Uniaxial Tensile-Induced\nPhase Transition in Graphynes

The field of materials science has a strong focus on\nthe study\nof two-dimensional (2D) materials, with particular emphasis on graphene\n(GR) and its various allotropes such as graphynes (GYs). In this work,\nwe explored through molecular dynamics simulations at finite temperatures\nthe effects of uniaxial loading on GY structures, which led to new\nphases that arise at specific temperatures. We identified three new\nphases in α- and [14, 14, 18]-GYs, which we named C<sub>16</sub>-GY, C<sub>14</sub>-GY, and C<sub>12</sub>-GR. These phases have\nthe remarkable property of remaining stable in a wide range of temperatures\n(<i>T</i> ≤ 4 and 300 K ≤ <i>T</i> ≤ 600 K). Moreover, we have conducted extensive investigations\ninto the mechanical properties of these newly discovered phases. Through\nmolecular dynamics simulations at finite temperatures, using empirical\npotential, we have gained valuable insights into how these materials\nbehave under different temperature conditions. Our results reveal\nthat at room temperature (300 K), C<sub>16</sub>-, C<sub>14</sub>-GYs\nexhibit high Young moduli in the <b>x</b>-direction (58.85 and\n65.88 N/m) compared to α- and [14, 14, 18]-GYs (46.63 and 43.98\nN/m), respectively. Additionally, these new phases exhibit mechanical\nproperties that exceed those of phosphorene, germanene, silicene,\nand stanene. Importantly, both their mechanical and dynamic stability\nhave been positively confirmed. As a result, these materials are promising\ncandidates for various mechanical applications.