Neutron diffraction and magnetic properties of La_1-xSr_xCoO₃ nanoparticles

The LaCoO₃, a rhombohedrally distorted perovskite, has attracted considerable attention mainly due to its peculiar properties such as spin-state and metal-insulator transitions with temperature. It is reported that, in contrast to a nonmagnetic insulating ground state of bulk LaCoO₃, the nanoparticle samples exhibit a ferromagnetic (FM) ordering below T_C∼ 85 K. An enhancement in the volume of the unit cell may play a crucial role for the appearance of FM ordering in nanoparticle samples. However, the nature/origin of the FM state and spin-state transition has been the subject of debate and boosted new interests in understanding the effect of hole doping by Sr³⁺ substitution at La²⁺ site. Therefore, we study the structural and magnetic properties of La_(1-x)Sr_xCoO₃ nanoparticles (prepared by citric solgel method). By performing the Rietveld refinement of room temperature X-ray diffraction (XRD) data, we confirm the crystalline nature and single phase of all the samples