Energetics of charge order transition in Bi1-xSrxMnO3Bi1-xSrxMnO3

The transition from the high-temperature pseudocubic form of the perovskite manganites Bi1-xSrxMnO3Bi1-xSrxMnO3, x=0.3,0.5,0.8x=0.3,0.5,0.8, to their orthorhombically distorted charge-ordered state is examined. As the experimental probe the measuring of the heat capacity by heat flux DSC incremental method above 300 K and by relaxation method below 300 K is used. While a broad symmetrical transition spanning the temperature interval ΔT∼500K with a maximum at the apparent TCO∼500K is observed for x=0.5x=0.5, the other two compositions reveal typical λλ-shaped peaks often considered as typical for the second order transitions. The total entropy release on heating is interpreted in terms of a simultaneous change of charge, orbital and spin degree of freedom.

Bi1-xSrxMnO3Bi1-xSrxMnO3-heat capacity of charge/orbital and magnetic ordering transition.Figure optionsDownload full-size imageDownload as PowerPoint slide