Uniaxial Tensile-Induced Phase Transition in Graphynes

The field of materials science has a strong focus on
the study
of two-dimensional (2D) materials, with particular emphasis on graphene
(GR) and its various allotropes such as graphynes (GYs). In this work,
we explored through molecular dynamics simulations at finite temperatures
the effects of uniaxial loading on GY structures, which led to new
phases that arise at specific temperatures. We identified three new
phases in α- and [14, 14, 18]-GYs, which we named C16-GY, C14-GY, and C12-GR. These phases have
the remarkable property of remaining stable in a wide range of temperatures
(T ≤ 4 and 300 K ≤ T ≤ 600 K). Moreover, we have conducted extensive investigations
into the mechanical properties of these newly discovered phases. Through
molecular dynamics simulations at finite temperatures, using empirical
potential, we have gained valuable insights into how these materials
behave under different temperature conditions. Our results reveal
that at room temperature (300 K), C16-, C14-GYs
exhibit high Young moduli in the x-direction (58.85 and
65.88 N/m) compared to α- and [14, 14, 18]-GYs (46.63 and 43.98
N/m), respectively. Additionally, these new phases exhibit mechanical
properties that exceed those of phosphorene, germanene, silicene,
and stanene. Importantly, both their mechanical and dynamic stability
have been positively confirmed. As a result, these materials are promising
candidates for various mechanical applications.