Study of phase transition on nanocrystalline (La, Sr)(Mn, Fe)O system using high-pressure M?ssbauer spectroscopy and high-pressure X-ray diffraction

摘要

Pressure-induced structural changes on nano-crystalline La0.8Sr0.2Mn0.8Fe0.2O3 were studied using high-pressure M?ssbauer spectroscopy and high-pressure X-ray diffraction. M?ssbauer measurements up to 10 GPa showed first order transition at 0.52 GPa indicating transformation of Fe4 + to high spin Fe3 + , followed by another subtle transition at 3.7 GPa due to the convergence of two different configurations of Fe into one. High-pressure X-ray diffraction measurements carried up to 4.3 GPa showed similar results at 0.6 GPa as well as 3.6 GPa. Attempts were made to explain the changes at 0.6 GPa by reorientation of grain/grain boundaries due to uniaxial stress generated on the application of pressure. Similarly variation at 3.6 GPa can be explained by orthorhombic to monoclinic transition.