Gd-doped diamond synthesized using Gd@C82 under high pressure and high temperature

Abstract

Diamond is an important industrial material with excellent physical properties. Transition-metal-doped diamond materials have unexpected unique optical and magnetic properties, but they are difficult to synthesize. In this work, we synthesized Gd-doped diamond from an endohedral metallofullerene (EMF) under high pressure and high temperature up to 22 GPa and 2100 °C, respectively. During room temperature compression up to 30 GPa, our Raman and IR results show that the carbon cage of Gd@C₈₂ amorphizes, while in situ X-ray diffraction (XRD) data still show clear 100 and 110 peaks, suggesting that the metal is still ordered. At 22 GPa and 2100 °C, carbon transforms into diamond with larger lattice parameters as determined by XRD and high-resolution transmission electron microscopy (HRTEM). Gd distributes uniformly in the diamond lattice, which shows dilute paramagnetic properties and likely exhibits charge transfer between diamond and Gd as tested by energy-dispersive spectroscopy (EDS) mapping, X-ray photoelectron spectroscopy (XPS) and magnetic property measurement system (MPMS). Our work synthesizes a rare-earth metal-doped diamond under high pressure and high temperature and sheds light on the synthesis of other metal-doped diamond materials.