Abstract:Nickel ferrite nano-powders were prepared by microwave radiating low-temperature solid-state reaction method, and then modified with Ag by dipping method. The crystal structure and morphology of the samples were characterized by means of X-ray diffraction(XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The gas sensing properties of the samples were also investigated. The results reveal that the Ag, as amorphous structure, can efficiently prevent the reuniting and growing-up of nanosized NiFe₂O₄ grains, and 1.5% Ag modified NiFe₂O₄ sensor has a better sensitivity, up to 43, for acetone gas than 1.5%Ag mixed NiFe₂O₄ sensor prepared by low-temperature solid-state reaction, at an optimal working voltage of 4.5 V. The quick response time (1 s) and fast recovery time (~10 s) are the main characteristics of this sensor.

Key words: nickel ferrite; low temperature solid state reaction; dipping method; silver; acetone