Delamination of multilayer graphene stacks from its substrate through wrinkle formation under high pressures

Abstract

There is a need to find new paths for van der Waals 2D-systems detachment and transfer or to control their adhesion state in different environments. We have observed that supported multilayer graphene immersed in a fluid can be detached from a substrate through pressure application. The process is based on the development of wrinkles originated by the difference of in-plane-compressibility between the graphene stacks and the substrate. Graphene stacks comprised between 9 and 110 layers and immersed in various fluids allowed to investigate the growth and evolution of wrinkles with increasing pressure. The detachment from the substrate stops at the pressure-induced fluid solidification. Methanol, ethanol or their mixtures favor the pressure-induced wrinkle formation in SiO 2 /Si substrates. In these cases, the pressure evolution of the delamination process follows a universal behavior independently of the number of graphene layers with a complete delamination at /sim4GPa. The quantitative analysis of the wrinkle geometry evolution can be consistently interpreted as due to a pressure-induced increase of the bending stiffness of the graphene stacks, or a reduction of the adhesion forces between the sample and the substrate, or both. These results should also be of practical use in high-pressure experiments of van der Waals systems.

Grüneisen parameters, bulk modulus, and thermal expansion coefficient of Na3MCO3PO4 (M = Mn, Fe, Co, and Ni) carbonophosphates

“…Here, we carried out spectroscopy studies on Na 3 MCO 3 PO 4 (M = Mn, Fe, Co, and Ni) carbonophosphates by investigating these systems under different pressure and temperature conditions to access some of their physical properties 16 . These materials are reported to have monoclinic symmetry (P2 1 /m), with Z = 2, leaving 26 atoms and 78 vibration modes (39 Raman actives and 36 IR actives), as described in detail in Tables S1 and S2 5,17–19 .…”

“…15 Here, we carried out spectroscopy studies on Na 3 M-CO 3 PO 4 (M = Mn, Fe, Co, and Ni) carbonophosphates by investigating these systems under different pressure and temperature conditions to access some of their physical properties. 16 These materials are reported to have monoclinic symmetry C 2 2h (P2 1 /m), with Z = 2, leaving 26 atoms and 78 vibration modes (39 Raman actives and 36 IR actives), as described in detail in Tables S1 and S2. 5,[17][18][19] The unit cell dimensions at ambient pressure and room temperature are a = Our calculations also result in lattice parameter values (see Figure S4, entry corresponding to zero pressure) in excellent agreement with that we found by using X-ray diffraction (XRD) and with the values reported in previous theoretical and experimental studies.…”

Pressure Tuning Resonance Raman Scattering in Monolayer, Trilayer, and Many-Layer Molybdenum Disulfide

“…Besides the thickness-dependent optical properties, external perturbations, such as strain, hydrostatic pressure, and temperature, have also been reported as tuners of physical properties in TMDs − and of other layered materials. − Among such approaches, pressure proves to be an effective way to change the structural, electronic, and optical properties of MoS 2 . In this material, a structural phase transition from the hexagonal 2H c to 2H a structure is reported at ∼20 GPa, followed by a semiconducting to metallic electronic transition. − Such a critical pressure scales with the decreasing sample thickness, and for 1L-MoS 2 , the closing of the gap is predicted to be reached at ∼68 GPa .…”