Hai Nan

To study the crystal mechanical properties of 3,4-dinitrofurazanofuroxan (DNTF) and hexanitrohexaazaisowurtzitane (CL-20) deeply, the crystals of DNTF and CL-20 were prepared by the solvent evaporation method. The crystal micromechanical loading procedure was characterized by the nanoindentation method, and then obtained the mechanical parameters. In addition, the crystal fracture behaviors were investigated with scanning probe microscopy (SPM). The results show that the hardness for DNTF and CL-20 was 0.57 GPa and 0.84 GPa, and the elastic modulus was 10.34 GPa and 20.30 GPa, respectively. CL-20 obviously exhibits a higher hardness, elastic modulus and local energy-dissipation and a smaller elastic recovery ability of crystals than those of DNTF. CL-20 crystals are more prone to cracking and have a lower fracture toughness value than DNTF. Compared to DNTF crystals, CL-20 is a kind of brittle material with higher modulus, hardness and sensitivity than that of DNTF, making the ignition response more likely to happen.

In the present study, the effects of pressure on the structure, elastic properties and electronic structure of DNTF compounds are studied using the first principles method. It is found that pressure has a great influence on lattice constants. When the pressure reaches 80 GPa, the structure of DNTF changes suddenly. The variation trend of C₁₁, C₂₂ and C₃₃ values is consistent with that of pressure. In addition, pressure can improve the compressibility and shear resistance of the DNTF compound. The pressure can reduce the bandgap and further increases the charge density, causing DNTF to decompose and explode.