Title: First-Principles Modeling of Yttrium Oxide and Oxyhydride: Defects, Electronic Properties, and Applications in Smart Materials
Research proposal No: 1.1.1.9/LZP/1/24/012
Duration: 01.03.2025.-29.02.2028.
Project Leader: Dr.phys. Aleksejs Gopejenko
Total budget: 184 140 EUR
European Regional Development Fund (ERDF) funding: 156 519 EUR
ISSP UL budget: 9 207 EUR
Project description:
The aim of the project is to develop reliable first-principles computational models for rare earth oxides and oxyhydrides, focusing on YO and YHO. These materials have promising applications in energy-efficient technologies like smart windows. The study explores how structural composition and defects affect their properties, supporting the development of innovative functional materials.
PROJECT PROGRESS
Time period: 01.03.2025. – 28.08.2025.
Work Package 1 (WP1) was dedicated to the adjustment of computational parameters and the development of a theoretical model for the reliable prediction of the bulk and electronic properties of Y, YO, and YHO (Month 1–Month 6). The objectives of WP1 have been fully accomplished.
A comprehensive verification of computational parameters was performed to ensure accuracy and reproducibility of the results. The influence of the Monkhorst-Pack mesh on Brillouin zone sampling, as well as the convergence behavior of bulk and supercell calculations, was systematically analyzed. Particular attention was given to the convergence of defect supercells in order to minimize artificial interactions between periodic images. Several exchange–correlation functionals were tested, and the final computational protocol was established on the basis of consistency and agreement with reference data. The reliability of the chosen model was further confirmed by validation against available experimental measurements and theoretical studies.
Main Results
The equilibrium lattice constant of YO was calculated as 4.78 Å, in very good agreement with the reported value of 4.87 Å.
Analysis of the electronic density of states (DOS) demonstrated that YO exhibits metallic-like behavior, with oxygen atoms dominating the valence band and yttrium atoms dominating the conduction band.
Hydrogen incorporation into YO (YOH) resulted in a lattice expansion to 5.61 Å, accompanied by local lattice distortions depending on the positioning of hydrogen atoms in tetrahedral interstitial sites.
YOH was identified as a semiconductor with a calculated band gap of 3.13 eV. The valence band is primarily composed of contributions from oxygen and hydrogen, while the conduction band is dominated by yttrium.
These findings establish that hydrogen incorporation has a pronounced effect on both the structural and electronic properties of YO, inducing a transition from metallic-like to semiconducting behavior.
Ongoing Work
The implementation of WP2 is in progress, ensuring the continuity of the research program. Calculations of the Y lattice containing O and H defects have been initiated. These studies will provide further insight into defect-driven modifications of the structural and electronic properties of yttrium-based materials.
Conclusion
The activities of WP1 have been completed in full. The computational framework has been optimized, a validated theoretical model has been established, and the bulk and electronic properties of Y, YO, and YHO have been systematically characterized. The results obtained provide a robust foundation for subsequent investigations of defect structures and functional properties in rare-earth oxide materials.