Defect controlled room temperature ferromagnetism in Co-doped barium titanatenanocrystals

Abstract

Defect mediated high temperature ferromagnetism in oxide nanocrystallites is the centralfeature of this work. Here, we report the development of room temperature ferromagnetismin nanosized Co-doped barium titanate particles with a size of around 14 nm,synthesized by a solvothermal drying method. A combination of x-ray diffraction withstate-of-the-art electron microscopy techniques confirms the intrinsic doping of Co intoBaTiO3. The development of the room temperature ferromagnetism was tracked down to thedifferent donor defects, namely hydroxyl groups at the oxygen site () and oxygen vacancies (), and their relative concentrations at the surface and the core of the nanocrystal, whichcould be controlled by post-synthesis drying and thermal treatments.