Transactions of Nonferrous Metals Society of China
JOURNAL OF RAILWAY SCIENCE AND ENGINEERING
|Vol. 11 No. 3 June 2001|
M-type hexagonal barium ferrite fine powders
（Department of Metallurgy Science and Engineering,
Central South University,Changsha 410083, P.R.China）
Abstract: The hexagonal BaLaxFe12-xO19 fine powders with M-type structure were synthesized by sol-gel method. The pH of the solution, the molar ratio of nitrate to citric acid and the calcination temperature were investigated to clarify the forming conditions of the ferrites. The crystal structure, grain size, form and magnetic properties were studied by means of XRD, SEM and vibrating sample magnetometer. It is concluded that at pH of 7.0 or so, molar ratio of nitrate to citric acid of 1/3 and calcination temperature of 850 ℃(1 h)，1 000 ℃, M-type BaLax Fe12-xO19 fine powders with a particle size of less than 300 nm was obtained.
Key words: so-gel method； rare earth； permanent magnetic ferrite； citrate