The phase transitions occurring during calcination of flame-made calcium phosphates with Ca/P ratios between 1.00 and 1.54 were investigated by thermal analysis and powder X-ray diffraction from room temperature to 1350 degrees C. The as-prepared samples were amorphous and crystallized into metastable, low-temperature alpha(LT) polymorphs of Ca-3(PO4)(2) (TCP) and Ca2P2O7 (CPP) between 600 and 700 degrees C, depending on the Ca/P ratio. The enthalpy changes during crystallization amounted to 26.1 and 58.5 J/g for TCP and CPP, respectively. The metastable alpha(LT) TCP and CPP phases were at first transformed into stable beta polymorphs between 870 and 950 degrees C and, later, between 1140 and 1200 degrees C, into high-ternperature alpha phases. The enthalpy changes during these processes were small and lay in the range of 6-11 J/g. The composition of the eutectic formed ill the system alpha-(TCP-CPP) was determined from the Tamman triangle, the melting enthalpy amounted to 197 J/g and the molar eutectic composition was 0.68 TCP and 0.32 CPP. The use of DSC analyses allowed to determine the composition of the precursor mixture during flame-made process which resulted in the synthesis of pure TCP amorphous phase. (c) 2007 Elsevier B.V. All rights reserved.