Compounds of composition Pb5(PO4)3FxCl1-x(0 ≤ x ≤ 1), which are synthetic analogues of minerals pyromorphite, flourapatite, and endlichite, were synthesized for the first time by high-temperature solid phase reactions. X-ray diffraction and IR spectroscopy were used to determine the structure of the compounds and revealed complete miscibility in the solid phase of the Pb5(PO4)3F-Pb5(PO4)3Cl binary system. Adiabatic reaction calorimetry was used to measure standard enthalpies of mixing and formation and show that the regular solutions model is applicable to the Pb5(PO4)3F-Pb5(PO4)3Cl system. Differential thermal analysis in tandem with high-temperature X-ray diffraction were used to study the phase diagram and characterize phase transitions. © 2010 Elsevier B.V. All rights reserved.
Knyazev, A. V., Chernorukov, N. G., & Bulanov, E. N. (2011). Isomorphism and phase diagram of Pb5(PO4)3F-Pb5(PO4)3Cl system. Thermochimica Acta, 513(1–2), 112–118. https://doi.org/10.1016/j.tca.2010.11.020