Co1−xBaxFe2O4(x= 0, 0.25, 0.5, 0.75 and 1) nanoferrites as gas sensor towards NO2and NH3gases

Abstract

Co1−xBaxFe2O4(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 forx= 0, 0.25, 0.5, 0.75 and 1, respectively. The fundamental optical band gaps were calculated by extrapolating the linear part of (αhυ)2vs. hυof 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 NO2and NH3gases. The order of sensitivity (%) towards NH3was analyzed asx= 0.75 >x= 0.5 >x= 0.25 >x= 0 >x= 1, while the order wasx= 0 > 0.75 > 1 > 0.5 > 0.25 for NO2gas.