Study of Phase Transformations on Nanocrystalline (La,Sr)(Mn,Fe)O3 System by High-Pressure Mossbauer Spectroscopy

We report here the pressure dependent 57Fe Mossbauer studies on the nanocrystalline La0.8Sr0.2(Mn0.8Fe0.2)O3 system up to 10 GPa using diamond anvil cell. At ambient pressure, iron is present as Fe3+ and Fe4+ in two different environments. Pressure seems to affect the higher symmetry site of Fe4+ only, while the octahedral site containing Fe3+ remains almost unaffected. Phase transformations are observed at pressures 0.52GPa and 3.7 GPa respectively. A sudden increase in the isomer shift at 0.52GPa is related to the reduction of Fe4+ ions while at 3.7GPa, a structural transition is observed with a sudden drop in isomer shift indicating that the Fe3+ ions are in identical environment. Quadrupole splitting increases continuously with pressure up to 10 GPa.