Malcolm McMahon

Prof McMahon's research is in the behaviour of materials at extremes of pressure and temperature. At extreme pressures, where atoms are pushed close together, it was long assumed that all materials would become metallic, with simple, close-packed crystal structures. By investigating the structures of materials under such conditions using synchrotron radiation, McMahon’s research has shown that this is untrue, and that even the simplest of elements adopt wholly unexpected structural complexity at high density. The array of complex and incommensurate structures that has been unveiled are unlike anything seen at ambient conditions. In addition to using synchrotron storage rings, McMahon also uses large laser platforms and x-ray lasers to investigate the behaviour of materials under dynamic compression on femtosecond timescales.

[2026] Crystal structures of ytterbium to 293 GPa [2026] Broadening and displacement of x-ray powder diffraction lines under nonhydrostatic stress: Cubic, hexagonal, and tetragonal materials [2026] Phase transitions in Zr to 240 GPa [2026] A closer look under extreme pressure: sub-micron diffraction mapping in a diamond anvil cell [2026] Metrology for femtosecond pulsed x-ray heating in diamond anvil cell experiments at the European XFEL: Revisiting the iron phase diagram up to 150 GPa