This paper presents two distinct methods for the determination of the solid-solid transition temperature (Ttr) separating the temperature ranges of stability of two crystallographic forms, hereafter called morphs, of a same substance. The first method, based on thermodynamic calculations, consists in determining Ttr as the temperature at which the Gibbs free energies of the two morphs are equal to each other.
Herman, C., Leyssens, T., haut, b., Halloin, V., & Vermylen, V. (2011). Towards an accurate and precise determination of the solid-solid transition temperature of enantiotropic systems. The Journal of Chemical Thermodynamics, 43(5), 677-682. https://doi.org/10.1016/j.jct.2010.12.006 (Original work published 2011)