Electrophysical properties of different types of shungite rocks

Two types of shungite rocks with different chemical and mineralogical compositions, initial and modified, were studied. During heat treatment, nanoscale hollow carbon structures, fibrous silicon carbides, micro-sized iron silicide particles, and glassy microspheres were formed in the modified samples. The electrical conductivity of these samples at temperatures between 77 and 300 K and shielding effectiveness at frequencies from 100 kHz to 1 GHz were measured. The initial and modified samples exhibited a semiconductor type of conductivity, with activation energies ranging from 0.0007 to 0.0086 eV. The electrical conductivity and shielding effectiveness of the modified shungite samples can increase or decrease depending on the type and composition of the rock.