First‐Principles Calculations and Thermodynamic Modeling of the Al₂O₃–Nd₂O₃ System

Abstract

Using first‐principles calculations, the enthalpies of formation of NdAlO3 and Nd4Al2O9 from neodymia and alumina are predicted to be −41.1 and −104.5 kJ/mol‐form, respectively, and Nd4Al2O9 is predicted to be a stable compound at all temperatures up to its peritectic decomposition temperature. In the case of NdAlO3, where reported experimental enthalpies of formation differ, our predicted value is used to determine which experimental value is more accurate. The enthalpies of formation calculated by the first‐principles method are combined with experimental phase equilibria to evaluate the Gibbs energies of phases in the Al2O3–Nd2O3 system. The resulting Gibbs energy functions are compared with previous modelings of the system and are shown to be an improvement as more thermochemical data have been included. The combined first‐principles/thermodynamic modeling approach employed in the current work shows promise in enabling the evaluation of important ceramic systems in which experimental thermochemical data are scarce.

First-Principles Calculations and CALPHAD Modeling of Thermodynamics

“…Calculated enthalpies of formation can significantly enhance the robustness of thermodynamic modeling and have been used in the following systems: Al-Sr, [100] Al-Ca, [101] Ni-Mo, [102] Al-Mg, [103] Co-Y, [104] Zn-Zr, [105] Mg-Al-Ca, [106] Ca-Mg, [107] Mg-Sr and Ca-Mg-Sr, [108] Hf-Si-O, [109] Al 2 O 3 -Nd 2 O 3 , [110] and Cu-Si. [111] In most cases, the first-principles calculations provided enthalpy of formation that was not previoulsy available in the literature.…”

First‐Principles Thermochemistry and Thermodynamic Modeling of the Al2O3–Nd2O3–SiO2–Y2O3 Pseudoquaternary System

“…To construct a CALPHAD model for the Al 2 O 3 -Nd 2 O 3 -SiO 2 -Y 2 O 3 system, the component pseudobinary and pseudoternary subsystems must be modeled. This section begins with descriptions of the modeling of two systems taken from previous work, Al 2 (1) Al 2 O 3 -Nd 2 O 3 The Al 2 O 3 -Nd 2 O 3 system has recently been remodeled, 9 incorporating first-principles calculations and experimental data. Another modeling was reported a year earlier, 11 using only experimental data and information from the ZrO 2 -Nd 2 O 3 -Al 2 O 3 system.…”

“…Another modeling was reported a year earlier, 11 using only experimental data and information from the ZrO 2 -Nd 2 O 3 -Al 2 O 3 system. The modeling with first-principles calculations 9 is employed in the current work as more thermochemical data for the pseudobinary compounds are included. A review of the experimental data for the system can be found in Saal et al 9 (2) Al 2 O 3 -SiO 2 -Y 2 O 3 The Al 2 O 3 -SiO 2 -Y 2 O 3 system has been modeled following an extensive literature review and new experimental data.…”

Dielectric Relaxation, Modulus Behaviour and Conduction Mechanism in NdAlO3 Ceramics

“…15 The anti-Stokes white emission in NAO nanocrystal at ambient atmosphere was quite recently observed by Strek et al 16 Van der Laan et al 17,18 have studied the heat capacity of NAO from 0 K to 900 K. Using first-principles calculations, the enthalpy of formation for NAO has been predicted to be À41.1 kJ/mol-form. 19 However, to the best of our knowledge, a detailed investigation regarding the systematic study of the dielectric relaxation and conduction mechanism of NAO has not been performed. Recently, we have investigated the frequency-dependent dielectric behaviour of SmAlO 3 (SAO) at various temperatures, 20 because SAO exhibits high dielectric constant ($20.4) and is used as dielectric resonators and pads for microwave components.…”