Synthesis of strontium ferrite ultrafine particles using microemulsion processing

The strontium ferrite ultrafine particles have been prepared using the micr oemulsion processing. The mixed hydroxide precursor was obtained via the co precipitation of Sr2+ and Fe3+ in a water-in-oil microemulsion of water/CTA B/n-butanol/isooctane. According to the investigation on the thermochemical properties by TGA/DTA and the phase analysis by XRD, it was shown that the precursor could yield pure strontium ferrite after calcination at 700 degr eesC for 5 h while using an appropriate molar ratio of Sr/Fe in microemulsi ons. From TEM measurement, the diameters of the precursor and calcined part icles were 3.8 +/- 0.7 and 50-100 nm, respectively. The magnetic properties characterized by a SQUID magnetometer showed that the saturation magnetiza tion, remanent magnetization, coercivity, and squareness ratio were 55 emu/ g, 28 emu/g, 492 Oe, and 0.51, respectively. The magnetization was also obs erved to increase with the decrease of temperature at 5-400 K. Compared wit h those reported earlier, the quite low coercivity implies the potential ap plication of final product in the high-density perpendicular recording medi a. (C) 2001 Academic Press.