Y:BaZrO 3 Perovskite Compounds II: Designing Protonic Conduction by using MD Models

The proton dynamics in Y-doped BaZrO(3) derivatives, in particular the different dopant environments within a Pm3m cubic framework, were studied by using classical molecular dynamics (MD) calculations. Single- and double substitution of zirconium by yttrium atoms was considered. The presence of yttrium induced variations in the surrounding oxygen sites, according to their local geometrical arrangements. The differences among such distinct oxygen sites became evident when protons interacted with them and upon changes in the temperature. So, different proton transfer pathways, which had different energy barriers, characterized the topologically different oxygen sites. The experimental proton-…

Cation Environment of BaCeO3−Based Protonic Conductors II: New Computational Models

Quantum chemical calculations have been carried out to simulate Y-doped BaCeO(3) derivatives. Hartree-Fock energy functional was used to study octahedral site environments embedded in a Pmcn orthorhombic framework, showing local arrangement characterized by Ce-O-Ce, Ce-O-Y, and Y-O-Y (Z-O-Ξ) configurations and including or not hydrogen close to the moieties encompassing those configurations. The latter are, in fact, representative of - and, in our modeling approach, were treated as - local arrangements that could be found in Y:BaCeO(3)-doped materials. The geometrical optimizations performed on the structural models and a detailed orbital analysis of these systems allowed us to confirm and …

Computational Studies of the Structure and of the Proton Transport Phenomena in Systems Derived from Barium Cerate Perovskite Structure

The final task of the whole research project is the design of new ceramic materials for protonic conduction in the range of temperature 350-750 °C. To this aim, it was planned to deepen the information on the systems obtained by doping the Ce site in the BaCeO3 perovskite matrices. In these compounds, cerium has been substituted by trivalent elements (Y, In), thus creating – to fulfill charge neutrality – oxygen vacancies that could be filled by hydroxyls groups. In this way protons have been introduced in the structure. These materials are currently investigated by both experimental and computational approaches to integrate framework structure and proton transport phenomena analyses. Due t…

Y:BaZrO3 Perovskite Compounds I: DFT Study on the Unprotonated and Protonated Local Structures

Y-doped BaZrO(3) derivatives were studied by density functional theory (DFT) to investigate the local arrangements of the octahedral sites in Pm3m cubic frameworks. Single- and double substitution of zirconium by yttrium were considered, including in the presence of a nearby oxygen vacancy. Although the structural symmetry of undoped barium zirconate was not modified after yttrium doping, the presence of yttrium induced several differences in the oxygen sites around it, according to the local geometrical arrangement of yttrium in the host matrix. As an example, the differences between such oxygen sites were shown in the presence of a proton. In this case, different stabilization energies ch…

Cation Environment in BaCeO3-Based Protonic Conductors: a Computational Study

Geometry calculations were performed on pure BaCeO(3) fragments and on Y- and In-doped derivatives. HF and DFT approaches were used to investigate monoclinic and orthorhombic structures. The computational methods, structural models, and electronic structure investigation protocols were tuned taking into consideration and balancing the consistency of the results against the computational cost. The calculated structures and energetics parameter, as well as the detailed orbital analysis performed on the corresponding BaCeO(3) derivatives allowed us to explain experimental findings and to develop a procedure to study the cationic octahedral environment of doped X:BaCeO(3) (X = Y, In) and undope…

Computational studies on systems derived from barium zirconate perovskite structure

In solid oxide protonic conductors, proton diffusion is mainly driven by phonon-assisted dynamics, for this, becoming important local distorsion studies on the lattice, in order to detail the protonic conduction mechanism hence to improve performances of the related materials. Here, the protonic conductor Y:BaZrO3 was studied by means of DFT calculations, using new tetravalent substitution models.

Computational Studies on BaCeO3 and BaZrO3 Derivatives.

Viewpoint: Atomic-Scale Design Protocols toward Energy, Electronic, Catalysis, and Sensing Applications

Nanostructured materials are essential building blocks for the fabrication of new devices for energy harvesting/storage, sensing, catalysis, magnetic, and optoelectronic applications. However, because of the increase of technological needs, it is essential to identify new functional materials and improve the properties of existing ones. The objective of this Viewpoint is to examine the state of the art of atomic-scale simulative and experimental protocols aimed to the design of novel functional nanostructured materials, and to present new perspectives in the relative fields. This is the result of the debates of Symposium I "Atomic-scale design protocols towards energy, electronic, catalysis…