Effect of Sm3+ ion addition on gas sensing properties of Mg1−xCdxFe2O4 system

5 wt% Sm3+ added nanocrystallite ferrite samples with general formula Mg1−xCdxFe2 O4 (x = 0, 0.2, 0.4, 0.6, 0.8 and 1) were prepared by oxalate co-precipitation method from high purity sulphates. The XRD, SEM and FT-IR techniques were used for characterization of the samples. The XRD confirms cubic spinel structure with orthoferrite (SmFeO3) secondary phase. The crystallite size varies from 28.69 to 32.66 nm. The surface morphology SEM study shows increase in grain size with Cd2+ concentration, while it decrease due to Sm3+ addition in Mg–Cd ferrites. The FT-IR spectra show two strong absorption bands in the range of 350–800 cm−1. The response decreases with Cd2+ concentration for LPG, Cl2 while increases for C2H5OH. The response of Sm3+ added Mg–Cd ferrite is higher than Mg–Cd ferrite. The response and recovery time of Sm3+ added Mg–Cd ferrites decreases with increase in Cd2+ concentration and lower than Mg–Cd ferrites. The shorter response and recovery time is observed for Sm3+ added Cd ferrite sensor compared to other samples. The response depend on the composition, test gas and grain size of the material.