The Surface Study of Amorphous Ni-B Ultra-fine Particles by AES

The amorphous Ni_2.52 B ultrafine particles were prepared by reducing Ni²⁺ ion with KBH4 in ethanol solution. The Auger electron spectroscopy （AES） was used to study the variations of surface composition with temperature, Ar⁺ sputter time and the exposure of oxygen.Two kinds of boron species were observed, they were assigned to boron interacting with nickel and oxidized boron, respectively. The oxidized boron were Produced both in the reduction process of Ni²⁺ and the oxidation processs of boron. It was also noticed that boron was preferentially oxidized in oxidation, and the oxidation of boron induced the decrease of surface concentration of nickle and the increase of concentration of boron species. The obviously change of surface composition was also observed by heating treatment. When the temperature was lower than 590K, the concentration of surface atoms changed a little. When the temperature was higher, the nickle almost disappeared, and the further investigations are needed to make sure the reason.