Characterization of ultra-fine amorphous particles prepared by chemical reduction

Abstract

Amorphous ultra-fine particles have been prepared in the systems of FeB and FeMB (M: transition metal) by a chemical reduction method using KBH 4 in aqueous solution. The chemical composition of the FeB particles depends on the molar ratio, M R, of KBH 4 to Fe 2+ ions on mixing. X-ray diffraction patterns show that for M R<9.0 the particles contain a crystalline phase that corresponds to a boron concentration of <30 at.%. The particles have an amorphous structure for values of M R>9.0. The results of Mössbauer measurements show that the particles consist of an amorphous phase, Fe 3+ oxide and α-Fe for M R<10.0 and of an amorphous phase and Fe 3+ oxide for M R ≧10.0 . It is also confirmed that the distribution of hyperfine magnetic field, P( B hf) changes with M R.