Synthesis of Size-Controlled SrFe12O19 Using Modified Spray Pyrolysis-Calcination Method and Their Magnetic Properties

Strontium hexaferrite (SrFe12O19, SrM) suitable for high-performance permanent magnet applications was synthesized by salt-assisted ultrasonic spray pyrolysis (SA-USP) and subsequent calcination. To control the particle size, the intermediate phase of SrM was collected by SA-USP and various sizes of SrM were obtained by calcining the as-prepared sample at temperatures ranging from 800A degrees C to 1050A degrees C. The synthesized SrM was magnetically aligned by using an external magnetic field to improve remanence. The synthesized particles were of nano- to submicron scale and nonagglomerated. The magnetic properties and squareness of the material depended on the particle size and distribution. Additionally, the NaCl added during synthesis facilitated the formation of nonagglomerated particles, while enhancing and controlling particle growth. The optimum magnetic properties were achieved at calcination temperature of 1000A degrees C, resulting in coercivity of 5646 Oe, saturation magnetization of 73.3 emu/g, and remanence of 59.1 emu/g (80.6% of M (s)).We acknowledge a National Research Foundation of Korea (NRF) Grant funded by the Korea government (MSIP) (No. 2008-0061891) and support from the Pioneer Research Center Program through the National Research Foundation of Korea (NRF-2012-0001262) funded by the Ministry of Science, ICT, and Future Planning