Electrical and thermoelectric attributes of Ba2Co2Fe12−2x(Ti–Mn)xO22 and their catalytic activity for complete N2O decomposition

Abstract

A series of Ti–Mn co-doped Ba₂Co₂Fe_12−2x(Ti–Mn)_xO₂₂ (x = 0.2–1.0) Y type hexaferrites has been synthesized by sol–gel method. Single phase hexagonal crystal structure was confirmed by X-ray diffraction analysis and Rietveld refinement with a crystallite size of 30–54 nm of the particles. Ti–Mn doping was uniform in the grains and there was no effect on the microstructure. Alternating current conductivity and dielectric properties were studied over a range of frequencies (20 Hz–3 MHz) for all the compositions. The resistivity increased with the dopant content while the dielectric constant decreased due to valence alteration of Fe³⁺ ions from the octahedral site by the dopants. Thermoelectric studies along with direct current resistivity results established the electron hopping conduction mechanism in the doped ferrites. The doped hexaferrites were used for the first time as the catalysts for complete N₂O decomposition at a low temperature of 873 K. The electronic properties along with surface vacancies were found to be responsible for their efficient catalytic activity. Stability of the prepared material for several hours at the reaction temperature added to its catalytic application.