Vacuum sintering‐induced oxygen vacancies and their role in the densification of TiO ₂ ceramics:Experiment and simulation

Abstract In this work, the influence of vacuum sintering on the sintering behavior of TiO 2 ceramics was systematically investigated, and the role of oxygen vacancies was elucidated through a combination of experimental observations and theoretical calculations. Vacuum heat treatment induced phase transformation from anatase to rutile and generated oxygen vacancies in TiO 2 powders, as confirmed by X‐ray diffractometer, X‐ray photoelectron spectroscopy, and transmission electron microscopy. Sintering experiments revealed that vacuum conditions significantly enhanced densification and grain growth compared to air, achieving lower porosity and higher density at identical temperatures. To further analyze the role of oxygen vacancies, density functional theory calculations and phase‐field simulations were employed. It was revealed that the formation of oxygen vacancies was associated with energy absorption, which was subsequently released during sintering, facilitating diffusion processes and accelerating ceramic densification. These findings indicate that the vacuum environment not only influences phase transformation and oxygen vacancy concentration in TiO 2 ceramics but also optimizes microstructure and densification by regulating sintering kinetics. This work provides a deeper understanding of the mechanisms governing vacuum‐assisted sintering of TiO 2 ceramics and offers theoretical guidance for performance optimization in photocatalysis, energy storage, and optoelectronic applications.