Regular Article

Linking tracks in mica crystals with phase transitions in a bistable lattice

¹ Institute for Metals Superplasticity Problems RAS, Ufa 450001, Russia
² Ufa State Aviation Technical University, Ufa 450077, Russia
³ North-Eastern Federal University, Polytechnic Institute (branch) in Mirny, 678170 Mirny, Sakha (Yakutia), Russia
⁴ Karlsruhe Institute of Technology, Institute for Applied Materials – Applied Materials Physics, Eggenstein-Leopoldshafen 76344, Germany
⁵ National Research Tomsk State University, Tomsk 634050, Russia

^a e-mail: elena.a.korznikova@gmail.com

Received: 20 November 2019
Received in final form: 19 December 2019
Published online: 3 February 2020

Abstract

Since the middle of the last century, scientific research has been conducted to explain the nature of the tracks visible to the naked eye in mica muscovite crystals. In the present work, an attempt to link the appearance of tracks with a phase transition in a bistable medium is made using classical molecular dynamics method. For this purpose, a two-dimensional triangular lattice simulating one row of potassium atoms in mica is considered. Interactions between atoms are described via pairwise Morse potential and a local potential, whose minima create a hexagonal lattice. In order to create a bistability in the system, a mismatch between the equilibrium distance of the triangular lattice and the period of the local potential is artificially introduced. The phase transitions arising from a monotonic increase or decrease of the depth of the local potential are described. It is revealed that at lower temperatures the domains of different phases can coexist, but at higher temperatures the domain with lower potential energy grows with heat release by reducing the high energy domain. It is speculated that the considered model, which provides the possibility of coexistence of two different phases, can be used to explain at qualitative level the nature of dark tracks visible with the naked eye in transparent crystals of mica muscovite.