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Nicola H. Perry

Publications and source records attributed to Nicola H. Perry.

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Predicting Interface Structure using the Minima Hopping Method with a Machine Learning Interatomic Potential

Predicting atomic-scale interfacial structures remains a central challenge in materials science due to their structural complexity and the difficulty of direct comparison between computational and experimental results. In this study, we present an efficient approach for interface structure prediction that integrates the Minima Hopping Method (MHM) with the state-of-the-art machine learning interatomic potential (MLIP), Allegro. We demonstrate that the MHM-Allegro approach provides a robust and computationally efficient route for predicting interfacial structures in the benchmark system SrTiO3 Sigma 3 (112)[110] tilt grain boundaries (GBs), consistently identifying the lowest-energy configurations across different stoichiometries. Furthermore, we introduce a strategy for constructing defect-representative training datasets without explicitly including defective configurations, achieving excellent extrapolative performance in interface predictions. The predictive capability is further validated through direct comparison with experimental observations of the SrTiO3 Sigma 5 (310)[001] GB, where the predicted atomic configurations show strong agreement with experimental measurements. This work represents a significant step toward bridging the gap between ab initio predictions and experimentally observed interfacial structures.

cond-mat.mtrl-sci

Structural Disorder and Electronic Structure in Alloyed SrTiO3/SrFeO2.5 Compounds: A Theoretical Study

Many mixed ionic/electronic conductors (MIECs) applied in fuel cell electrodes can be considered as alloys between perovskite oxides and ordered oxygen vacancy compounds. For example, in the model MIEC (STF), low oxygen diffusion barrier exist in SrTiO3 lattice, when it has been mixed with SrFeO2.5 with intrinsic oxygen deficiency, the ionic conductivity can be greatly improved. Meanwhile, the electronic conductivity can be optimized by controlling the defect chemistry of the alloy. However, the configurational space is too large in such alloys so that it is difficult for direct atomic modeling, which hinders in-depth understanding and predictive modeling. In this work, we present a cluster expansion model to describe the energetics of the disordered SrTiO3/SrFeO2.5 alloy within the full solid solution composition space Sr(Ti1-x,Fex)O3-0.5x (0<x<1). Cluster expansion Monte Carlo simulations have been performed to search the lowest energy atomic configurations and investigate the origin of lattice disorder. With representations of realistic configurations, the electronic structures of such alloys at different stoichiometry have also been examined. We find that the band gap evolution with composition calculated using our atomic model is consistent with experiment measurement. Meanwhile, the band edge analysis elucidate that electronic conductivity within such alloy can be facilitated by the Fe/Ti cation disorder. Taking SrTiO3/SrFeO2.5 alloy as an example, the generalized computational framework applied here can be extended to other relevant MIEC material systems.

cond-mat.mtrl-sci