Excess heat capacity and entropy of mixing along the hydroxyapatite-chlorapatite and hydroxyapatite-fluorapatite binaries.

ABSTRACT: The heat capacity, C _p, of synthetic hydroxyapatite [Ca₅(PO₄)₃OH-OH-Ap], as well as of ten compositions along the OH-Ap-chlorapatite (Cl-Ap) join and 12 compositions along the OH-Ap-fluorapatite (F-Ap) join have been measured using relaxation calorimetry (heat capacity option of the Physical Properties Measurement System-PPMS) and differential scanning calorimetry (DSC) in the temperature range of 5-764 K. Apatites along the Cl-OH and F-OH joins were synthesized at 1100 °C and 300 MPa in an internally heated gas pressure vessel via an exchange process between synthetic fluorapatite or chlorapatite crystals (200-500 μm size) and a series of Ca(OH)₂-H₂O solutions with specific compositions and amounts relative to the st

SUBMITTER: Dachs E 

PROVIDER: S-EPMC8553719 | biostudies-literature | 2021

REPOSITORIES: biostudies-literature