No abstract

No abstract

Electron paramagnetic resonance (EPR) signals from powdered samples of boron carbide B4C are recorded at g factor 2.0028±0.0002. The dependence on temperature and thermal treatment of the samples is studied. We demonstrated that native defects of boron carbide and conduction electrons are responsible for EPR absorption. The temperature dependence of the EPR line width ΔB(T) is accounted for via the Korringa mechanism. By fitting experimental and theoretical curves for ΔB(T), distances of donor levels from the edge of the conduction band ΔEd are obtained. The process of sample preparation strongly effects the value of ΔEd. We assume a radical formation of the type B3C with local concentration Nloc∼1019–2×1020 cm−3 is responsible for the EPR signal under these conditions.

No abstract

No abstract