Enhanced performance of SnO2-Mn(1−X)Cu(X)Fe2O4 gas sensors towards carbon dioxide and oxygen

Mn(1−X)Cu(X)Fe2O4 nanoparticles with different 'X' values (X = 0, 0.5, 1.0) are synthesized initially by the chemical co-precipitation method and followed by equal (1:1) weight percentages of Cu/MnFe2O4 are combined with SnO2. XRD parameters of all the materials are well agreed with the standard JCPDS files and confirm the presence of polycrystalline cubic spinel structure for ferrite materials and tetragonal phase for SnO2. The addition of SnO2 on copper substituted manganese ferrite increases the crystalline size and decreases the strain values. Morphological analysis for ferrite material depicts the average particle size is linearly decreased with the decrease in Mn2+ concentration. Moreover, the addition of SnO2 on ferrite materials increases the particle size. VSM analysis exhibits superparamagnetic behaviour for all the samples except SnO2 and MnFe2O4. The observed Ms values are diluted with the addition of SnO2 on ferrite materials. Pure SnO2 shows a weak paramagnetic behaviour and MnFe2O4 shows a ferromagnetic nature with the MR = 0.318 emu/g and Hc = 0.0019 T. EDAX spectrum for SnO2, MnFe2O4, CuFe2O4 and Mn0.5Cu0.5Fe2O4 shows the observed stoichiometric ratios for all the samples are in accordance with chemical formulas. The gas sensing properties of MnFe2O4, Mn0.5Cu0.5Fe2O4, CuFe2O4 and SnO2 added Cu/Mn ferrite materials are studied for O2 and CO2. SnO2-MnFe2O4 and SnO2-Mn0.5Cu0.5Fe2O4 samples under gas sensor test shows better response than pure MnFe2O4 and Mn0.5Cu0.5Fe2O4 for both O2 and CO2. After gas reduction, the material shows almost a pristine behaviour confirms these materials are suitable for gas sensor application. However, in the case of SnO2-CuFe2O4 shows a decrease in trend of gas response when compared to pure copper ferrite.