Infinite charge mobility in muscovite at 300 K

¹ Group of Nonlinear Physics, Department of Applied Physics I, Universidad de Sevilla - ETSII Avda Reina Mercedes s/n, 41012-Sevilla, Spain
² Group of Surfaces, Interfaces and Thin Films, Department of Applied Physics I, Universidad de Sevilla - ETSII Avda Reina Mercedes s/n, 41012-Sevilla, Spain
³ X-Ray Laboratory (CITIUS), Universidad de Sevilla - Avda Reina Mercedes 4B, 41012-Sevilla, Spain

^(a) archilla@us.es

Received: 12 October 2017
Accepted: 15 January 2018

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 the 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 ⁴⁰K. 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.