Studying the nature of paramagnetic centres in amorphous powders 10B and 11B using ESR method

Amorphous powders of boron were studied by ESR method at the frequency of 9.5 GHz in the temperature range of 100-450 K. Enrichment of 10B constituted 80.5% and that of 11B -99.5%. It is shown that holes captured on the trap levels are paramagnetic centres in amorphous powders of 10B and 11B isotopes. The centres are volumetric and are characterized by the factor of spectroscopic splitting g=2.0029±0.0002. On the basis of measurements of temperature dependence of paramagnetic centre concentration and ESR line width the energy parameter of the trap level: 0.11 eV over valency band, is determined. The observed great narrowing of ESR line with the temperature increase is related to the increase in electron delocalization frequency. The experimental results obtained confirm the location of atoms in amorphous boron in icosahedrons