SURFACE-REACTIONS AND STRUCTURES OF NIOBIUM OXIDE SUPERFINE PARTICLES

The surface states of niobium oxide superfine particles (NOSPs) are in vestigated by analyzing the pressure dependence of the dispersion of c omplex dielectric constants. NSOPs were formed by a magnetron sputteri ng system. The average size was 260 +/- 25 Angstrom. The lattice const ant is a = 3.45 Angstrom (bcc). NOSPs were a metastable materials whic h contained 50 at% oxygen. The density distributions of electric dipol es due to the surface state on the particles were obtained by approxim ating the data with theoretical curves. The reactivity of NSOPs was in vestigated on O-2, Ar and N-2. The surface reactivity of NOSPs strongl y depended on the oxidation process of the niobium superfine particles . The influences of adsorption of argon were observed at the frequency regions 200 Hz < omega < 3 kHz and 400 kHz < omega, where the electri c dipole density increased above 0.1 Torr of argon. In N-2 gas, the an omalies of density of electric dipoles were observed at higher regions of the frequency and the gas pressure; 600 Hz < omega and P-N2 > 4 To rr, respectively.