Graphitic Phase of NaCl. Bulk Properties and Nanoscale Stability.
We applied the ab initio approach to evaluate the stability and physical properties of the nanometer-thickness NaCl layered films and found that the rock salt films with a (111) surface become unstable with thickness below 1 nm and spontaneously split to graphitic-like films for reducing the electrostatic energy penalty. The observed sodium chloride graphitic phase displays an uncommon atomic arrangement and exists only as nanometer-thin quasi-two-dimensional films. The graphitic bulk counterpart is unstable and transforms to another hexagonal wurtzite NaCl phase that locates in the negative-pressure region of the phase diagram. It was found that the layers in the graphitic NaCl film are weakly bounded with each other with a binding energy order of 0.1 eV per stoichiometry unit. The electronic band gap of the graphitic NaCl displays an unusual nonmonotonic quantum confinement response.
†Technological Institute for Superhard and Novel Carbon Materials, 7a Centralnaya Street, Troitsk, Moscow 142190, Russian Federation.|‡Moscow Institute of Physics and Technology, Dolgoprudny 141700, Russian Federation.|§Emanuel Institute of Biochemical Physics, 4 Kosigina Street, Moscow 119334, Russian Federation.
Alexander G
AG
Kvashnin
†Technological Institute for Superhard and Novel Carbon Materials, 7a Centralnaya Street, Troitsk, Moscow 142190, Russian Federation.|‡Moscow Institute of Physics and Technology, Dolgoprudny 141700, Russian Federation.|§Emanuel Institute of Biochemical Physics, 4 Kosigina Street, Moscow 119334, Russian Federation.|∥National University of Science and Technology MISiS, 4 Leninskiy Prospekt, Moscow 119049, Russian Federation.
Pavel B
PB
Sorokin
⊥Physics and Astronomy Department, Michigan State University, East Lansing, Michigan 48824, United States.
David
D
Tománek
dipole; nanometer thick films; phase transition; sodium chloride; two-dimensional materials