Energetics of charge order transition in image

The transition from the high-temperature pseudocubic form of the perovskite manganites image, image, 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 image with a maximum at the apparent image is observed for image, the other two compositions reveal typical image-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.