Solid-solid phase transition of (1-C14H29NH3)2ZnCl4 in nanopores of silica gel for thermal energy storage

Latent heat storage performance of a layered perovskite-type compound, 1-C₁₄H₂₉NH₃)₂ZnCl₄ (C₁₄Zn), embedded in a series of silica gel (SG) with pore sizes of d=15-200 nm is investigated using differential scanning calorimetry (DSC), and powder X-ray diffractions (XRD). C₁₄Zn in the nanopores of silica gel shows size-dependent phase transition temperature, enthalpy change and supercooling. They have a stable transition temperature and heat capacity at each size in a short-term thermal cycling. Similar Xray diffraction patterns are observed for the nano-sized and the bulk C₁₄Zn. The encapsulation of a phase change material in nanopores is a new way of tuning its thermal energy storage properties for a wider range of temperature regulation.