Pressure dependent structural changes and predicted electrical polarization in perovskite RMnO₃

Prior studies have explored structural transformations in perovskite compounds under pressure, but specific effects vary with ionic size and coordination. Established research shows that high-pressure x-ray diffraction can track lattice strain and distortion. However, the interplay between Jahn-Teller distortions and pressure-induced polarization remains unclear. This gap motivated the current work to investigate how different rare-earth ions affect structural and vibrational responses. No prior work had resolved how phonon behavior correlates with Mn-O bond changes in LuMnO3. It was already known that DyMnO3 and HoMnO3 exhibit lattice strain under pressure. Yet, the stability of Jahn-Teller distortions in these systems was not fully understood. This study addresses how pressure alters structural and vibrational properties in RMnO3 compounds.

This study aimed to examine structural and vibrational responses in RMnO3 perovskites under pressure. The specific problem is understanding how different R ions influence lattice strain and Jahn-Teller distortions. The motivation comes from the need to correlate structural changes with electrical polarization. The researchers propose that pressure could be used to control polarization in these materials. They also seek to compare DyMnO3, HoMnO3, and LuMnO3 under pressure. The study focuses on how Mn-O bond distortions and phonon behavior vary with R-ion size. The authors suggest that structural changes in LuMnO3 may be linked to polarization optimization. This work addresses a gap in understanding how pressure affects perovskite phase stability.

The study used high-pressure x-ray diffraction to track structural changes in DyMnO3, HoMnO3, and LuMnO3. Infrared spectroscopy was employed to monitor phonon behavior at different pressures. Density functional theory calculations were performed to model phase stability up to 10 GPa. The x-ray measurements revealed lattice strain and Jahn-Teller distortions in DyMnO3 and HoMnO3. In LuMnO3, Mn-O bond distortions were observed between 4 and 8 GPa. The infrared data showed a phonon near 390 cm(-1) that softened in LuMnO3 under pressure. Theoretical simulations supported the structural changes observed in LuMnO3. The methods combined experimental and computational approaches to analyze pressure effects.

DyMnO3 and HoMnO3 showed large lattice strain under pressure, with stable Jahn-Teller distortions. LuMnO3 exhibited Mn-O bond distortions between 4 and 8 GPa, with a broad minimum in Jahn-Teller distortion. Infrared measurements revealed a phonon near 390 cm(-1) that softened in LuMnO3 between 4 and 8 GPa. This phonon softened in the bond distortion region and then hardened at higher pressures. By contrast, phonons in DyMnO3 and HoMnO3 continuously hardened with increasing pressure. Density functional theory simulations confirmed E-phase LuMnO3 as the most stable phase up to 10 GPa. The results suggest that structural changes in LuMnO3 could be used to optimize electric polarization. These findings highlight the role of R-ion size in determining structural and vibrational responses.

The authors propose that structural changes in LuMnO3 under pressure may be used to optimize electric polarization. They suggest that pressure-induced strain could control polarization in perovskite materials. The study shows that DyMnO3 and HoMnO3 exhibit stable Jahn-Teller distortions under pressure. In contrast, LuMnO3 shows distinct Mn-O bond distortions between 4 and 8 GPa. The phonon near 390 cm(-1) in LuMnO3 softens in this pressure range, indicating structural changes. Theoretical simulations support the stability of E-phase LuMnO3 up to 10 GPa. The findings suggest that R-ion size influences structural and vibrational responses. These results may guide future studies on pressure-induced polarization in perovskites.