Synthesis of Nickel Ferrite / Cadmium Oxide Compound Nanoparticles by Co-precipitation Method and Investigation its Sensitivity to Formaldehyde

In this study, NiFe2O4-CdO compound nanoparticles were prepared through co-precipitation. The two variables of the synthesis method are, respectively, the temperature gradient reaching the temperature of the heat treatment of 500 ° C at 10°C/sec, 35°C/sec and 60 °C/sec and the pure oxygen pressure as the heat treatment atmosphere for 0.5 hours, at 0.5 psi, 1 psi, and 1.5 psi. So, we found 9 samples, that the sample with the best sensitivity response to formaldehyde was characterized. X-ray diffraction, scanning electron microscopy, transition electron microscopy and X-ray fluorescence experiments were used to study the structure of these nanoparticles. X-ray diffraction experiment is confirmed formation of nickel ferrite and cadmium oxide phases. Scanning electron microscopy and transition electron microscopy experiments are confirmed nickel ferrite and cadmium oxide being nano-structure. NiFe2O4-CdO formula ratio is confirmed by X-ray fluorescence experiment. The sensitivity property of NiFe2O4-CdO nanoparticles for formaldehyde gas detection was studied at 50 °C. For testing the sensitivity of nanosensors, we used a laboratory 5 liters system with temperature and humidity control. This system equipped with a temperature control heater for heating sensors. Relationship between gas concentration (from 10 ppm to 200 ppm) and resistance change of nano sensor with the best response to formaldehyde was investigated, that this relationship was found linear.