Diamond is a symbolic material in nature due to its extremely high hardness. The Hugoniot-elastic limit (HEL) under shock compression can be used as an alternative method to evaluate the strength of a material. We measured the HELs of three types Ia-, Ib-, and IIa-diamond single crystals using large samples (thickness: 1.12–2.50 mm) in the peak stress range up to 119 GPa by a velocity-interferometer system of any reflector (VISAR). A minimum constant (steady-state) HEL value of $20.5\pm 2.0$ GPa was obtained for the highly pure type IIa-diamond large single crystals (nitrogen content: $<0.1$ ppm, thickness: 1.52–1.92 mm) along the $\langle 100\rangle$ axis, although the values in the range of 35–53 GPa were obtained for type Ia- and type Ib-diamond large single crystals (nitrogen content:10–2000 ppm, thickness: 1.42–2.50 mm). Considering these and previous reported results for thin diamond samples (thickness: 0.08–0.51 mm), we suggested that our steady-state HEL of type IIa-diamond single crystals was inherent for diamond and that the intrinsic strength was $18.4\pm 2.0$ GPa. The slip system was confirmed to be the {111} plane by the transmission electron microscopy observation of the recovered sample. The critical resolved shear stress of the {111}[110] slip system was derived to be $7.5\pm 1.0$ GPa, which can be comparable with the Peierls stress of diamond.

Close

PrevNext

View figure in article

• Compressive strength
• Crystal phenomena
• Dynamical phase transitions
• Pressure effects