Structural stability of the robust GdYTi ₂ O ₇ pyrochlore under high pressure

Abstract Complex ceramics with pyrochlore (A 2 B 2 O 7 ) and defect‐fluorite ((A, B) 4 O 7 ) type structures experience structural modifications under high pressure. Here, we used mechanical milling and sintering followed by compression in diamond anvil cell to determine the high‐pressure behavior using in‐situ synchrotron diffraction. Raman spectroscopy and X‐ray diffraction at ambient pressure confirm the pyrochlore phase of as‐prepared GdYTi 2 O 7 ceramic. In‐situ high‐pressure experiments reveal no structural phase transition in GdYTi 2 O 7 pyrochlore up to approximately 50 GPa. The variation in the x positional coordinate of O 48f oxygen and cation–anion bond lengths shows that disordering occurs at high pressure above ∼43 GPa. The Rietveld refinement results indicate the pyrochlore phase of GdYTi 2 O 7 ceramic at the highest pressure of ∼50 GPa. Compared to Y 2 Ti 2 O 7 , the equal substitution of Y 3+ and Gd 3+ at the A‐site increases phase stability at high pressures. The experimental results indicate that mainly cation disordering occurs with increasing pressure, and lower compressibility of < Ti–O 48f > bonds should play a significant role in the robustness of GdYTi 2 O 7 pyrochlore to sustain pyrochlore structure up to very high pressures. DFT‐derived cation–anion bond lengths and bulk modulus value agree with the experimental results in supporting the robustness of the GdYTi 2 O 7 pyrochlore.