Electronic and structural properties of ABO4 compounds (A = Ba, Ca, Cd, Sr and Pb and B = Mo and W) and modeling of morphological transformations of their nanoparticles

Author(s)

José Artigas dos Santos Laranjeira

• Document type: Master's Dissertation
• Press: Bauru. 2023-03-01.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Ciências. Bauru
• Defense date: 2023-01-13
• Advisor: Julio Ricardo Sambrano

Abstract

The morphology of a nanostructured material is decisive for its properties. This dependence is derived from the nanoparticle surface regions that possess lower coordination atoms than that of the material in bulk form. Therefore, great efforts have been made to study surface chemical and physical characteristics through the knowledge of their terminations, stability and reactivity. Determining these parameters is still not trivial for experimentalists, so electronic structure calculations based on the Density Functional Theory (DFT) have been useful. The success of studying the morphology of nanoparticles via computational modeling depends on the accurate simulation of each of its faces, which means knowing which is the arrangement of the outermost atoms that correspond to the geometry of lower energy. Only in this way can it provide information regarding its structural and electronic properties compatible with experimental data. Metallic molybdates and tungstates with a structure of the ABO4 scheelite type, where A = Ba, Ca, Cd, Pb or Sr and B = Mo or W, have been the source of several studies and research due to their excellent optical and electronic properties, high surface, number of active sites and high selectivity. With that in mind, this work performs modeling and computational simulation via density functional theory (DFT) applied to periodic models of ABO4 compounds. The effects of changes in the lattice former (B) and lattice modifiers (A) were analyzed in each structure and the relative stability order of the surfaces. A general mapping of morphological transformations was done for any material that exhibits the symmetry of the scheelite group. Routes of morphological transformations were proposed, which, when associated with experimental results, can explain and predict the surfacedependent properties of these compounds. The present research can help experimentalists understand and direct the control of the synthesis of the shape of ABO4 systems, besides indicating unknown properties and possible applications for these materials. (AU)

• FAPESP's process: 20/01144-0 - Electronic, structural properties of ABO4 compounds (A = Ba, Ca, Cd, Sr and Pb and M = Mo and W) and modeling of morphological transformations of their nanoparticles
• Grantee: José Artigas dos Santos Laranjeira
• Support Opportunities: Scholarships in Brazil - Master