Size induced arrest of the room temperature crystallographic structure in nanoparticles of La_0.5Ca_0.5MnO₃

Abstract

We have shown, using high resolution X-ray diffraction studies of nanoparticles, that size reduction can lead to an arrest of the high temperature phase in perovskite materials, which prevents growth of the low temperature phase that needs a specific crystal structure for its stabilization. This has been shown in the context of ∼15 nm diameter nanocrystals of La_0.5Ca_0.5MnO₃, in which the orthorhombic distortion at room temperature freezes in and, as a consequence, the charge order cannot set in and the ferromagnetic state that sets in at higher temperature is stabilized at low temperature.