Correlation between structural, magnetic and gas sensor properties of La0.885Pb0.005Ca0.11Fe1-xCoxO2.95(0.00 ≤ x ≤ 0.15) compounds

Ferrite perovskite sensors based on La0.885Pb0.005Ca0.11Fe1-xCoxO2.95( where x = 0.00, 0.05, 0.10 and 0.15) were prepared using the sol-gel method. Structural, magnetic and gas sensing properties were investigated. The structural study shows that all samples crystallize in the orthorhombic system in the Pnma space group. Magnetization analysis based on M(T) curves shows the presence of a second order transition from a ferromagnetic (FM) to a paramagnetic (PM) state at the Curie temperature (T-C). T-C decreases from 709 K to 684 K when the percentage of Co increases to 10 %. Introducing cobalt instead of iron causes a decline of the maximum magnetization, which drops from 0.90 with x = 0.00 to 0.01 with x = 0.15. In addition, we find that an increase in Co content induces a decrease in the volume and porosity of the compounds. Increasing the concentration of Co thus decreases sensor sensitivity with respect to the gas to be detected, which in this study is ammonia, NH3. The normalized electrical sensor response decreases from 1.027 to 1.014 respectively for Co concentrations of x = 0.00 (undoped sample) and x = 0.05 with an exposure of 10 ppm of ammonia at 270 degrees C. We show that La0.885Pb0.005Ca0.11Fe1-xCoxO2.95 (0.00 <= x <= 0.15) -based compounds can be considered as potential candidates for ammonia detection and that in fact they are able to detect NH3 concentrations of around 10 ppm.