In this paper, the electrical transport and mechanical properties of Pt/ZnO Schottky nanocontacts have been studied simultaneously during the formation and rupture of the nanocontacts. By combining multidimensional conducting scanning force spectroscopy with appropriated data processing, the physical relevant parameters (the ideality factor, the Schottky barrier height, and the rupture voltage) are obtained. It has been found that the transport curves strongly depend on the loading force. For loading forces higher than a threshold value, the transport characteristics are similar to those of large-area Schottky contact, while below this threshold deviations from strictly thermionic emission are detected. Above the threshold, stable and reproducible Pt/ZnO nanocontacts with ideality factors of about 2 and Schottky barrier heights of around 0.45 eV have been obtained.
Frequency modulation dynamic scanning force microscopy has been implemented in ambient conditions using low oscillation amplitudes (<1 nm) to simultaneously record not only topographic but also additional channels of information, in particular contact potential images. The performance of this mode as compared to the conventional amplitude modulation mode is analyzed in detail using a biological molecule, turning yellow mosaic virus RNA, as the model sample. On the basis of scanning force microscopy imaging as well as spectroscopy experiments, we find that for such very small samples the frequency modulation mode is superior since it can be operated with smaller tip-sample interaction, smaller effective tip-sample distance and lower forces. Combined with Kelvin probe microscopy it results not only in considerably higher electrostatic resolution, but also in correct quantitative values for the contact potential as compared to traditional amplitude modulation scanning force microscopy.
Mixtures of poly(3‐octylthiophene) (P3OT) with graphite nanoparticles have been investigated by scanning force microscopy (SFM) techniques. The morphology as well as the mechanical and electrical properties of the blends has been characterized at the nanoscale level as a function of the carbon nanoparticle content in the blend. An increase in the concentration of carbon nanoparticles results in an increase in the surface roughness of the blend and the appearance of distinct regions with well‐defined electrical and mechanical properties. At intermediate concentrations (5–10 wt % of carbon nanoparticles), the samples show pure P3OT regions, as well as round regions containing a mixture of the polymer and carbon nanoparticles, while at higher concentrations (> 15 wt %), the entire sample is composed of this mixture. The interface between the two regions has been studied by electrostatic scanning force microscopy (ESFM) as a function of the applied tip–sample voltage. ESFM provides evidence for the creation of new electronic states at the heterojunction. The observed results can be qualitatively explained in terms of the electronic properties of the individual molecular components, P3OT, functionalized graphite nanoparticles, and their corresponding heterojunction. The implications of these results for organic polymer solar cells are also discussed.
1Crop protection residual plastic films are a growing environmental problem which 2 requires efficient solutions. Their suitability as matrices for obtaining sustainable eco-3 composites reinforced with industrially-sourced residual natural fibers was investigated 4 in order to boost their recovery and prevent waste generation. The analysis of the 5 studied residual agricultural plastics revealed that they are low density polyethylene still 6 containing significant amounts of ethylene-vinyl acetate (2.5 to 4.5 wt%). A pilot-plant 7 extrusion-compounding technology was applied to a selected recycled plastic from 8 residual agricultural films and the residual cellulose fibers for obtaining the eco-9composites. The effects of cellulose-fiber content and a selected maleic anhydride-10 modified polyethylene coupling agent on the properties and interfacial adhesion of the 11 eco-composites were investigated. By using micromechanical models, scientific data of 12 the intrinsic modulus and strength of the Eucalyptus Globulus residual fibers, hitherto 13 scarcely available in literature, were found to be 16.4 GPa and 180 MPa, respectively, 14 thus revealing their suitability as cost-effective reinforcement. Tensile modulus and 15 strength of the eco-composites were up to 667 % and 70 % greater than those of the neat 16 agricultural recycled plastic, the latter due to the enhanced compatibility provided by 17 the ethylene-vinyl acetate found. When the coupling agent was added, tensile and 18 flexural strengths increased up to a maximum of 20.26 MPa and 23.96 MPa, 19 respectively. Property variations were found to be due to the fiber length reduction and 20 the interfacial adhesion improvement caused by the coupling agent as well as to its 21 plasticizing effect. The properties achieved revealed the suitability of the eco-22 composites for their immediate application in the production of numerous 23 environmentally sustainable and cost-effective end-products from the aforementioned 24 wastes. 25 3
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