Enhanced dielectric and optical properties in Al-substituted KBiFe2O5. (2022)

• Record Type: Journal Article
• Authors: Sahoo, Payala; Pati, Anupama; Kumari Ray, Sujata; Sahoo, A.K.; Dash, S.
• Is Part Of: Materials today. Volume 62:Part 10(2022)
• Page Start: 6029
• Page End: 6033
• Publication Date: 2022
• Subjects: Brownmillerite -- Rietveld refinement -- Band gap -- Dielectric constant; Materials science -- Congresses -- Periodicals; 620.1
• DOI: 10.1016/j.matpr.2022.04.991
• Languages: English
• ISSNs: 2214-7853

Abstract

Abstract: We report a significant effect of Aluminum (Al 3+ ) substitution on the structural, optical and dielectric properties in brownmillerite KBiFe2 O5 (KBFO) multiferroic. Polycrystalline samples of KBiFe2-x Alx O5 ( x = 0, 0.2) are synthesized by citrate combustion method. From the Rietveld refinement of X-ray diffraction analysis, both the samples are found to crystalize in a monoclinic structure possessing P2/c space group. The calculated crystallite size from the Scherer's formula is found to decrease with Al doping. The surface morphology reveals that, multiple grains of different sizes are present in all the samples and the average grain size is reduced with substitution. The optical band gap decreases from 1.739 eV to 1.715 eV with x = 0.2 of Aluminum. Furthermore, the temperature dependent Dielectric constant (ε) and dielectric loss (tan δ) of KBiFe2-x Alx O5 are investigated in a temperature range (300–773 K) at 100 Hz and 1 KHz frequency shows a substantial variation followed by a transition at around 550 K for all the samples. A comparative analysis for both the systems reveals that, for x = 0.2 of Al, an order of increase of dielectric constant appears as compared to the parent system. Additionally, the dielectric loss is also found to decrease with doping as compared to pure KBFO.