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Journal articles on the topic 'Carbone nanotubes microwave device'
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Tripon-Canseliet, Charlotte, Stephane Xavier, Yifeng Fu, Jean-Paul Martinaud, Afshin Ziaei, and Jean Chazelas. "Experimental Microwave Complex Conductivity Extraction of Vertically Aligned MWCNT Bundles for Microwave Subwavelength Antenna Design." Micromachines 10, no. 9 (August 27, 2019): 566. http://dx.doi.org/10.3390/mi10090566.
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This paper reports the extraction of electrical impedance at microwave frequencies of vertically aligned multi-wall carbon nanotubes (VA MWCNT) bundles/forests grown on a silicon substrate. Dedicated resonating devices were designed for antenna application, operating around 10 GHz and benefiting from natural inductive/capacitive behavior or complex conductivity in the microwave domain. As obtained from S-parameters measurements, the capacitive and inductive behaviors of VA MWCNT bundles were deduced from device frequency resonance shift.
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Liu, Jih-Hsin, and Yao-Sheng Huang. "Development of Microwave Filters with Tunable Frequency and Flexibility Using Carbon Nanotube Paper." Nanomaterials 13, no. 18 (September 5, 2023): 2497. http://dx.doi.org/10.3390/nano13182497.
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This study aims to exploit the distinctive properties of carbon nanotube materials, which are particularly pronounced at the microscopic scale, by deploying fabrication techniques that allow their features to be observed macroscopically. Specifically, we aim to create a semiconductor device that exhibits flexibility and the ability to modulate its electromagnetic wave absorption frequency by means of biasing. Initially, we fabricate a sheet of carbon nanotubes through a vacuum filtration process. Subsequently, phosphorus and boron elements are separately doped into the nanotube sheet, enabling it to embody the characteristics of a PN diode. Measurements indicate that, in addition to the fundamental diode’s current–voltage relationship, the device also demonstrates intriguing transmission properties under the TEM mode of electromagnetic waves. It exhibits a frequency shift of approximately 2.3125 GHz for each volt of bias change. The final result is a lightweight and flexible carbon-based semiconductor microwave filter, which can conform to curved surfaces. This feat underscores the potential of such materials for innovative and effective electromagnetic wave manipulation.
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BURKE, P. J., C. RUTHERGLEN, and Z. YU. "SINGLE-WALLED CARBON NANOTUBES: APPLICATIONS IN HIGH FREQUENCY ELECTRONICS." International Journal of High Speed Electronics and Systems 16, no. 04 (December 2006): 977–99. http://dx.doi.org/10.1142/s0129156406004119.
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In this paper, we review the potential applications of single-walled carbon nanotubes in three areas: passives (interconnects), actives (transistors), and antennas. In the area of actives, potential applications include transistors for RF and microwave amplifiers, mixers, detectors, and filters. We review the experimental state of the art, and present the theoretical predictions (where available) for ultimate device performance. In addition, we discuss fundamental parameters such as dc resistance as a function of length for individual, single-walled carbon nanotubes.
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Koshikawa, Yusuke, Ryo Miyashita, Takuya Yonehara, Kyoka Komaba, Reiji Kumai, and Hiromasa Goto. "Conducting Polymer Metallic Emerald: Magnetic Measurements of Nanocarbons/Polyaniline and Preparation of Plastic Composites." C 8, no. 4 (November 4, 2022): 60. http://dx.doi.org/10.3390/c8040060.
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Synthesis of polyaniline in the presence of fullerene nanotubes (nanocarbons) in water was carried out with oxidative polymerization. The surface of the sample showed metallic emerald green color in bulk like the brilliance of encrusted gemstones. The composite showed unique magnetic behavior, such as microwave power-dependent magnetic resonance as magnetic spin behavior and macroscopic paramagnetism with a maximum χ value at room temperature evaluated with superconductor interference device. Surface structure of the composite was observed with optical microscopy, circular polarized differential interference contrast optical microscopy, scanning electron microscopy, and electron probe micro analyzer. Polymer blends consisting of polyaniline, nano-carbons, and hydroxypropylcellulose or acryl resin with both conducting polymer and carbon characters were prepared, which can be applied for electrical conducting plastics. The combination of conducting polymer and nano-carbon materials can produce new electro-magneto-active soft materials by forming a composite. This paper reports evaluation of magnetic properties as a new point of nanocarbon and conducting polymer composite.
