSnO3:F) por meio da Química Quântica Computacional

Abstract

In the last years, the researches have increased specifically in the computational study through the Quantum Chemistry in the formation of surfaces (001), (011) and (111) of the perovskitas of the ABO3 type (A = mono or divalent ions, B = tri, tetra and pentavalent ions, O = oxygen) of cubic structure belonging to the space group Pm3m, widely used for presenting electrical and magnetic properties applicable. The material under study in this work is barium stanate (BaSnO3), due to its dielectric and semiconductor properties, whose activity in photocatalysis and gas sensing has been reported experimentally, with a band-gap between 2,9 and 3,4 eV. As a sensor, its main applications are as a sensor of humidity and CO, SOx, H2, Cl2 and Liquefied Gas (GLP). The interest in studying BaSnO3 lies in the ability of this material to interact with the atmosphere in which it is included, and can be used in the monitoring of gases and sensors. The improvement of materials for a given application requires the control of phase, morphology, dopants, the electronic structure and the control of punctual defects, in an approach known as Defects Engineering. All computational calculations were performed using Crystal17 software, which considers the correct 2D periodicity of barium stanate thin films (BaSnO3) of the solid state, to obtain structural properties by means of Computational Quantum calculations at the level of the Functional Density Theory (DFT), aiming at understanding the structure, morphology and electronic structure for integrated gas sensing (O2, N2 and NO) and photocatalysis applications. The electronic structure of the films was analyzed based on the band structure, state density and location of the crystalline orbitals. The results showed that the barium stanate presents a certain sensitivity of electrical conductivity stable at temperatures of 1000ºC. And in comparison to the non-doped BaSnO3, the initial calculations showed that the thin films of fluorinated material presented more promising applications as sensors, due to the higher sensitivity and selectivity of NO gas.