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Chanisa Nawanil Worawut Makcharoen Krittanat Khaosa-Ard Tosapol Maluangnont Wanwilai Vittayakorn Don Isarakorn 《组合铁电体》2019,195(1):46-57
AbstractThis study explored the preparation and electrical properties of 0–3 barium titanate/polydimethylsiloxane nanocomposites by dispersing barium titanate nanoparticles (BaTiO3; BT) into the polydimethylsiloxane (PDMS) matrix phase. The effect of barium titanate nanoparticles on electrical properties has been investigated systematically, and the relative permittivity of nanocomposites was found to increase significantly with increasing barium titanate content. Different theoretical models were used to predict the dielectric constant of these composites and compare their experimental value with the theoretical value in order to find an appropriate equation. The result indicated that the dielectric properties of composites are influenced not only by relative permittivity of the components but also dependence on interactions between ceramics and polymers. Furthermore, the preparation and dielectric properties of BT/PDMS nanocomposites modified with carbon nanotube (CNT) were also studied. The dielectric results demonstrate that adding CNT can enhance the relative permittivity of the BT/PDMS composite via improvement of dispersion and distribution of the BT nanoparticles in the PDMS matrix phase. Moreover, the electrical outputs from the BT/PDMS/CNT nanocomposites generator were measured under periodic knocking. The nanocomposites innovatively expand the feasibility of self-powered energy systems for smart sensor and energy harvesting applications. 相似文献
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Sanna Arpiainen Fredrik Jonsson James R. Dekker Gudrun Kocher Worawut Khunsin Clivia M. Sotomayor Torres Jouni Ahopelto 《Advanced functional materials》2009,19(8):1247-1253
A scalable method for site‐selective, directed self‐assembly of colloidal opals on topologically patterned substrates is presented. Here, such substrate contains optical waveguides which couple to the colloidal crystal. The site‐selectivity is achieved by a capillary network, whereas the self‐assembly process is based on controlled solvent evaporation. In the deposition process, a suspension of colloidal microspheres is dispensed on the substrate and driven into the desired crystallization sites by capillary flow. The method has been applied to realize colloidal crystals from monodisperse dielectric spheres with diameters ranging from 290 to 890 nm. The method can be implemented in an industrial wafer‐scale process. 相似文献
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Worawut Khunsin Gudrun Kocher Sergei G. Romanov Clivia M. Sotomayor Torres 《Advanced functional materials》2008,18(17):2471-2479
This work is devoted to the quantitative evaluation of the lattice ordering of opal films. Assembling colloidal crystals in a moving meniscus under random noise agitation produced opal films with generically the same lattice but different disorders. The lattice ordering is quantified by the magnitudes of harmonics in the Fourier transforms of (i) the scanning electron microscopy images to address the in‐plane lattice ordering and (ii) rotation diagrams of the optical transmission to address the regularity of crystal planes. In prepared opals, the strong deviation of the lattice from the face‐centered cubic symmetry is demonstrated. We find uneven lattice responses to changing the growth conditions, e.g., the 30% improvement of the hexagonal lattice ordering in the (111) growth plane accompanied by a ten‐time better ordering of (220) planes as a result of noise agitation. The suggested approach to characterize crystalline quality of the lattice is a general methodology that can be applied to the analysis of other three‐dimensional photonic crystals. 相似文献
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Khunsin W Brian B Dorfmüller J Esslinger M Vogelgesang R Etrich C Rockstuhl C Dmitriev A Kern K 《Nano letters》2011,11(7):2765-2769
In nanoscopic systems, size, geometry, and arrangement are the crucial determinants of the light-matter interaction and resulting nanoparticles excitation. At optical frequencies, one of the most prominent examples is the excitation of localized surface plasmon polaritons, where the electromagnetic radiation is coupled to the confined charge density oscillations. Here, we show that beyond direct near- and far-field excitation, a long-range, indirect mode of particle excitation is available in nanoplasmonic systems. In particular, in amorphous arrays of plasmonic nanodiscs we find strong collective and coherent influence on each particle from its entire active neighborhood. This dependency of the local field response on excitation conditions at distant areas brings exciting possibilities to engineer enhanced electromagnetic fields through controlled, spatially configured illumination. 相似文献
