Effect of pH value on the structural and magnetic properties of nanocrystalline strontium hexaferrite thin films

Strontium hexaferrite SrFe12O19 thin films have been synthesized at different pH, adjusted by NH4OH, on the Si (1 0 0) substrate using a spin coating sol–gel process. Fourier transform infrared spectroscopy analysis and theoretical calculations were conducted for determination and controlling metal citrates in solution precursors. X-ray diffraction, scanning electron microscopy and vibrating sample magnetometer were applied to evaluate the composition, microstructure, crystallite size and magnetic properties of the SrFe12O19 thin films. Using the solution with pH 7, the approximately single phase strontium hexaferrite thin films with optimum physical properties can be obtained at calcination temperature of 800 °C. The SrFe12O19 thin films derived from the solution with pH 7 after calcination at 800 °C exhibited crystallite size of 42 nm and magnetic properties of Ms=267 emu/cm3 (at 10 kOe), Mr=134 emu/cm3 and Hc=4290 Oe.

► Preparing of strontium hexaferrite thin film by sol–gel spin coating based on the Pechini method.
► The films prepared from the solutions with different pH=1 to 7.
► The film with pH=7 has the lowest calcination temperature of 800 °C.