CO<sub>2</sub>-mediated conversion of physical pressure into chemical pressure to realize lattice strain

<p>Lattice strains often lead to novel phenomena, and they are used in a variety of applications, such as thermoelectricity, ferroelectricity, ferromagnetic, skyrmion and superconductivity. In this paper, we briefly summarize the novel phenomena brought about by lattice strain. An efficient method to realize lattice strain using supercritical CO₂ (SC CO₂) is proposed. When CO₂ molecules shuttle through the confined space of the crystal structure, it can generate huge energy subsequently. Specifically, CO₂ carries MPa-level external physical pressure inside the crystal structure, forming localized defects or phase transitions. This alters the original chemical coordination environment and generates internal chemical pressures up to the GPa level. The crystal is stripped from three-dimensional to two-dimensional under high pressure, and lattice strain is realized at the same time. This work will provide new insights into the realization of lattice strain and give valuable guidance to broaden its application.</p>