Structure and Properties Impacting Ferroelectricity in Sn₂P₂S₆

Sn₂P₂S₆ samples prepare under various conditions including chemical vapor transport and the Bridgman method exhibit marked variations in optical and dielectric properties. To understand the origin of these changes, detailed measurements of the thermal properties by specific heat methods are combined with structural measurements on multiple length scales. We link critical temperature-dependent structural changes with enhanced electronic properties.