The superexchange interaction occurring in CeO2 causes room-temperature ferromagnetism, The M-H loops of CeO2 before and after UV exposure at room temperature are given in Fig 7b . The increase of oxygen vacancies on being exposed to UV radiation has been reported to increase saturation magnetization. The oxidation state of Ce in ceO2 is +4, with one Ce atom being attached to two oxygen atoms, The oxygen vacancy creates two lone pairs of electrons in the 2p orbital of oxygen. These are unpaired electrons trapped in oxygen vacancies which is a paramagnetic defect having excess spins. Each of these electrons moves from tetragonal ceria into the 4f orbital of two separate Ce atoms in the cubic ceria on being excited by UV light forming two Ce +3 ions by reduction, paramagnetic in nature with unpaired f electrons. The new electron has a parallel spin direction with the previously existent electron in the 4f orbital. An exchange of the two electrons in two Ce 4 f orbitals takes place due to the 90 o Ce-O-Ce bond angle and is known as superexchange which results in magnetism. The high Ce +3 ion and oxygen storage capacity which includes not only storing oxygen but also releasing it to create vacancies in Ceria creates distortion in the lattice as well as in the electronic structure .