Transport Properties of Doped Wide Band Gap Layered Oxychalcogenide Semiconductors SrGaOCu, SrScOCu, and SrInOCu ( = S or Se).

The structural, electrical, and optical properties of a series of six layered oxychalcogenides with the general formula Sr OCu, where M = Ga, Sc, or In and = S or Se, have been investigated. From this set, we report the structure and properties of SrGaOCuSe for the first time, as well as the full structural details of SrScOCuSe, which have not previously been available. A systematic study of the suitability of all of the Sr OCu phases as -type conductors has been carried out, after doping with both sodium and potassium to a nominal composition of Sr OCu, ( = Na or K), to increase the hole carrier concentration.

Accessible chemical space for metal nitride perovskites.

Building on the extensive exploration of metal oxide and metal halide perovskites, metal nitride perovskites represent a largely unexplored class of materials. We report a multi-tier computational screening of this chemical space. From a pool of 3660 ABN compositions covering I-VIII, II-VII, III-VI and IV-V oxidation state combinations, 279 are predicted to be chemically feasible.

Non-volatile electric-field control of inversion symmetry.

Competition between ground states at phase boundaries can lead to significant changes in properties under stimuli, particularly when these ground states have different crystal symmetries. A key challenge is to stabilize and control the coexistence of symmetry-distinct phases. Using BiFeO layers confined between layers of dielectric TbScO as a model system, we stabilize the mixed-phase coexistence of centrosymmetric and non-centrosymmetric BiFeO phases at room temperature with antipolar, insulating and polar semiconducting behaviour, respectively.

Physics-Guided Descriptors for Prediction of Structural Polymorphs.

We develop a method combining machine learning (ML) and density functional theory (DFT) to predict low-energy polymorphs by introducing physics-guided descriptors based on structural distortion modes. We systematically generate crystal structures utilizing the distortion modes and compute their energies with single-point DFT calculations. We then train a ML model to identify low-energy configurations on the material's high-dimensional potential energy surface.

Liberating a hidden antiferroelectric phase with interfacial electrostatic engineering.

Antiferroelectric materials have seen a resurgence of interest because of proposed applications in a number of energy-efficient technologies. Unfortunately, relatively few families of antiferroelectric materials have been identified, precluding many proposed applications. Here, we propose a design strategy for the construction of antiferroelectric materials using interfacial electrostatic engineering.

Bending Rules in Graphene Kirigami.

The three-dimensional shapes of graphene sheets produced by nanoscale cut-and-join kirigami are studied by combining large-scale atomistic simulations with continuum elastic modeling. Lattice segments are selectively removed from a graphene sheet, and the structure is allowed to close by relaxing in the third dimension. The surface relaxation is limited by a nonzero bending modulus which produces a smoothly modulated landscape instead of the ridge-and-plateau motif found in macroscopic lattice kirigami.