Research of the quasistable self-potential effect of highly-metamorphic coal in laboratory conditions

Abstract

The article focuses on a quasistable electrical potential registered on samples of highly-metamorphic and high-ash coal in normal laboratory conditions. The purpose of the study is to determine the possible conditions for the appearance of their effect in the coal and carbon-like argillite and the parameters of its structure. The appearance of an uncompensated charge is not associated with thermoelectric and electrokinetic phenomena and it has not been previously described. Most samples are characterized by an uneven distribution of charges along the surface in the form of a polydomain structure. Polarized samples have a layered coal-mineral structure. The charge magnitude depends on the thickness and density of the layers. In heterogeneous and heterophase substances the Maxwell-Wagner polarization is realized, arising on the boundary layers of dielectric micrograins of various substances, as well as between the areas of one dielectric with an amorphous and crystalline phase. Microinclusions and anthracite layers, which increase the potential ability of mineral components to their own polarization, can be conductors. Charged samples may have a stable, non-compensated monodomain residual charge under constant external conditions, which is characteristic of the electrets. The detected effect can be useful when creating alternative devices accumulating electricity.

Signs of dynamic nonlinearity of the coal dielectrics depolarization upon excitation in electric and magnetic field

“…In previous research, we studied the impact of environmental temperature and humidity on the parameters of natural self-potential and relaxation dynamics of charged coal samples of different ranks [6]. The purpose of these studies is to consider the impact of external electric and magnetic fields on the slow relaxation dynamics of the electric charge in the studied coals, which are active dielectrics with ferroelectric properties.…”