Magnetic investigation of Mn ions in La,Mn : SrTiO3

Electron paramagnetic resonance (EPR) and static magnetic susceptibility me asurements were carried out on lanthanum-manganese substituted (up to 10 mo l%) strontium titanate polycrystalline samples. X-ray diffraction (XRD) ana lysis revealed in each sample a single cubic perovskite phase with a differ ent lattice parameter. Only weak and narrow EPR signals from a small fracti on of Mn2+ and Mn4+ ions were observed when the La and Mn content did not e xceed 5 mol%, indicating the nearly complete stabilisation of the Mn3+ oxid ation state. Heavily substituted samples showed another EPR signal, very br oad and with intensity and resonance field strongly temperature dependent. For these samples, a complex dynamics of Mn3+ stabilisation is suggested, s upported by micro-Raman data. (C) 2000 Published by Elsevier Science Ltd.