The formation of fluid inclusions is often an anathema for many applications of crystallized phases. For instance: Active Pharmaceutical Ingredients (solvent content above ICH guidelines), second harmonic generation (yield in the intensity of the secondary beam and chemical degradation of the SHG material), energetic material (shock sensitivity), solid oxidizers (loss of the rocket booster power) [1-2], etc…

This study focuses on two organic compounds: dicumyl peroxide [3-4] and benzoyl peroxide. Besides the obvious similarity in their formulas and the propensity of dissolved CO₂ to induce the formation of fluid Inclusions [5], these fluid inclusions present different: thermal behaviors, shapes and frequencies which will be detailed. They reveal different formation and relaxation mechanisms. Further extension of these findings to other peroxides are currently under investigations.

1-Evidence of Two Types of Fluid Inclusions in Single Crystals; E. Bobo, B. Lefez, M-C. Caumon, S. Petit, and G. Coquerel; CrystEngComm. 2016, 18, 5287–5295

2- Growth rate dispersion at single crystal level E. Bobo, S. Petit, G. Coquerel; Chemical Engineering & Technology, 2015, 38, (6), 1011-1016

3- Formation mechanism of liquid inclusions in dicumyl peroxide crystals; Zhou, J.; Hao, L.; Hao, H.; Ji, X.; Li, J.; Zhou, L. CrystEngComm, 2021, 23, 4214–4228.

4- Behaviors of Gas-Rich Crystalline Fluid Inclusions. L. Salgado-Paredes, F. Faure, G. Coquerel, Crystals, 2025, 15, 740. https://doi.org/10.3390/cryst15080740