Mfp 3d infinity afm

The topography image of the surface in the main text and supplementary materials was measured using Asylum Research MFP-3D Infinity AFM in tapping mode (resolution: 256 × 256 pixels). After 100 km of sliding between the graphite and DLC, we took the disk from the turntable and placed it under AFM. According to the mark made in advance, we found the location of the sliding track. We characterized a 10 μm × 10 μm square area with the sliding track as the center, as shown in Fig. 1e. Because the size of the graphite flake was 4 μm × 4 μm, the 10 μm × 10 μm zone covered the entire sliding track.
If wear occured, there would be defects at the bottom surface of the graphite flake which was in contact with DLC. Raman spectra are widely used to characterize graphitic materials and particularly sensitive to the defects in graphite [53 (link)]. When 100 km of contact sliding was finished, we turned over the graphite flake sample and characterized it using Raman spectra, as shown in Fig. 1d and Supplementary Fig. S5. The absence of D peak shows there are no defects appearing on the graphite sample, thus no wear has occurred.

All the SEM and EDS results are derived from the microscope (FEI, Quanta 450) integrated with the instrument (INCA Energy 200). The contact angles are measured by the goniometer (OCA25, Dataphysics). The crystallinity is characterized by the XRD (Rigaku Smartlab) and the Raman spectrometer (Perkinelmer Raman station 400F). The ferroelectricity is conducted on an Asylum Research MFP-3D Infinity AFM.

Optical absorption spectra were recorded with a ultraviolet–visible–near infrared spectrometer Agilent Cary 5000 measuring in transmission configuration. The spectrometer can measure absorbance up an optical density of 10. Single crystals of β- or γ-coronene were suspended in the sample beam path. Unpolarized light was shone perpendicular to the a–b plane of the unit cells. High-quality crystals with flat surfaces were carefully selected to avoid light scattering effects. The beam size was narrowed to half the lateral size of crystals. All absorption spectra were recorded at room temperature in air. Elastic moduli were determined using an Asylum Research MFP-3D Infinity AFM operating in AMFM viscoelastic imaging mode, using an AC160TS-R3 silicon tip (9±2 nm radius). Freshly cleaved mica was used as a calibration standard (measured at 178 GPa). Melting point determination was done using a TA-Instruments Q100 DSC with temperature ramp of 1 °C min⁻¹ between 35 and 460 °C with 2.2 mg of coronene hermetically sealed under a nitrogen atmosphere in an aluminium pan.