Controlled crystallization and morphology optimization of premium-grade spheroidal dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate

Abstract

Dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (HATO), a monocomponent explosive combining high energy density with low sensitivity, faces practical limitations due to irregular crystal morphology and intrinsic defects in directly synthesized products. To achieve premium-grade HATO crystals, this study integrates crystallization thermodynamics, molecular dynamics (MD) simulations, and experimental optimization to realize spheroidal crystallization control. Solubility profiles of HATO in water, formic acid, acetic acid, ethanol, and binary solvent systems (formic acid–water, acetic acid–water, ethanol–water) were systematically determined. Thermodynamic parameters derived via van't Hoff equation fitting revealed the formic acid–water system (volume ratio 2 : 8) exhibits optimal dissolution behavior governed by enthalpy-driven mechanisms. MD simulations further predicted minimal growth rate disparities among crystal planes in this solvent system, favoring near-spheroidal morphological evolution. Guided by thermodynamic and computational insights, orthogonal experimental design optimized crystallization parameters: supersaturation ratio 0.9, cooling rate 0.5 °C h⁻¹, and agitation speed 500 rpm. Resultant HATO crystals demonstrate exceptional sphericity, enhanced density, improved thermal stability, and significantly reduced mechanical sensitivity. This research establishes a robust framework for scalable production of premium-grade spheroidal HATO crystals, advancing industrial safety and detonation performance.