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Worawut Makcharoen Jerapong Tontrakoon Gobwute Rujijanagul David P. Cann Tawee Tunkasiri 《Ceramics International》2012
In this study, CaCu3Ti4O12 (CCTO) ceramics were doped with cesium and cerium atoms to possibly improve the electrical properties of these widely used ceramics. In all cases, pure phase perovskites were produced where cesium doping enhanced the grain growth and cerium doping produced grain growth inhibition. The cesium doping showed an improvement in loss tangent performance, in contrast to the cerium doping which showed a negative result. A high dielectric constant >15,000 with a dielectric loss lower than 0.06 was observed for cesium 2.0 mol% doped at high frequencies. These results were related to the change in microstructure and the properties of grain boundary after doping. 相似文献
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In this work, we have reported microstructures and the dielectric properties of CaCu3Ti4O12 (CCTO) ceramics doped with different proportions of TeO2 dopant (mol%, x=0, 0.5%, 1.0%, 2.0%). The pure and tellurium doping CCTO ceramics were prepared by a conventional solid-state reaction method and the effects of TeO2 doping on the electrical properties and microstructures of these ceramics were investigated. XRD analysis confirmed the formation of single-phase material in samples. Scanning electron microscopy (SEM) is used in the micro structural studies of the specimens, which showed that TeO2 doping can reduce the mean grain size and increasing size of an abnormal grain growth. Lattice parameter increases slightly with tellurium doping in CCTO, the dielectric constant reached a value as high as 18,000 (at 1 kHz) at a tellurium-doping concentration of 2.0 mol% and showed temperature stability at high frequency. The loss tangent of Te-doped CCTO ceramics was less than 0.05 at 1 kHz region below 105 °C. The loss tangent properties could be interpreted by the internal barrier layer capacitor model and the impedance measurement data. 相似文献
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Worawut Khunsin Andreas Amann Gudrun Kocher‐Oberlehner Sergei G. Romanov Saroj Pullteap Han Cheng Seat Eoin P. O'Reilly Rudolf Zentel Clivia M. Sotomayor Torres 《Advanced functional materials》2012,22(9):1812-1821
An improvement of the crystal quality of opal films self‐assembled from polymer spheres in a moving meniscus using the agitation by white noise acoustic vibrations is demonstrated. A tenfold higher ordering of a hexagonal sphere packing in the (111) plane is achieved. This crystallization method, the mechanism of which is described in terms of the stochastic resonance, is a contrast to the widely used approach based on maintaining equilibrium conditions during the crystallization process. The precise quantification of the incremental lattice order improvement as a function of acoustic noise intensity is achieved by calculating the probability of finding an opposite partner for each sphere in the lattice. This method is examined against conventional and established techniques such as Fourier transforms and translational and bond‐orientational correlation functions, and its advantages are demonstrated. Rotational symmetry analysis of diffraction resonances in measured and calculated optical transmission spectra as a function of the azimuth lattice orientation are carried out to confirm that the surface ordering translates into the bulk ordering of high index crystal planes, which are most sensitive to disorder. 相似文献
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We study a single-item, single-site, periodic-review inventory system with negligible fixed ordering costs. The supplier to this system is not entirely reliable, such that each order is a Bernoulli trial, meaning that, with a given probability, the supplier delivers the current order and any accumulated backorders at the end of the current period, resulting in a Geometric distribution for the actual resupply lead time. We develop a recursive expression for the steady-state probability vector of a discrete-time Markov process (DTMP) model of this imperfect-supply inventory system. We use this recursive expression to prove the convexity of the inventory system objective function, and also to prove the optimality of our computational procedure for finding the optimal base-stock level. We present a service-constrained version of the problem and show how the computation of the optimal base-stock level using our DTMP method, incorporating the explicit distribution of demand over the lead time plus review (LTR) period, compares to approaches in the literature that approximate this distribution. We also show that the version of the problem employing an explicit penalty cost can be solved in closed-form for the optimal base-stock level for two specific period demand distributions, and we explore the behavior of the optimal base-stock level and the corresponding optimal service level under various values of the problem parameters. 相似文献