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Chen, Ying-Chu, Yu-Kuei Hsu, Yan-Gu Lin, Li-Chyong Chen, and Kuei-Hsien Chen. "Spontaneous Synthesis and Electrochemical Characterization of NanostructuredMnO2on Nitrogen-Incorporated Carbon Nanotubes." International Journal of Electrochemistry 2012 (2012): 1–10. http://dx.doi.org/10.1155/2012/475417.
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This paper investigated the layered manganese dioxide with hydrate (MnO2⋅xH2O) deposits onto nitrogen-containing carbon nanotube (CNxNTs) as a hierarchical electrode for an energy-storage device. The dense and entangled CNxNTs were directly grown by microwave plasma-enhanced chemical vapor deposition (MPECVD) on a carbon cloth (CC), and subsequently used as a current collector. By controlling the pH value of KMnO4precursor solution, and incorporating nitrogen into CNTs as a reducing agent, the MnO2thin layer was uniformly fabricated on the CNxNTs at room temperature by using a spontaneous reduction method. The role of incorporation nitrogen is not only capable of creating active sites on the CNT surface, but can also donate electrons to reduceMnO4-to MnO2spontaneously. From the measurements of cyclic voltammograms and galvanostatic charge/discharge, MnO2/CNxNTs/CC composite electrodes illustrated excellent specific capacitance of 589.1 Fg-1. The key factor for high performance could be attributed to the thin-layered MnO2nanostructure, which resulted in the full utilization of MnO2deposits. Hence, the hierarchically porous MnO2/CNxNTs/CC electrodes exhibited excellent capacitive behavior for electrochemical capacitor application.
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Motshekga, Sarah C., Sreejarani K. Pillai, Suprakas Sinha Ray, Kalala Jalama, and Rui W. M. Krause. "Recent Trends in the Microwave-Assisted Synthesis of Metal Oxide Nanoparticles Supported on Carbon Nanotubes and Their Applications." Journal of Nanomaterials 2012 (2012): 1–15. http://dx.doi.org/10.1155/2012/691503.
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The study of coating carbon nanotubes with metal/oxides nanoparticles is now becoming a promising and challenging area of research. To optimize the use of carbon nanotubes in various applications, it is necessary to attach functional groups or other nanostructures to their surface. The combination of the distinctive properties of carbon nanotubes and metal/oxides is expected to be applied in field emission displays, nanoelectronic devices, novel catalysts, and polymer or ceramic reinforcement. The synthesis of these composites is still largely based on conventional techniques, such as wet impregnation followed by chemical reduction of the metal nanoparticle precursors. These techniques based on thermal heating can be time consuming and often lack control of particle size and morphology. Hence, there is interest in microwave technology recently, where using microwaves represents an alternative way of power input into chemical reactions through dielectric heating. This paper covers the synthesis and applications of carbon-nanotube-coated metal/oxides nanoparticles prepared by a microwave-assisted method. The reviewed studies show that the microwave-assisted synthesis of the composites allows processes to be completed within a shorter reaction time with uniform and well-dispersed nanoparticle formation.
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Mathur, A., S. S. Roy, and J. A. McLaughlin. "Transferring vertically aligned carbon nanotubes onto a polymeric substrate using a hot embossing technique for microfluidic applications." Journal of The Royal Society Interface 7, no. 48 (February 10, 2010): 1129–33. http://dx.doi.org/10.1098/rsif.2009.0520.
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We explored the hot embossing method for transferring vertically aligned carbon nanotubes (CNTs) into microfluidic channels, fabricated on poly-methyl-methacrylate (PMMA). Patterned and unpatterned CNTs were synthesized by microwave plasma-enhanced chemical vapour deposition on silicon to work as a stamp. For hot embossing, 115°C and 1 kN force for 2 min were found to be the most suitable parameters for the complete transfer of aligned CNTs on the PMMA microchannel. Raman and SEM studies were used to analyse the microstructure of CNTs before and after hot embossing. The PMMA microparticles with dimensions (approx. 10 µm in diameter) similar to red blood cells were successfully filtered using laminar flow through these microfluidic channels. Finally, a microfluidic-based point-of-care device for blood filtration and detection of bio-molecules is drawn schematically.
