Desenvolvimento de sensores de gases à base de ferritas do tipo MFe2O4 (M = Mn, Zn e Ni)

Abstract

Ferrites are a class of chemical compounds with the formula AB2O4, where A and B represent various metal cations, usually including iron. These ceramic materials are used for permanent magnets, high density magnetic recording media and gas sensors. Compounds of the type MFe2O4 (M = Mn, Ni e Zn) were prepared varying the milling time (1h, 3h, 6h and 9h) and using a shaker mill, with vial and balls of hardened steel, under argon atmosphere. The asmilled powders were structurally characterized by X-ray diffraction, at room temperature. In all X-ray diffraction patterns, a broadening of the difraction peaks was observed, revealing the strong particle size reduction of the milled products. The X-ray diffraction patterns of the samples milled for 6 h e 9 h showed that the ferrite phase is the main phase in all the samples. Thermoelectroresistometry (TER) consists on the measure of the electric resistance in function of the temperature. TER showed that the samples are sensitive to methane gas (CH4) and carbon dioxide (CO2).