Possible pair-graphene structures govern the thermodynamic properties of arbitrarily stacked few-layer graphene

Abstract

The thermodynamic properties of few-layer graphene arbitrarily stacked on LiNbO3 crystal were characterized by measuring the parameters of a surface acoustic wave as it passed through the graphene/LiNbO3 interface. The parameters considered included the propagation velocity, frequency, and attenuation. Mono-, bi-, tri-, tetra-, and penta-layer graphene samples were prepared by transferring individual graphene layers onto LiNbO3 crystal surfaces at room temperature. Intra-layer lattice deformation was observed in all five samples. Further inter-layer lattice deformation was confirmed in samples with odd numbers of layers. The inter-layer lattice deformation caused stick–slip friction at the graphene/LiNbO3 interface near the temperature at which the layers were stacked. The thermal expansion coefficient of the deformed few-layer graphene transitioned from positive to negative as the number of layers increased. To explain the experimental results, we proposed a few-layer graphene even–odd layer number stacking order effect. A stable pair-graphene structure formed preferentially in the few-layer graphene. In even-layer graphene, the pair-graphene structure formed directly on the LiNbO3 substrate. Contrasting phenomena were noted with odd-layer graphene. Single-layer graphene was bound to the substrate after the stable pair-graphene structure was formed. The pair-graphene structure affected the stacking order and inter-layer lattice deformation of few-layer graphene substantially.

Contactless Scanning Near‐Field Optical Dilatometry Imaging at the Nanoscale

“…[56] Furthermore, the linear TEC above 175 layers undergo a plateau at (33.75 ± 3.24)×10 −6 K −1 which is consistent with the out-of-plane thermal expansion of graphite along the crystallographic c-axis, [55][56][57][58] which corroborates the validity of SNOD as an accurate and quantitative method for thermal expansivity measurements. Conversely, a value of (−5.77 ± 3.79)×10 −6 K −1 is observed via SNOD for the thinnest ML-G platelets, below ≈ 90 layers, which can be assigned to the in-plane bending modes of graphene, [55,56] and is consistent with previous macroscopic measurements, [56][57][58][59][60][61][62][63][64][65][66][67][68][69] as shown in Table 2. A significant advantage of SNOD over all of such techniques rests in that it provides site-specific thermal expansion information, while other probing methods only yield an ensemble aver-age of the thermally induced expansion and offer minimal information on the distribution of the thermal expansion throughout the whole sample.…”

“…Our apparatus, a scanning near-field dilatometer, is all-optical in nature and, therefore, does not require any external heater or electrical contact to vary the sample's temperature, nor it requires any physical thermometer or nano-thermocouple to probe it. Our method is a 𝜔-2𝜔 pump-probe method, where the probe is an aperture-type reflection-mode SNOM, which makes it uniquely suited for probing optically absorbing and thermally conducting See References Graphite 0-40 [57][58][59] Nano EELS Graphene/ Cu Mesh Mono−2.14 ± 0.79 Bilayer−1.09 ± 0.25 Trilayer−0.87 ± 0.17 Bulk−0.07 ± 0.01 [60] Low Temperature Resonance Au/Graphene/SiO 2 /Si −7.4 [61] Raman Spectroscopy Graphene/LiNbO 3 −10 to -5 [62] Au/Graphene/ SiO 2 /Si Mono−3.2 ± 0.2 [63] Bilayer−3.6 ± 0.4…”

A Spear and Shield‐Inspired Ar Plasma Safeguard Few‐Layer Black Phosphore with Firefighting of Epoxy Resin

“…[1][2][3][4] They possess novel outstanding properties and attractive applications in a series of technological fields, such as electronic and optoelectronic devices, photocatalysis and electrocatalysis, and biological applications. [5][6][7] Layer-by-layer 2D materials are usually prepared via various approaches including micromechanical cleavage, ball milling, and liquid exfoliation in ionic liquids the release of harmful pyrolysis products are also dramatically reduced. [17] Zhou et al fabricated BPNSs and reduced graphene oxide (BP-RGO) nanohybrids by solvothermal tactic to promote the dispersed state of BPNSs in EP and elevate its fire retardancy property, where the RGO was connected on the surface of BPNSs via PC and POC bonds.…”

“…[ 1–4 ] They possess novel outstanding properties and attractive applications in a series of technological fields, such as electronic and optoelectronic devices, photocatalysis and electrocatalysis, and biological applications. [ 5–7 ] Layer‐by‐layer 2D materials are usually prepared via various approaches including micromechanical cleavage, ball milling, and liquid exfoliation in ionic liquids or organic solvents. [ 8–12 ] BPNSs, a rising star among 2D materials beyond graphene, possess unique physicochemical properties.…”