Structural, Magnetic and Acetone Sensing Properties of Barium- Calcium Hexaferrite Synthesized by Sol- Gel Auto Combustion Method

In this research, barium calcium hexaferrite (Ba1-xCaxFe12O19 , 0≤x£1) nanoparticles were synthesized through a sol-gel combustion method. The dried gel samples were then calcined at 950ºC for 4:30h. The phase and microstructural evolution of calcined samples were investigated by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM), respectively. The results revealed formation of calcium -barium hexaferrite phase with a small amount of hematite as a secondary phase.  The average particle size is between 60-100 nm and the particle morphology is hexagonal or plate like structure. Results of a vibrating sample magnetometer (VSM) showed that the sample with x=0.4, exhibited the lowest value of saturation magnetization in comparison with others. This could be due to structural heterogeneity and presence of higher amounts of non- magnetic phases (BaFe2O4 and Fe2O3) in this sample compared to others. The results of sensory testing in acetone gas showed that the barium-calcium hexaferrite sample with x=0.2 had the highest sensitivity (0.28) and shortest response (15s) at a concentration of 900 ppm and a temperature of 200 °C despite of the long recovery time.