Role of non-magnetic dopants on the room temperature ferromagnetism and optical properties of BaSnO3 perovskite

Abstract

In this study, room temperature ferromagnetism was induced in diamagnetic BaSnO3 ceramic through light doping with non-magnetic elements composed of Tl, Bi, Ce, Zr and Y. Pure BaSnO3 powders were synthesized via a modified sol gel Pechini method. XRD measurements and Rietveld refinement confirmed the formation of cubic BaSnO3 structure with effective incorporation of dopants into BaSnO3 host lattice. A relation between the ionic radius and valence states of the dopants with the occupation sites and defect states in BaSnO3 crystal lattice was noticed. The SEM micrographs of doped BaSnO3 showed an improvement in the grain shape accompanied by grain size reduction, as compared to the characteristics of pure BaSnO3. EDX analysis verified the presence of Ba, Sn and O as main elements besides Tl, Bi, Ce, Zr or Y as dopants in BaSnO3 samples. From Kubelka-Munk plots, the dopants prompted red and blue shifts in the optical band gap of BaSnO3 (3.22 eV) range from 0.04 to 0.06 eV. As based on photoluminescence (PL) measurements, pure and doped BaSnO3 revealed luminescence peaks in the near infrared and visible regions. Interestingly, Tl, Bi, Ce, Zr and Y as non-magnetic dopants stimulated remarkable room temperature ferromagnetism in BaSnO3 structure. The hysteresis loops shape, saturation magnetization (Ms) and coercivity (Hc) value were found to depend on dopant type. Among all dopants, the BaSn0.98Zr0.02O3 composition revealed perfect room temperature ferromagnetism with the highest Ms and Hc values of 0.106 emu/g and 3212 Oe respectively, which draws attention of utilizing it as spintronic material. A correlation between the grain size, oxygen vacancies, ionic radii, oxidation state of dopants and the emerged ferromagnetism was discussed in details.