Co1−xBaxFe2O4 (x = 0, 0.25, 0.5, 0.75 and 1) nanoferrites as gas sensor towards NO2 and NH3 gases

Abstract

Co_1−xBa_xFe₂O₄ (x = 0, 0.25, 0.5, 0.75 and 1) nanoferrites were synthesized using a controlled chemical co-precipitation technique. Their structural, optical, dielectric and gas sensing properties were characterized by X-ray diffractometry, UV-Vis spectroscopy and an LCR meter with a gas sensing unit. The crystalline sizes were estimated using the Scherrer formula and were found to be 7.8 nm, 14.4 nm, 21.8 nm, 16.5 nm and 30.3 nm for x = 0, 0.25, 0.5, 0.75 and 1, respectively. The fundamental optical band gaps were calculated by extrapolating the linear part of (αhυ)² vs. hυ of the synthesized nanoferrites. The SEM and EDX spectra also confirmed the formation of nanoferrites. Dramatic behavior was observed in the dielectric constant and dissipation factor with varying temperature, which provides a substantial amount of information about electric polarization. The synthesized nanoferrites were tested towards NO₂ and NH₃ gases. The order of sensitivity (%) towards NH₃ was analyzed as x = 0.75 > x = 0.5 > x = 0.25 > x = 0 > x = 1, while the order was x = 0 > 0.75 > 1 > 0.5 > 0.25 for NO₂ gas.