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Mechanoluminescence of a composite based on polymethylmethacrylate and fine-disperse powder of SrAl <sub/>2</sub> O <sub/>4</sub> :(Eu <sup>2+</sup> , Dy <sup>3+</sup> ) phosphor
摘要： The paper deals with photoluminescence and deformation (mechanoluminescence) of a composite material based on fine-disperse powder of phosphor SrAl2O4:(Eu2+, Dy3+) and polymethylmethacrylate that is transparent in the visible region. The luminescent (sensory) layer responsive to mechanical action was formed in the surface layer of the polymethylmethacrylate. To excite of photoluminescence the short pulses of a nanosecond laser were used. Mechanoluminescence was excited by the short acoustic impulses generated by a nanosecond laser. New information about the energy levels of impurities was obtained.
关键词： Dy3+),SrAl2O4:(Eu2+,composite material,polymethylmethacrylate,mechanoluminescence,photoluminescence
更新于2025-09-11 14:15:04
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Synthesis of CdSe/ZnS@HPU-2 composites for highly sensitive and multicolor florescence response to Fe3+
摘要： A composite material based dual-emission probe for Fe3+ was prepared by the hybridization of a three-dimensional framework with CdSe/ZnS quantum dots (QDs)-doped silica nanoparticles. The obtained probe showed characteristic fluorescence emissions of CdSe/ZnS QDs (red) and Cd-metal-organic framework (MOF, blue) under a single exciation wavelength. Upon the detection of Fe3+, only the fluorescence of Cd-MOF was quenched, whereas the red fluorescence of CdSe/ZnS QDs particles was mostly reserved. Consequently, the variation of the two fluorescence intensity ratios displays a continuous color change from blue to red upon exposure to different amounts of Fe3+ ions, which can be easily observed under a UV lamp.
关键词： dual-emission probe,Fe3+,composite material
更新于2025-09-10 09:29:36
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Anisotropic conductivity of Cellulose-PEDOT:PSS composite materials studied with a generic 3D four-point probe tool
摘要： The conductive polymer poly(3,4-ethylenedioxythiphene):poly(styrenesulfonate) (PEDOT:PSS) is widely used in organic electronics and printed electronics due to its excellent electronic and ionic conductivity. PEDOT:PSS films exhibit anisotropic conductivities originating from the interplay of film deposition processes and chemical structure. The previous studies found that high boiling point solvent treated PEDOT:PSS exhibits an anisotropy of 3 to 4 orders magnitude. Even though both the in-plane and out-of-plane conductivities are important for the device performance, the out-of-plane conductivity is rarely studied due to the complexity with the experiment procedure. Cellulose-based paper or films can also exhibit anisotropic behavior due to the combination of their intrinsic fibric structure and film formation process. We have previously developed a conductive paper based on PEDOT:PSS and cellulose which could be used as the electrodes in energy storage devices. In this work we developed a novel measurement set-up for studying the anisotropy of the charge transport in such composite materials. A tool with two parallel plates mounted with spring loaded probes was constructed enabling probing both lateral and vertical directions and resistances from in-plane and out-of-plane directions to be obtained. The measurement results were then input and analyzed with a model based on a transformation method developed by Montgomery, and thus the in-plane and out-of-plane conductivities could be detangled and derived. We also investigated how the conductivity anisotropy depends on the microstructure of the cellulose template onto which the conductive polymer self-organizes. We show that there is a relatively small difference between the in-plane and out-of-plane conductivities which is attributed to the unique 3D-structure of the composites. This new knowledge gives a better understanding of the possibilities and limitations for using the material in electronic and electrochemical devices.
关键词： Cellulose,PEDOT:PSS,composite material,anisotropic conductivity,four-point probe
更新于2025-09-04 15:30:14