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Mani, Veerappan, T. S. T. Balamurugan, and Sheng-Tung Huang. "Rapid One-Pot Synthesis of Polydopamine Encapsulated Carbon Anchored with Au Nanoparticles: Versatile Electrocatalysts for Chloramphenicol and Folic Acid Sensors." International Journal of Molecular Sciences 21, no. 8 (April 19, 2020): 2853. http://dx.doi.org/10.3390/ijms21082853.
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Designing and engineering nanocomposites with tailored physiochemical properties through teaming distinct components is a straightforward strategy to yield multifunctional materials. Here, we describe a rapid, economical, and green one-pot microwave synthetic procedure for the preparation of ternary nanocomposites carbon/polydopamine/Au nanoparticles (C/PDA/AuNPs; C = carbon nanotubes (CNTs), reduced graphene oxide (rGO)). No harsh reaction conditions were used in the method, as are used in conventional hydrothermal or high-temperature methods. The PDA unit acts as a non-covalent functionalizing agent for carbon, through π stacking interactions, and also as a stabilizing agent for the formation of AuNPs. The CNTs/PDA/AuNPs modified electrode exhibited excellent electrocatalytic activity to oxidize chloramphenicol and the resulting sensor exhibited a low detection limit (36 nM), wide linear range (0.1–534 μM), good selectivity (against 5-fold excess levels of interferences), appreciable reproducibility (3.47%), good stability (94.7%), and practicality (recoveries 95.0%–98.4%). Likewise, rGO/PDA/AuNPs was used to fabricate a sensitive folic acid sensor, which exhibits excellent analytical parameters, including wide linear range (0.1–905 μM) and low detection limit (25 nM). The described synthetic route includes fast reaction time (5 min) and a readily available household microwave heating device, which has the potential to significantly contribute to the current state of the field.
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Maratta Martínez, Ariel, Sandra Vázquez, Rodolfo Lara, Luis Dante Martínez, and Pablo Pacheco. "Selenium analysis by an integrated microwave digestion-needle trap device with hydride sorption on carbon nanotubes and electrothermal atomic absorption spectrometry determination." Spectrochimica Acta Part B: Atomic Spectroscopy 140 (February 2018): 22–28. http://dx.doi.org/10.1016/j.sab.2017.12.001.
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Mathur, A., Tuhin Maity, Shikha Wadhwa, B. Ghosh, Sweety Sarma, Sekhar C. Ray, Bhaskar Kaviraj, Susanta S. Roy, and Saibal Roy. "Magnetic properties of microwave-plasma (thermal) chemical vapour deposited Co-filled (Fe-filled) multiwall carbon nanotubes: comparative study for magnetic device applications." Materials Research Express 5, no. 7 (July 4, 2018): 076101. http://dx.doi.org/10.1088/2053-1591/aacddb.
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He, Liming, Hongda Xu, Yang Cui, Jian Qi, Xiaolong Wang, and Quan Jin. "Co-Doped Porous Carbon/Carbon Nanotube Heterostructures Derived from ZIF-L@ZIF-67 for Efficient Microwave Absorption." Molecules 29, no. 11 (May 21, 2024): 2426. http://dx.doi.org/10.3390/molecules29112426.
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Carbon-based magnetic metal composites derived from metal–organic frameworks (MOFs) are promising materials for the preparation of broadband microwave absorbers. In this work, the leaf-like co-doped porous carbon/carbon nanotube heterostructure was obtained using ZIF-L@ZIF-67 as precursor. The number of carbon nanotubes can be controlled by varying the amount of ZIF-67, thus regulating the dielectric constant of the sample. An optimum reflection loss of −42.2 dB is attained when ZIF-67 is added at 2 mmol. An effective absorption bandwidth (EAB) of 4.8 GHz is achieved with a thickness of 2.2 mm and a filler weight of 12%. The excellent microwave absorption (MA) ability is generated from the mesopore structure, uniform heterogeneous interfaces, and high conduction loss. The work offers useful guidelines to devise and prepare such nanostructured materials for MA materials.
