Sustainable cooling and thermal energy storage solutions based on long chain alkylammonium halide salts with solid-to-solid phase transition

Thermomaterials are compounds with substantial thermal changes associated with solid-to-solid phase transitions. These materials could play an important role in environmentally friendly alternative refrigerants and thermal energy storage. Decoding the structural origins of the high entropy solid-solid phase transitions is an ongoing challenge of the field. Promising thermomaterials are those based on long chain alkylammonium halide salts, due to their large, reversible phase transition near ambient temperature. This proposal will examine key materials, (C10H21NH3)Cl, (C10H21NH3)(BF4) etc., by conducting single crystal and powder synchrotron-based diffraction measurements in situ with variable temperature and pressure. We will combine this data with thermodynamic parameters obtained from variable temperature and variable pressure differential scanning calorimetry. These studies will offer essential insights on the key structure mechanisms that underpin the solid-solid transitions.