Impact of Atomic Defects on Ceria Surfaces on Chemical Mechanical Polishing of Silica Glass Surfaces.

This study investigates the impact of atomic defects, such as oxygen vacancies and Ce ions, on cerium oxide (ceria) surfaces during chemical mechanical polishing (CMP) for silica glass finishing. Using density functional theory (DFT) and reactive molecular dynamics simulations, the interaction of orthosilicic molecules and silica glass with dry and wet ceria surfaces is explored. Defects alter the surface reactivity, leading to the dissociation of orthosilicic acid on oxygen vacancies, forming a strong Si-O-Ce bond.

New Atomistic Insights on the Chemical Mechanical Polishing of Silica Glass with Ceria Nanoparticles.

Reactive molecular dynamics simulations have been used to simulate the chemical mechanical polishing (CMP) process of silica glass surfaces with the ceria (111) and (100) surfaces, which are predominantly found in ceria nanoparticles. Since it is known that an alteration layer is formed at the glass surface as a consequence of the chemical interactions with the slurry solutions used for polishing, we have created several glass surface models with different degrees of hydroxylation and porosity for investigating their morphology and chemistry after the interaction with acidic, neutral, and basic water solutions and the ceria surfaces. Both the chemical and mechanical effects under different pressure and temperature conditions have been studied and clarified.

HOadsorption and dissociation on various CeO(111) surface models: a first-principles study.

Periodic density functional theory (DFT) calculations using the hybrid PBE0 functional and atom-centered Gaussian functions as basis sets were carried out to investigate the absorption and the first steps involved in the decomposition of hydrogen peroxide (HO) on three different models of the ceria (111) surface. One of the models is a clean surface, and the others are defective and partially hydroxylated ceria surfaces. On the clean surface, we found that the minimum energy path of hydrogen peroxide decomposition involves a three-step process, i.

Development and Application of a ReaxFF Reactive Force Field for Cerium Oxide/Water Interfaces.

Ceria (CeO) is a well-known catalytic oxide with many environmental, energy production, and industrial applications, most of them involving water as a reactant, byproduct, solvent, or simple spectator. In this work, we parameterized a Ce/O/H ReaxFF for the study of ceria and ceria/water interfaces. The parameters were fitted to an training set obtained at the DFT/PBE0 level, including the structures, cohesive energies, and elastic properties of the crystalline phases Ce, CeO, and CeO; the O-defective structures and energies of vacancy formation on CeO bulk and CeO (111) surface, as well as the absorption and reaction energies of H and HO molecules on CeO (111).

Assessment of Density Functional Approximations for Highly Correlated Oxides: The Case of CeO and CeO.

CeO based materials are very attractive as catalytic components for industrial processes and environmentally friendly technologies; therefore, a reliable and computationally affordable theoretical description of the main properties of ceria is needed. In particular, the description of the interconversion between the Ce(IV) and Ce(III) oxidation states, on which lies the main chemical features of the cerium oxide, results in quite a challenge at the Density Functional Theory level. Here, we tested several density functional approximations, spanning from GGA to hybrid (Global, Meta-Global, and Range Separated Corrected) functionals, on the structural, vibrational, electronic, and thermochemical properties of bulk CeO and CeO.