This article reports a novel application of scanning Kelvin microscopy for exclusively revealing the distribution of a percolated conductive filler network in heterogeneous materials. The materials under investigation are carbon black and carbon nanotube-filled epoxies with a highly inhomogeneous conductivity distribution due to their fabrication. The Kelvin method is demonstrated to be especially suitable for resolving the resistive particle network in these kinds of composite materials with sample resistance levels in the megaohm range. Transmission optical microscopy reveals matches between the scanning Kelvin images and the sample morphologies, whereas the percolating backbone cannot be distinguished in the optical micrographs.
Subject classification: 78.20.Ci; 78.55.Hx; S10.15 Selective, low cost ultraviolet detectors with a sensitivity of up to 3 mA/W in the UVC energy range were fabricated by means of Eu 3+ -doped zinc borate glass (ZBG) fibers and Si-photodiodes. Europium-doped ZBG shows highly efficient emission (613 nm) from Eu 3+ by irradiation with high-energy UV light. The Eu 3+ -doped ZBG fiber converts the incoming UV light into visible light of 613 nm and guides it to a silicon photodiode. Eu 3+ -doped ZBG fibers Zn x B 1--x O 1.5--0.5x of varying composition (x = 0.33-0.52) were produced by the melt spinning method from glass melt in air atmosphere. The fibers were then connected to the silicon photodiode surface. The wavelength of maximum sensitivity of our detector is in the far ultraviolet and can be varied between 240 and 270 nm by changing the Zn content in the glass matrix.
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