The phase diagrams of four binary systems (C10H21NH3)2CoCl4−(C16H33NH3)2CoCl4, (C12H25NH3)2CoCl4−(C16H33NH3)2CoCl4, (C10H21NH3)2ZnCl4−(C16H33NH3)2ZnCl4 and (C12H25NH3)2ZnCl4−(C16H33NH3)2ZnCl4 were investigated by means of DSC. These six compounds and their binary mixtures can retain energies between 74 and 115 J/g during solid-state transformations at temperatures between 70 and 105°C, and they are therefore being conside...