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Sohn, Minjeong, Min-Su Kim, Byeong-Kwon Ju, and Tae-Ik Lee. "Flexible Bonding of Polymer Substrates By Microwave Heating of Carbon Nanotubes." ECS Meeting Abstracts MA2022-02, no. 8 (October 9, 2022): 641. http://dx.doi.org/10.1149/ma2022-028641mtgabs.
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Recently, as research on developing electronic devices for simultaneous implementation of flexibility and conductivity has been continuously conducted, ensuring stable and high reliability of devices in preparation for various mechanical deformation is becoming important. When a physical force such as bending, twisting, or folding is applied, the bonding area between two substrates should ensure stability due to high stress generation. Epoxy resin materials used as standard adhesive agents have brittleness due to the nature of the material, and are weak in terms of flexibility due to increased bonding thickness due to high temperature hardening. In addition, it is difficult to apply as a bonding material in consideration of thermal deformation of the polymer substrate exposed to high temperatures during the process. To improve both flexibility and durability against fatigue deformation, Flexible bonding process is required without adhesive such as epoxy resin with poor brittleness. Surface activation bonding technologies by ion beams and vacuum ultraviolet rays have been developed in previous studies, bonding between plastic substrates by activating thin metal films surface of adhesive layer with ion beam or improving adhesive force by direct-UV radiation on the surface of the polymer substrate. In this study, a flexible bonding process between polymer substrates was developed by heating carbon nanotubes (CNTs) through microwave irradiation. High microwave absorption properties of CNT lead to heat dissipation behavior and light emission characteristics. Heat transfer mechanism of CNT applied to CNT-polymer composites, CNT electrodes fields and has been microwave assisted purification. By utilizing the microwave heating effect, we selected CNT materials for flexible substrates. Multi-walled carbon nanotubes (MWNTs) were coated on a bonded PET polymer substrate and then local heating was performed by microwaves to induce mechanical entanglement between the CNTs and the PET. In the bonding process, the output power of the microwave was adjusted to 600,800 and 1000 Watt, and the bonding strength was evaluated by quantifying the bonding strength was evaluated. For the analysis of the bonding mechanism in the area where mechanical entanglement took place, the CNT-PET bonding interface was analyzed through electron scanning microscope (SEM) measurement, and further analysis was performed for each process condition. In addition, a fracture mechanism analysis that occurred at the junction was performed after the overlapping shear strength test. Acknowledgments This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2020M3H4A3106413, Development of Evaluation Method for Mechanical Deformation of Micro-joints in Micro-LED Module) Figure 1
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Milne, W. I., K. B. K. Teo, G. A. J. Amaratunga, R. Lacerda, P. Legagneux, G. Pirio, V. Semet, and V. Thien Binh. "Aligned carbon nanotubes/fibers for applications in vacuum microwave devices." Current Applied Physics 4, no. 5 (August 2004): 513–17. http://dx.doi.org/10.1016/j.cap.2004.02.005.
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Sidi Salah, Lakhdar, Mohamed Chouai, Yann Danlée, Isabelle Huynen, and Nassira Ouslimani. "Simulation and Optimization of Electromagnetic Absorption of Polycarbonate/CNT Composites Using Machine Learning." Micromachines 11, no. 8 (August 15, 2020): 778. http://dx.doi.org/10.3390/mi11080778.
