The strength of diamond

Diamond is the hardest known material; however, its mechanical stability, in particular the yield strength sigma(y), is not known. We report reproducible generation of plastic deformation of diamond at room and low temperatures. We determined sigma(y)=130-140 GPa by measuring the pressure distribution over the diamond anvils and by using the theory of elasticity. Yielding in diamond is accompanied by a strong luminescence with a characteristic spectrum. Our findings may be used to extend the static pressure limit beyond the current value of about 300 GPa(3 Megabars). (C) 2005 American Institute of Physics.