Controllable synthesis of perovskite solid solutions as novel energetic materials <i>via</i> thermodynamic equilibrium

Perovskite solid solutions have aroused interest in energy applications, owing to the capability of fine-tuning and enhancing performance to surpass ternary perovskites. Their synthesis, however, is hard to control in solution due to the intricate self-assembly process wherein components crystallize in undetermined ratios. Herein, we present a facile approach to the controllable synthesis of perovskite solid solutions in aqueous solution and develop perovskite solid solutions as a novel class of energetic materials for the first time. Specifically, the composition control of perovskite solid solutions is achieved through thermodynamic equilibrium of reaction crystallization in water, exhibiting a linear relationship with the natural logarithm of reactant concentrations. Based on Goldschmidt's rule, we design a general formula of energetic perovskite solid solutions as (H₂dabco)(NH₄)_(1-<i>x</i>)M _<i>x</i> (ClO₄)₃, in which 0 < <i>x</i> < 1, H₂dabco²⁺ refers to 1,4-diazabicyclo[2.2.2]octane-1,4-diium, and M is a quaternary ion. The as-synthesized (H₂dabco)(NH₄)_(1-<i>x</i>)(Na) _<i>x</i> (ClO₄)₃ exhibits exceptional thermal stability, outperforming its ternary perovskite prototypes, and the prepared (H₂dabco)(NH₄)_(1-<i>x</i>)Ag _<i>x</i> (ClO₄)₃ manifests energy-safety optimization as elevated energy levels with improved mechanical sensitivity. This work not only exploits perovskite solid solutions as a novel class of energetic materials with promising properties but also provides a means for controllably synthesizing perovskite solid solutions for versatile advanced applications.