Experimental investigation into polycrystalline and single-crystal diamonds under negative pressures formed by picosecond laser pulses

Results of the experimental investigation of the spallation phenomenon in polycrystalline and single-crystal synthetic diamond are presented. The shock-wave action on the target was formed by a laser pulse with a duration of 70 ps using a Kamerton-T installation. To attain the ablation pressure of 0.66 TPa on the face surface of the target, the laser radiation of the Nd:glass laser (second harmonics λ = 527 nm, the pulse energy is 2.5 J) was used at intensity up to 2 × 1013 W/cm2. The attained maximal spall strength of diamond σ* ∼ 16.5 GPa is 24% of the theoretical ultimate strength. The Raman scattering indicates that a small amount of crystalline diamond is graphitized in the spall region on the back target side.