Semiconducting gas sensor for acetone based on the fine grained nickel ferrite

The sensitivity to some reducing gases (acetone, ethanol, methane and liquefied petroleum gas—LPG) of calcia doped nickel ferrite (NiFe2O4 + 1%CaO) and cobalt and manganese doped nickel ferrite, Ni0.99Co0.01MnxFe2−xO4−δ (x = 0.01 and 0.02), was investigated. Starting from nitrates, as raw materials, the samples were prepared by selfcombustion method. The nanosized powders were obtained by quick combustion. After a 30 min heat treatment at 1273 K of the compacted powder in a disk shape, some investigations of the ferrite disks were carried out by X-ray diffraction, scanning electron microscopy and measurements of the electrical resistivity sensitivity to the four test gases. The response time was studied, too. The gas sensitivity largely depends on the composition, temperature and the test gas species. The ferrite compounds doped with Co and Mn are selective to detect reducing gases at low operating temperature. The mixed ferrite with Ni0.99Co0.01Mn0.02Fe1.98O4−δ composition is sensitive and selective to acetone gas.