Infinite charge mobility in muscovite at 300K

TL;DR

This paper demonstrates that natural muscovite mica crystals exhibit infinite charge mobility at room temperature, with charge propagating over great distances along atomic chains without applied voltage.

Contribution

It provides evidence that positive charge can move freely in muscovite crystals via lattice excitations, a novel insight into charge transport in insulators.

Findings

Charge propagates over distances thousands of times greater than particle ranges.

Charge movement is associated with anharmonic lattice excitations.

Charge mobility appears effectively infinite within crystal size limits.

Abstract

Evidence is presented for infinite charge mobility in natural crystals of muscovite mica at room temperature. Muscovite has a basic layered structure containing a flat monatomic sheet of potassium sandwiched between mirror silicate layers. It is an excellent electrical insulator. Studies of defects in muscovite crystals indicated that positive charge could propagate over great distances along atomic chains in the potassium sheets in absence of an applied electric potential. The charge moved in association with anharmonic lattice excitations that moved at about sonic speed and created by nuclear recoil of the radioactive isotope K40. This was verified by measuring currents passing through crystals when irradiated with energetic alpha particles at room temperature. The charge propagated more than 1000 times the range of the alpha particles of average energy and 250 times the range of channelling particles of maximum energy. The range is limited only by size of the crystal.