Thermodynamic Assessment of P₂O₅

Abstract

All the thermodynamic property data and phase diagrams related to solid and liquid P2O5 were critically evaluated and optimized to obtain the best set of Gibbs energies for all phases. Confusion in literature data due to the very sluggish nature of the reactions involving P2O5 was resolved. The Gibbs energies of O‐ and O′‐P2O5 were evaluated for the first time based on the phase stability against gas. The Gibbs energy of liquid H‐P2O5, liquid O‐P2O5, and liquid O′‐P2O5 were also properly evaluated for the first time based on the metastable and stable vapor pressures. The calculated triple points of H‐P2O5, O‐P2O5, and O′‐P2O5 are 420°C and 4.600 bar, 575°C and 0.805 bar, and 580°C and 0.774 bar, respectively. The calculated polymorphic transition point between O‐P2O5 and O′‐P2O5 is located at 65°C and 0.001 bar.

Phosphorus Equilibrium Between Liquid Iron and CaO-SiO2-MgO-Al2O3-FeO-P2O5 Slag Part 1: Literature Review, Methodology, and BOF Slags

“…The activity coefficient was increased by silica and decreased by basic oxides such as CaO and MgO. [7] Recently, in 2012, Jung and Hudon [8] reassessed the standard enthalpies of formation, entropies, and heat capacity of stable liquid P 2 O 5 based on measured data. DH and DS-for the reaction represented in Eq.…”

Thermodynamic Database of P2O5-containing Oxide Systems for the Dephosphorization Process in Steelmaking

“…One should be therefore careful to take the thermodynamic data of P 2 O 5 from these sources. A discussion on the thermodynamic properties of P 2 O 5 can be found elsewhere [3].…”

“…In the present study, optimized binary liquid model [42]. The Gibbs energy of pure liquid P 2 O 5 of Iwase et al [42] was corrected according to the new P 2 O 5 Gibbs energy by Jung and Hudon [3] to ensure a thermodynamically consistent database development. Brought to you by | University of Queensland -UQ Library Authenticated Download Date | 6/17/15 5:11 PM parameters (interaction parameters between P 2 O 5 and other oxide components in liquid slag), which can reproduce all thermodynamic properties and phase diagram in the binary systems, were used to predict the dephosphorization of multi-component slags.…”

“…Consequently, a critical thermodynamic evaluation of pure P 2 O 5 was properly carried out for the first time using all available equilibration data for gaseous, solid and liquid P 2 O 5 [3]. Interestingly, the well-accepted Gibbs energy of formation (DG f o ) of liquid P 2 O 5 from Turkdogan and Pearson in 1953 [4] is not consistent with the experimental phase diagram data of P 2 O 5 : In the present study, the new DG f o of P 2 O 5 (l) is evaluated based on all available thermodynamic data of the P 2 O 5 system.…”

(Ti,Cr)C Synthesized <i>In Situ</i> by Spark Plasma Sintering of TiC/Cr₃C₂ Powder Mixtures

“…Figures 1(a)(b)(c) are the X-ray diffraction patterns illustrating the phase evolution. Here, (a) is the pattern for the Ti-Cr alloy raw powder, (b) is the pattern after milling for 10 h with the addition of graphite, (c) is the pattern after annealing sample (b) at 1200°C for 2 h. Ti-Cr alloy powder was composed of a series of Ti-Cr intermetallic compounds (Ti 4 Cr, TiCr 2 , and Ti 0.95 Cr 0.05 ) and pure Ti (See Fig. 1(a)).…”