First-Principles Calculations of Formation Pathways for Ce₂Si₂O₇ Oxide Particles at High Temperatures

Fine-sized oxide particles are often used to improve the mechanical properties and service life of materials. Particularly, rare earth-silicate particles have high deformability and promising applications in metallic materials and ceramic coatings. To study the formation of rare earth-silicate particles and control their physical characteristics, we apply first-principles calculations and investigate the nucleation mechanism of Ce₂Si₂O₇ particles at the atomic scale. The estimated thermodynamic properties of (Ce₂Si₂O₇)_n (n = 1 – 4) agree reasonably well with the experimental data, indicating that the first-principles calculation is reliable. Furthermore, the potential of a preformed nuclear phase for Ce₂Si₂O₇ particles is thermodynamically demonstrated. Four formation pathways of Ce₂Si₂O₇ particles are proposed and discussed. Based on thermodynamic principles, the most probable formation pathway is [Ce]+[Si]+[O]→(Ce₂Si₂O₇)_n→Ce₂Si₂O_7(s), and another formation pathway is considered the least likely, (SiO₂)_n+(Ce₂O₃)_n→(Ce₂Si₂O₇)_n→Ce₂Si₂O_7(s).