Experimental and theoretical study on the effect of different rare-earth oxides on the high-temperature stability of SiO₂ glass at 1973K

The effect of different rare-earth oxides additives (La₂O₃, Nd₂O₃, Y₂O₃, Sm₂O₃, Yb₂O₃ and Lu₂O₃) on the stability of SiO₂ glass at 1973 K was systematically studied employing volatility test and first-principles calculations. Both experimental and theoretical results show that the introduction of rare-earth oxides plays an active role in developing the stability of SiO₂ glass at 1973 K due to the presence of Re₂Si₂O₇ (Re= La, Nd, Y, Sm, Yb, Lu) phase. SiO₂ glass samples doped with rare-earth oxide owning smaller cationic radius show better stability at 1973 K. Re atoms in Re₂Si₂O₇ can diffuse into SiO₂, which tends to occupy the interstitial site of SiO₂ network. The influence of various interstitial Re atoms on SiO₂ network are different and the inLu-SiO₂ structure is the most stable. Meanwhile, the diffusion of Re atoms enhances the interface bonding between SiO₂ (0 1 0) and inRe-SiO₂ (1 1 2) and the inLu-SiO₂ (1 1 2)/SiO₂ (0 1 0) interface owns the highest binding energy, which is profitable to develop the thermal stability of SiO₂ glass at 1973 K.