High-temperature evaporation of lanthanum and praseodymium silicides

Thermodynamic descriptions of the light rare‐earth elements in silicon carbide ceramics

“…As suggested by Kim et al, due to the confliction with other thermodynamic properties, the calculated results are smaller than those determined by Esin et al and Batalin et al The standard formation enthalpies for the La‐Si compounds compared with the work of Meschel and Kleppa and those published on Materials Project are shown in Figure F, which are in reasonable agreement. However, the standard formation enthalpies of LaSi 2 and LaSi estimated from Knudsen mass‐spectrometry measurements are not considered during optimization . Figure G presents the calculated standard entropies, which are agree with the work of Bolgar et al, especially for those of La 5 Si 3 , La 3 Si 2 , and La 5 Si 4 .…”

“…Calculated La‐Si phase diagram together with thermodynamic properties: (A) La‐Si phase diagram; (B) heat capacities of La 5 Si 3 , La 3 Si 2 , La 5 Si 4 , LaSi, and LaSi 2 by adiabatic calorimetry; (C) enthalpy increments (H T ‐H 298 ) of these compounds by high‐temperature calorimetry (HTC); (D) integral enthalpy of mixing of liquid by HTC; (E) partial enthalpy of mixing of liquid by HTC; (F) standard enthalpy of formation by direct reaction calorimetry, mass‐spectrometry, first‐principles calculations, Miedema' model, and electromotive force method; (G) standard entropy by adiabatic calorimetry; (H) activity of Si in La‐Si solution by Hilderbrand‐Mott equation [Color figure can be viewed at wileyonlinelibrary.com]…”

“…Calculated Pr‐Si phase diagram together with thermodynamic properties: (A) Pr‐Si phase diagram; (B) heat capacities of Pr 5 Si 3 , Pr 5 Si 4 , PrSi, α‐Pr 5 Si 9 , and β‐Pr 5 Si 9 by adiabatic calorimetry; (C) enthalpy increments (H T ‐H 298 ) of Pr 5 Si 3 , Pr 5 Si 4 , PrSi, and Pr 5 Si 9 by high‐temperature calorimetry; (D) standard enthalpy of formation direct reaction calorimetry and mass‐spectrometry; (E) standard entropy by adiabatic calorimetry [Color figure can be viewed at wileyonlinelibrary.com]…”

“…The formation enthalpies published by Materials Project were considered as well . Gordienko and Fenochka used Knudsen mass‐spectrometry measurements at 1800‐2000 K to detect the standard atomizing enthalpy by an atomization reaction: LnSi n (c)→Ln(gas) + nSi(gas). However, considerable experimental uncertainties (3‐18 kJ) were reported for their results.…”

“…Gordienko and Fenochka estimated the standard formation enthalpies of the PrSi and Pr 5 Si 9 phases using Knudsen mass‐spectrometry. However, the results were much more positive than those of Meshel and Kleppa, which were determined by DRC.…”