Thermodynamic description of the Gd2O3-Y2O3-HfO2 and La2O3-Y2O3-HfO2 systems at high temperatures

Vaporization and thermodynamics of ceramics in the Sm2O3‐Y2O3‐HfO2 system

“…The results obtained in the present study by the Knudsen effusion mass spectrometric method at 2373 K were optimized using the Barker‐Guggenheim generalized theory of associated solutions (GLTAS), which was applied earlier for modeling of the thermodynamic properties in the La 2 O 3 ‐Y 2 O 3 ‐HfO 2 and Gd 2 O 3 ‐Y 2 O 3 ‐HfO 2 systems . As was already discussed, the activities of components in these systems could be considered as temperature independent, and therefore in all these studies the excess chemical potentials of components were calculated from the measured component activities at a uniform temperature of 2500 K and optimization was performed using the same lattice basic model.…”

Mass spectrometric study and modeling of the thermodynamic properties in the Gd2O3‐ZrO2‐HfO2 system at high temperatures

“…The integral thermodynamic functions in a ternary system can be derived from the activity data for only one component using the Generalized Lattice Theory of Associated Solutions (GLTAS) also known as the Barker‐Guggenheim approach 29,30 . This approach was successfully applied to optimization and analysis of the results of investigation of a series of binary and ternary systems including hafnate systems 10,14,15 . Modeling of the thermodynamic properties of the melts and solid solutions is based on interpolation of the experimental dependences of the chemical potentials μ i or the Gibbs energies Δ G on the composition.…”

“…In the modeling of the essentially nonideal Gd 2 O 3 -ZrO 2 -HfO 2 system, the experimental data on gadolinium oxide alone (Table 5) are insufficient for unambiguous optimization of all η AB μν values. Therefore, the values of the energy parameters, which had been fixed already in our earlier studies, 10,15,31 were substituted into system (14) to reduce the number of variables.…”

“…A search for new compositions of the zirconia‐hafnia ceramics stabilized by rare earth oxides is interesting, first of all, in view of the advantages they may provide when used as materials for thermal barrier coatings 1–6 and for casting moulds and cores in the production of gas turbine engine blades 7–9 . Investigation of the thermodynamic properties of the Gd 2 O 3 ‐ZrO 2 ‐HfO 2 ceramics in addition to the data obtained earlier for the systems containing yttrium, lanthanum, and samarium oxides as stabilizing components 10–16 will contribute greatly to the thermodynamic database significant for discovery and analysis of compositions with higher operational temperatures and thermal resistance, better durability, and stability of performance. The experimental results were obtained by the Knudsen effusion mass spectrometric method that provides information on the vapor composition over the samples under study and partial pressures of the vapor species thereby allowing the determination of the thermodynamic activities of components in the system.…”

“…obtained earlier for the systems containing yttrium, lanthanum, and samarium oxides as stabilizing components [10][11][12][13][14][15][16] will contribute greatly to the thermodynamic database significant for discovery and analysis of compositions with higher operational temperatures and thermal resistance, better durability, and stability of performance. The experimental results were obtained by the Knudsen effusion mass spectrometric method that provides information on the vapor composition over the samples under study and partial pressures of the vapor species thereby allowing the determination of the thermodynamic activities of components in the system.…”