Thermodynamics Research Center / ThermoML | Thermochimica Acta

Isomorphism and phase diagram of Pb5(PO4)3F-Pb5(PO4)3Cl system

Knyazev, A. V.[Aleksandr V.], Chernorukov, N. G., Bulanov, E. N.
Thermochim. Acta 2011, 513, 1-2, 112-8
ABSTRACT
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 hightemperature 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)3FPb5( 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)3FPb5( 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.
Compounds
# Formula Name
1 Pb lead
2 P phosphorus
3 F2 fluorine
4 O2 oxygen
5 Cl2 chlorine
6 FO12P3Pb5 Lead fluoride phosphate (Pb5F(PO4)3)
7 ClO12P3Pb5 Lead chloride phosphate (Pb5Cl(PO4)3)
Datasets
The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type Compound-# Property Variable Constraint Phase Method #Points
  • POMD
  • 6
  • Triple point temperature, K ; Crystal 2
  • Crystal 2
  • Crystal 1
  • Air at 1 atmosphere
  • DTA
  • 1
  • POMD
  • 6
  • Triple point temperature, K ; Crystal 1
  • Crystal 1
  • Liquid
  • Air at 1 atmosphere
  • DTA
  • 1
  • POMD
  • 6
  • Mass density, kg/m3 ; Crystal 2
  • Temperature, K; Crystal 2
  • Pressure, kPa; Crystal 2
  • Crystal 2
  • X-ray diffraction
  • 10
  • POMD
  • 7
  • Triple point temperature, K ; Crystal 2
  • Crystal 2
  • Crystal 1
  • Air at 1 atmosphere
  • DTA
  • 1
  • POMD
  • 7
  • Triple point temperature, K ; Crystal 1
  • Crystal 1
  • Liquid
  • Air at 1 atmosphere
  • DTA
  • 1
  • POMD
  • 7
  • Mass density, kg/m3 ; Crystal 2
  • Temperature, K; Crystal 2
  • Pressure, kPa; Crystal 2
  • Crystal 2
  • X-ray diffraction
  • 9
  • RXND
  • 6
  • 1
  • 2
  • 3
  • 4
  • Molar enthalpy of reaction, kJ/mol
  • Solution calorimetry
  • 1
  • RXND
  • 7
  • 1
  • 2
  • 5
  • 4
  • Molar enthalpy of reaction, kJ/mol
  • Solution calorimetry
  • 1