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Electronic devices that transmit, distribute, or utilize electrical energy create electromagnetic interference (EMI) that can lead to malfunctioning and degradation of electronic devices. EMI shielding materials block the unwanted electromagnetic waves from reaching the target material. EMI issues can be solved by using a new family of building blocks constituted of polymer and nanofillers. The electromagnetic absorption index of this material is calculated by measuring the “S-parameters”. In this article, we investigated the use of artificial intelligence (AI) in the EMI shielding field by developing a new system based on a multilayer perceptron neural network designed to predict the electromagnetic absorption of polycarbonate-carbon nanotubes composites films. The proposed system included 15 different multilayer perception (MLP) networks; each network was specialized to predict the absorption value of a specific category sample. The selection of appropriate networks was done automatically, using an independent block. Optimization of the hyper-parameters using hold-out validation was required to ensure the best results. To evaluate the performance of our system, we calculated the similarity error, precision accuracy, and calculation time. The results obtained over our database showed clearly that the system provided a very good result with an average accuracy of 99.7997%, with an overall average calculation time of 0.01295 s. The composite based on polycarbonate−5 wt.% carbon nanotube was found to be the ultimate absorber over microwave range according to Rozanov formalism.
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Korotcenkov, Ghenadii, Nikolay P. Simonenko, Elizaveta P. Simonenko, Victor V. Sysoev, and Vladimir Brinzari. "Paper-Based Humidity Sensors as Promising Flexible Devices, State of the Art, Part 2: Humidity-Sensor Performances." Nanomaterials 13, no. 8 (April 16, 2023): 1381. http://dx.doi.org/10.3390/nano13081381.
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This review article covers all types of paper-based humidity sensor, such as capacitive, resistive, impedance, fiber-optic, mass-sensitive, microwave, and RFID (radio-frequency identification) humidity sensors. The parameters of these sensors and the materials involved in their research and development, such as carbon nanotubes, graphene, semiconductors, and polymers, are comprehensively detailed, with a special focus on the advantages/disadvantages from an application perspective. Numerous technological/design approaches to the optimization of the performances of the sensors are considered, along with some non-conventional approaches. The review ends with a detailed analysis of the current problems encountered in the development of paper-based humidity sensors, supported by some solutions.
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Pacchini, Sébastien, David Dubuc, Emmanuel Flahaut, and Katia Grenier. "Double-walled carbon nanotube-based polymer composites for electromagnetic protection." International Journal of Microwave and Wireless Technologies 2, no. 5 (October 2010): 487–95. http://dx.doi.org/10.1017/s1759078710000668.
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In this paper, we present a microwave absorber based on carbon nanotubes (CNT) dispersed inside a BenzoCycloButen® (BCB) polymer. The high aspect ratio and remarkable conductive characteristics of CNT give rise to good absorbing properties for electromagnetic protecting in microelectronic devices with very low concentration. In this article, nanocomposites are prepared using a solution-mixing method and are then evaluated and modeled by means of coplanar test structures. First, CNT concentrations are quantified by image processing. The nanocomposites implemented with coplanar test waveguides are then characterized using a vector network analyzer from 40 MHz to 20 GHz. An algorithm is developed to calculate the propagation constant “γ”, attenuation constant “α”, and relative effective complex permittivity (ɛreff = ɛreff′ − jɛreff″) for each CNT concentration. The extracted effective parameters are verified using the electromagnetic FEM-based Ansoft's® high frequency structure simulator (HFSS). Power absorption (PA) of 7 dB at 15 GHz is obtained with only 0.37 weight percent of CNT concentration in the polymer matrix. The resulting engineerable and controllable composite provides consequently a novel degree of freedom to design and optimize innovative microwave components.
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Ding, Er Xiong, Hong Zhang Geng, Li He Mao, Wen Yi Wang, Yan Wang, Zhi Jia Luo, Jing Wang, and Hai Jie Yang. "Recent Research Progress of Carbon Nanotube Arrays Prepared by Plasma Enhanced Chemical Vapor Deposition Method." Materials Science Forum 852 (April 2016): 308–14. http://dx.doi.org/10.4028/www.scientific.net/msf.852.308.
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Preparing carbon nanotube (CNT) arrays by plasma enhanced chemical vapor deposition (PECVD) method can dramatically reduce the deposition temperature, which makes it possible for in-situ fabrication of CNT-based nanoelectronic devices. In this paper, up to date research progress of CNT arrays prepared by PECVD method was presented, including radio frequency PECVD, direct current PECVD and microwave PECVD. Then, morphology and quality of CNT arrays were compared. In the end, we analyzed the possible challenges encountered through CNT array preparation by PECVD method at the moment and in the future.
