Morphological control of zinc tricarbohydrazide perchlorate crystals: Theoretical and experimental study

Abstract

The theoretical crystal-morphology of zinc tricarbohydrazide perchlorate (ZnCP) was studied using the morphology simulation software. The growth trends and surface characteristics were calculated using the Bravais-Friedel-Donnay-Harker (BFDH), Growth Morphology, and Equilibrium Morphology methods; these provide theoretical guidance for the choice of crystal-control reagents. On the basis of the simulations, experiments were carried out to study the effects of five different crystal-control reagents, including carboxymethylcellulose (A), polyacrylamide (B), dextrin (C), Tween 40 (D), and Tween 60 (E), in the control of the crystal-morphology of ZnCP. Mixtures of two reagents and higher temperatures were used to further optimize the ZnCP crystals. The results show that ZnCP crystals are well dispersed, and have a large apparent density and regular crystal-morphology under the control of a mixture of reagents A and E in a mass ratio of 1:4 at 80°C. The crystal-morphology of an energetic material has a direct effect on its physical properties such as fluidity, apparent density, electrostatic accumulation, and pressure resistance, and even has an important impact on its chemical and explosive properties such as stability, detonation ability, and sensitivity [1,2]. Generally, a material with a smooth surface, uniform particles, and spherical crystals has many advantages over needle-or twig-like irregular crystals, such as good fluidity, high apparent density (more than 0.8 g/cm 3 ), low sensitivity, and stable performance [3,4]. A fine crystal-morphology plays an important role in the safety and stability of a material [5][6][7]. Methods for controlling crystal-morphology can therefore be used to regulate nucleation and crystal growth during the crystallization process to increase the production and use of security of energetic materials, and improve their energy output performances [8][9][10][11][12]. Zinc tricarbohydrazide perchlorate ([Zn(CHZ) 3 ](ClO 4 ) 2 , ZnCP) is a new green energetic coordination compound that excludes toxic heavy metals [13]. However, ZnCP crystals prepared using traditional synthetic techniques are too small, fragmented, and irregular, and have poor fluidity and a small apparent density (less than 0.7 g/cm 3 ), leading to weak explosive power. Crystal-morphology control using a crystalcontrol reagent would improve the crystal quality, and enable ZnCP to be used as a green energetic material in practical applications.In this study, the crystal-morphology and crystal-face parameters of ZnCP were simulated using the Morphology module of the Materials Studio simulation software (MS Morphology, Accelrys Corp., San Diego, CA, USA). Based on the theoretical calculations, experiments were performed to select the optimum crystal-control reagents and reaction conditions for the crystal-morphology optimization of ZnCP.

Size-dependent thermal decomposition and kinetics of ultrafine alkali metal styphnates

“…It not only reduces the surface tension of the formed crystal but also increases the diffusion coefficient of solute and the viscosity of solution, which lead to a decrease in the rates of nucleation and crystal-growth. [42][43][44][45][46] Thus, the M 2 TNR crystal tends to grow into a micron-sized spheroid and form into different sizes by varying the concentration of reagent. Furthermore, the same crystal-control reagent has the same effect on the improvement of the morphology and size of the styphnates, which are coordinated with different metals.…”

Electric-field-induced structural and electronic changes and decomposition of an energetic complex: a computational study on zinc carbohydrazide perchlorate crystals

“…Thereby, the structure, thermal decomposition and sensitivity of ZnCP have been extensively investigated and compared. [32][33][34][35] Unfortunately, the geometric and electronic structures and decomposition mechanism under external electric eld are oen difficult to obtain from experiment for practical reasons. Compared with experiment, simulation can provide more detailed information about variations in crystal and molecular structures, initiation mechanism, and stability of energetic materials under applied electric eld.…”