Crystal Structure of Rb4C60 and K4C60 under Pressure

TL;DR

This study investigates how applying pressure alters the crystal structures of Rb4C60 and K4C60, revealing a pressure-induced phase transition in Rb4C60 that could impact understanding of their electronic properties.

Contribution

It reports the pressure-induced structural transition of Rb4C60 from disordered to ordered form, providing insights into pressure effects on fulleride electronic phases.

Findings

Rb4C60 transitions to an orthorhombic structure at 0.4 GPa

No structural transition observed in K4C60 up to 2.0 GPa

Potential to study metal-insulator transition via pressure in Rb4C60

Abstract

We show that Rb_4C_60 transforms from its ambient pressure orientationally disordered tetragonal structure to an ordered orthorhombic structure (isostructural to Cs_4C_60) at or above 0.4 GPa. This opens the possibility of studying the previously observed metal-insulator transition under pressure in this narrow band system as a function of a continuous variable, rather than formulating distinct models for conducting and insulating fullerides. No such transition is observed in K_4C_60 to 2.0 GPa