Probing the Perovskite Oxides: An Optical and Magnetic Study

Ankita Sarkar
School of Material Sciences
Indian Association for the Cultivation of Science, Kolkata

Abstract:

Perovskite oxides (with general structure ABO₃) show unusual property modification due to aliovalent doping. In the first part of the seminar, I plan to discuss regarding the defect and optical properties of Sb doped and hydrogenated BaSnO₃. Both Sb⁺⁵ and hydrogen dopant enhance the optical band gap. Our most crucial finding is the appearance of local vibrational modes due to hydrogenation and the identification of charge states of hydrogen. The existence of intrinsic defects, e.g., oxygen vacancy has been extensively investigated by EPR technique.

In the second part, I plan to shed light on optical and magnetic properties of Sr doped GdCrO₃ samples. Quantitative structural analysis and vibrational spectroscopy are used to investigate solid solubility of Sr⁺² ion in Gd_1-xSr_xCrO₃ samples. Larger cell volume and breaking of magnetic exchange pathways through nonmagnetic element (Sr) weaken the interaction strength which consequently lower Neel and spin reorientation temperatures. Presence of mixed valence sate of Cr induces a reduction of optical band gap with increase of Sr content. The most significant observation is that the dopant Sr enhances coercivity.

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