Magnetic, gas sensing properties, and structural parameters of barium-calcium hexaferrite synthesized by sol-gel auto combustion method

Sol-gel combustion method has been used to obtain nano-sized particles of barium-calcium hexaferrite Ba1-xCaxFe12O19 (0 <= x <= 1). The dried gel samples were calcined at 950 degrees C for 4.5 hr. The phase evaluation and microstructure of calcined samples were investigated by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) techniques, respectively. The result revealed the formation of barium-calcium hexaferrite phase with a small amount of hematite as a secondary phase. There is a variation of particle size from 20 to 500 nm and a combination of plates-like hexagonal and spherical morphology of particles for synthesized samples. The measured magnetic properties of synthesized samples, using a vibrating sample magnetometer (VSM), revealed that the sample synthesized with x = 0.4 exhibited the lowest level of magnetization saturation in comparison with others, which can be due to the heterogeneity of the structure and the presence of nonmagnetic phases such as BaFe2O4 and Fe2O3. The obtained results of sensory tests in acetone gas showed that the barium-calcium hexaferrite sample with x = 0.2 exhibits the highest sensitivity (S = 0.57) and shortest response time (t(r) = 20 s) under the conditions of 900 ppm of concentration and 300 degrees C of temperature, although the recovery time is long.

Automated summary

Sol-gel combustion method was used to obtain nano-sized particles of barium-calcium hexaferrite. The synthesized samples showed diverse particle morphology and size, and their magnetic and sensory properties varied with different chemical compositions.