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Al-Rabadi, Anas, and Marwan Mousa. "Field emission - based many-valued processing using carbon nanotube controlled switches - Part 2: Architecture effectuation." Facta universitatis - series: Electronics and Energetics 25, no. 1 (2012): 15–30. http://dx.doi.org/10.2298/fuee1201015a.
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A novel field emission Carbon Nanotube (CNT) - based controlled switch is introduced in the second part of the article. For the architecture effectuation of the new CNT field emission - based switching device, four field emission tubes having single CNT as emitters were previously tested and compared to a tungsten-tip tube, and the corresponding Fowler-Nordheim analysis was performed. Measurements conducted with the CNT suggested that mixer current could be 30 times greater if either SWCNT or MWCNT were used in place of metal emitters, increasing the microwave output power by 30 dB. Laser radiation was utilized to increase field emission current from a cathode with a dense field of CNT by a factor of 18. The extension of the new device from the two-valued to the general mvalued case is introduced, and the implementation of many-valued Galois circuits and systems is also shown.
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Jirimali, Harishchandra, Jyoti Singh, Rajamouli Boddula, Jung-Kul Lee, and Vijay Singh. "Nano-Structured Carbon: Its Synthesis from Renewable Agricultural Sources and Important Applications." Materials 15, no. 11 (June 2, 2022): 3969. http://dx.doi.org/10.3390/ma15113969.
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Carbon materials are versatile in nature due to their unique and modifiable surface and ease of production. Nanostructured carbon materials are gaining importance due to their high surface area for application in the energy, biotechnology, biomedical, and environmental fields. According to their structures, carbon allotropes are classified as carbon nanodots, carbon nanoparticles, graphene, oxide, carbon nanotubes, and fullerenes. They are synthesized via several methods, including pyrolysis, microwave method, hydrothermal synthesis, and chemical vapor deposition, and the use of renewable and cheaper agricultural feedstocks and reactants is increasing for reducing cost and simplifying production. This review explores the nanostructured carbon detailed investigation of sources and their relevant reports. Many of the renewable sources are covered as focused here, such as sugar cane waste, pineapple, its solid biomass, rise husk, date palm, nicotine tabacum stems, lapsi seed stone, rubber-seed shell, coconut shell, and orange peels. The main focus of this work is on the various methods used to synthesize these carbon materials from agricultural waste materials, and their important applications for energy storage devices, optoelectronics, biosensors, and polymer coatings.
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Lu, Bin, J. X. Liu, H. W. Zhu, and X. H. Jiao. "SiC Nanowires Synthesized by Microwave Heating." Materials Science Forum 561-565 (October 2007): 1413–16. http://dx.doi.org/10.4028/www.scientific.net/msf.561-565.1413.
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Large-scale silicon carbide nanowires are prepared by pure silicon powder and phenolic resin, which are mixed, molded, carbonizated, and then subjected to the microwave heating with a rate of 10oC/min between 1300 and 1400oC in the static argon atmosphere for 0.5~2h. The patterns of the SiC nanowires are characterized by means of SEM, the composition of the samples are determined through EDX. The prepared nanowires have the diameters between 20 to 100nm. The current results imply that liquid silicon can act as a catalyzer during the formation of SiC nanowires.Introduction Since the discovery of carbon nanotubes by Iijima[1], there has been great interest in the synthesis and characterization of other one-dimensional (1D) structures. Nanowires, nanorods and nanobelts constitute an important class of 1D nanostructures, which provide models to study the relationship between electrical transport, optical and other properties with dimensionality and size confinemen[2~7]. The 1D nanowires can also act as active components in devices as revealed by recent investigations[8,9]. Up to now, several techniques for preparing SiC nanowires have been developed. Dai et al.[5] synthesized SiC nanorods via the reaction of carbon nanotubes with SiO. Zhou et al. [6] synthesized SiC nanowires by hot filament chemical vapor deposition (CVD). Liang et al.[9] grew SiC nanowires by carbothermal reduction of silica xerogels embedded with Fe nanoparticles, etc. However, many of these routes involved complex processes and high cost. The usage of metal catalyst for the vapor–liquid–solid (VLS) growth mechanism makes it difficult to remove the resident catalyst after the synthetic process. In this paper, it is reported that a simple and low cost synthetic route is developed for the preparation of SiC nanowires by microwave heating technique without any catalyst. The prepared nanowires have core-shell structure with the diameters between 20 to 100nm. The growth of these SiC nanowires is considered to involve a VLS process.
