Surface phase diagrams from nested sampling.

Studies in atomic-scale modeling of surface phase equilibria often focus on temperatures near zero Kelvin due to the challenges in calculating the free energy of surfaces at finite temperatures. The Bayesian-inference-based nested sampling (NS) algorithm allows for modeling phase equilibria at arbitrary temperatures by directly and efficiently calculating the partition function, whose relationship with free energy is well known. This work extends NS to calculate adsorbate phase diagrams, incorporating all relevant configurational contributions to the free energy.

Engineering Relaxor Behavior in (BaTiO ) /(SrTiO ) Superlattices.

Complex-oxide superlattices provide a pathway to numerous emergent phenomena because of the juxtaposition of disparate properties and the strong interfacial interactions in these unit-cell-precise structures. This is particularly true in superlattices of ferroelectric and dielectric materials, wherein new forms of ferroelectricity, exotic dipolar textures, and distinctive domain structures can be produced. Here, relaxor-like behavior, typically associated with the chemical inhomogeneity and complexity of solid solutions, is observed in (BaTiO ) /(SrTiO ) (n = 4-20 unit cells) superlattices.

Factors Governing Oxygen Vacancy Formation in Oxide Perovskites.

The control of oxygen vacancy (V) formation is critical to advancing multiple metal-oxide-perovskite-based technologies. We report the construction of a compact linear model for the neutral V formation energy in ABO perovskites that reproduces, with reasonable fidelity, Hubbard--corrected density functional theory calculations based on the state-of-the-art, strongly constrained and appropriately normed exchange-correlation functional. We obtain a mean absolute error of 0.

Large-area synthesis of high-quality monolayer 1T'-WTe flakes.

Large-area growth of monolayer films of the transition metal dichalcogenides is of the utmost importance in this rapidly advancing research area. The mechanical exfoliation method offers high quality monolayer material but it is a problematic approach when applied to materials that are not air stable. One important example is 1T'-WTe, which in multilayer form is reported to possess a large non saturating magnetoresistance, pressure induced superconductivity, and a weak antilocalization effect, but electrical data for the monolayer is yet to be reported due to its rapid degradation in air.

Chemical Pressure-Driven Enhancement of the Hydrogen Evolving Activity of NiP from Nonmetal Surface Doping Interpreted via Machine Learning.

The activity of NiP catalysts for the hydrogen evolution reaction (HER) is currently limited by strong H adsorption at the Ni-hollow site. We investigate the effect of surface nonmetal doping on the HER activity of the NiP termination of NiP(0001), which is stable at modest electrochemical conditions. Using density functional theory (DFT) calculations, we find that both 2 p nonmetals and heavier chalcogens provide nearly thermoneutral H adsorption at moderate surface doping concentrations.

Role of proton hopping in surface charge transport on tin dioxide as revealed by the thermal dependence of conductance.

The presence of water on an oxide surface can dramatically alter its electrical properties with important consequences for electrical measurements by scanning probe microscopy, and for the use of semiconducting oxides in sensing applications. Here, the thermal dependence of the conductance of tin dioxide is interpreted by combining semiconductor equilibrium carrier statistics with a proton hopping mechanism. First, the functional form of this charge transport model is fit to experimental conductance data for tin dioxide.