Extrinsic Effects on the Impedance Spectra of LaYFe2O6.

This work represents an effective approach to witness the true impedance profiles of the material. Here, a double-perovskite material LaYFe₂O₆ is prepared by the sol–gel auto-combustion method, which is characterized by the x-ray diffraction (XRD), field emission scanning electron microscope (FESEM), thermogravimetric analysis (TGA)–differential scanning calorimetry (DSC), and electrochemical impedance spectroscopy (EIS) technique. The XRD measurement confirms the successful synthesis of the said material with orthorhombic crystal structure having symmetry P2₁nm (~ 90%) and a slight contribution from Pbnm phase (~ 10%). The FESEM image suggests porous nature of the sample having grain size ~ 150 nm, sintered at 1473 K. TGA with simultaneous DSC measurement shows slight but gradual mass loss (related to adsorbed gases/vapors) above 400 K. The EIS shows influence of the adsorbed gases/vapors in the pores of the pellet on the impedance data. In this context, a homemade open-atmospheric impedance measurement setup is developed. The EIS measurement are done for (1) as-prepared sample, (2) sample preheated to 473 K before performing EIS, and (3) sample preheated to 400 K under vacuum. The process giving best result (having minimum effect of the adsorbed gases on the observed impedance spectra) is found by following the method (2). [ABSTRACT FROM AUTHOR]