Experimental evidences of ferromagnetism in undoped monoclinic zirconia

Abstract

Mixed magnetic feature of paramagnetism and ferromagnetism at room temperature has been observed in annealed powders of nanocrystalline zirconia within a temperature range of 650 °C to 1050 °C. The abundant defect states such as, oxygen vacancies and clusters are originated during the synthesis process. The long range ferromagnetism in nanocrystalline ZrO2 is also due to exchange interaction between the various charge state of oxygen vacancies present at the surface or bulk of the nanostructure and the reduced Zr 4d ions, which leads to the creation of bound magnetic polaron at the defect area in the system. It is also observed that both the zero field curve (ZFC) and field cooled (FC) curve runs simultaneously from room temperature to 50 K without having any significant change in irreversibility temperature.