title: Superheating of monolayer ice in graphene nanocapillaries.
abstract: The freezing and melting of low-dimensional materials, either via a first-order phase transition or without any discontinuity in thermodynamic, still remain a matter of debate. Melting (superheating) in two-dimensional (2D) ice is fundamentally different from that in bulk counterpart. Here, we perform comprehensive molecular dynamics simulations of the superheating of monolayer ice in graphene nanocapillaries to understand the nature of melting transition in 2D water/ice. We find four different superheating (melting) scenarios can happen in the superheating of monolayer square-like ice, which are closely related to the lateral pressure and the channel width. The anomalous two-stage melting transition with arisen coexistence phase is found, which reveals the unknown extraordinary characteristics of melting in 2D water/ice. Under ultrahigh lateral pressure, the intermediate monolayer triangular amorphous ice will be formed during the superheating of monolayer square-like ice with both continuous-like and first-order phase transitions. Whereas, under low lateral pressure, the melting in monolayer square-like ice manifests typical discontinuity with notable hysteresis-loop in potential energy during the heating/cooling process. Moreover, we also find that highly puckered monolayer square-like ice can transform into bilayer AB-stacked amorphous ice with square pattern in the superheating process. The superheating behavior under high lateral pressure can be partly regarded as the compression limit of superheated monolayer water. The intrinsic phenomena in our simulated superheating of monolayer ice may be significant for understanding the melting behavior in 2D water/ice.
authors.affiliation: CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, CAS Center for Excellence in Nanoscience, University of Science and Technology of China, Hefei, Anhui 230027, China.
authors.forename: YinBo
authors.identifier: 0000000192049300
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, CAS Center for Excellence in Nanoscience, University of Science and Technology of China, Hefei, Anhui 230027, China.
authors.forename: FengChao
authors.identifier: 0000000259543881
authors.initials: F
authors.lastname: Wang
authors.affiliation: CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, CAS Center for Excellence in Nanoscience, University of Science and Technology of China, Hefei, Anhui 230027, China.
authors.forename: HengAn
authors.initials: H
authors.lastname: Wu