Phase-Changing in Graphite Assisted by Interface Charge Injection

Among many phase-changing materials, graphite is probably the most studied and interesting: the rhombohedral (3R) and hexagonal (2H) phases exhibit dramatically different electronic properties. However, up to now the only way to promote 3R to 2H phase transition is through exposure to elevated temperatures (above 1000 °C); thus, it is not feasible for modern technology. In this work, we demonstrate that 3R to 2H phase transition can be promoted by changing the charged state of 3D graphite, which promotes the repulsion between the layers and significantly reduces the energy barrier between the 3R and 2H phases. In particular, we show that charge transfer from lithium nitride (α-Li₃N) to graphite can lower the transition temperature down to 350 °C. The proposed interlayer slipping model potentially offers the control over topological states at the interfaces between different phases, making this system even more attractive for future electronic applications.