Determination of the individual specific heat capacities of solids from multi-component powder mixtures and polymorphic mixtures

This study describes a method to determine the specific heat capacities of individual solids from multi-component solid mixtures. To achieve this end, powder X-ray diffraction measurements are used to provide information on the number and identity of constituents as well as their compositions while calorimetry measurements give the specific heat capacities of the bulk solid mixtures. The method is applied to investigate three different solid mixture systems, namely (i) ternary organic mixtures containing α-glycine, α-lactose monohydrate, and paracetamol; (ii) ternary inorganic mixtures containing calcium fluoride, titanium nitride, and tungsten carbide; and (iii) polymorphic mixtures of α- and γ-glycine. All systems are investigated at 298.15 K and at atmospheric pressure. The results show that the specific heat capacities of individual solids determined from multi-component solid mixtures are in good agreement with those directly determined from pure solid compounds.