Interfacial induction sustained ferromagnetism - from solution chemistry to ceramics

Abstract

This PhD research focuses on the development of magnetic ceramic materials and membranes by means of solution chemistry. Lanthanum strontium cobalt oxide composite, (1-x)La2O3/xSrO/Co3O4, was fabricated via synthesis of metallo-organic chelating gels and their magnetic properties were investigated. This study had found that such a heterogeneous tri-oxide composite manifests room temperature ferromagnetism in contrast to its homogeneous counterparts, which has a curie temperature far below room temperature. It was found that this ferromagnetism is due to an intricate interfacial induction between SrO and spinel Co3O4 nano domains in which La2O3 displays a special enhancement effect on its magnetism. Further studies were extended to neodymium strontium cobalt oxide and similar induction effect was observed. Another material of interest was M-TiO2, where M stands for magnetic nano-wedges such as magnetic oxides. A revamped sol-gel coating technique was coined for accomplishing M-TiO2 thin films, and the origin of its ferromagnetism was explored.