Pressure aging: An effective process to liberate the power of high-pressure materials research

High pressure can create extreme conditions that enable the formation of novel materials and the discovery of new phenomena. However, the ability to preserve the desirable characteristics of materials obtained under high pressure has remained an elusive challenge, as the pressure-induced changes are typically reversible, except for the pressure-induced chemical reactions such as polymerization of hydrocarbons. Here, we propose the concept of "pressure aging" (PA) that enables the permanent locking-in of high-pressure structures and their associated enhanced properties in functional materials. Specifically, through the application of PA at 3.3 GPa for 24 h, the two-dimensional ferroelectric CuInP₂S₆ exhibits a permanent change in Cu configuration after the pressure is fully released. This leads to a 2.5-fold enhancement in remanent polarization and an increase in T_c from 317 K to 583 K. In contrast, the samples underwent a compression-decompression cycle but without PA showed only reversible changes in their characteristics. We elucidate the relaxation dynamics during PA using the Kohlrausch-Williams-Watts function, providing valuable insights into the temporal evolution of both structural and property changes. Furthermore, the broad applicability of PA strategy has been validated across different materials, underscoring its versatility. Notably, the pressures involved are industrially attainable, and the sample sizes are scalable. Consequently, the implementation of this impactful PA approach introduces a groundbreaking unique dimension to high-pressure research, with significant potential across various scientific domains.