Materials science. The hardest known oxide.
A material as hard as diamond or cubic boron nitride has yet to be identified, but here we report the discovery of a cotunnite-structured titanium oxide which represents the hardest oxide known. This is a new polymorph of titanium dioxide, where titanium is nine-coordinated to oxygen in the cotunnite (PbCl2) structure. The phase is synthesized at pressures above 60 gigapascals (GPa) and temperatures above 1,000 K and is one of the least compressible and hardest polycrystalline materials to be described.
Dubrovinsky
L S
LS
Institute of Earth Sciences, Uppsala University, S-752 36 Uppsala, Sweden. leonid.dubrovinsky@geo.uu.se
Dubrovinskaia
N A
NA
Swamy
V
V
Muscat
J
J
Harrison
N M
NM
Ahuja
R
R
Holm
B
B
Johansson
B
B