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GULEN, Mahir, Hamza DUNYA, Recep TAS, and Vedat Emin AYAZ. "Design of MnS@MWCNT Nanocomposite Cathode for Ultra-high Efficient Supercapacitors." International Conference on Pioneer and Innovative Studies 1 (June 13, 2023): 395–98. http://dx.doi.org/10.59287/icpis.862.
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The aim of this study was to investigate the usability of MnS (Manganese Sulfide) nanoparticlesin supercapacitor applications. MnS nanoparticles were synthesized using the microwave synthesis method.Additionally, a multi-walled carbon nanotube (MWCNT) was incorporated into the MnS structure toprepare MnS@%10MWCNT. The microwave synthesis method was chosen due to its fast, energy-efficient,and easily controllable synthesis process. The size and morphological properties of the synthesizednanoparticles were determined using analytical techniques such as X-ray diffraction (XRD) and scanningelectron microscopy (SEM). The results demonstrated that the microwave-synthesized MnS nanoparticlespossessed a crystalline structure and a homogeneous distribution. The incorporation of MWCNT wasconfirmed through SEM images and XRD analysis. Subsequently, the usability of the synthesized MnS andMnS@%10MWCNT nanoparticles in supercapacitor applications was evaluated. The supercapacitorperformance was examined using electrochemical characterization methods such as cyclic voltammetry andcontinuous charge-discharge tests. The results of the study revealed that MnS nanoparticles exhibited highcapacitance and fast charge-discharge characteristics in supercapacitor devices. Furthermore, it wasobserved that the capacitance and stability increased with the incorporation of MWCNT. This studydemonstrates the potential of MnS and MnS@%10MWCNT nanoparticles in energy storage. Themicrowave-synthesized MnS and MnS@%10MWCNT nanoparticles highlight their potential insupercapacitor applications. These findings represent an important step towards the expansion ofnanomaterials' utilization in energy storage and the development of more efficient supercapacitor devices.
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Bogush, V. A., L. V. Lynkou, N. V. Nasonova, S. L. Prischepa, E. S. Belousova, O. V. Boiprav, H. V. Davydau, V. A. Papou, A. V. Patapovich, and H. A. Pukhir. "Research and Development in the Field of Creating Materials, Technologies and Safety Equipment." Doklady BGUIR 22, no. 2 (April 16, 2024): 42–54. http://dx.doi.org/10.35596/1729-7648-2024-22-2-42-54.
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Technologies for the manufacture of microwave electromagnetic shields based on powdered carbon, foil and composite multilayer materials are presented. Technological methods for their manufacture and shielding properties are described, and the main mechanisms leading to increased shielding properties are considered depending on the manufacturing technology, composition and alternation of composite layers. It is shown that the values of the reflection coefficient of electromagnetic radiation in the frequency range 2–17 GHz for the shields considered reach a value of (–20) dB. Microwave absorbers with a reflection characteristic lower than (–10.0) dB (down to (–52.0) dB) in the frequency band 8.0–12.0 GHz are developed, and the electrophysical parameters, composition and concentration of components of the composite materials for such microwave absorbers are determined. The systems for active protection of speech information that use combined masking signals consisting of “white” noise and speech-like signals as masking signals, along with “white” noise are considered. Criteria have been developed for the approach to selecting speakers and audiences when assessing speech intelligibility to solve problems of protecting speech information and methods for experimental studies of speech intelligibility against a background of masking acoustic noise. Technologies for the formation of nanocomposites based on carbon nanotubes and nanoparticles of ferromagnetic materials are presented to increase the degree of coherence of the spin texture at macroscopic distances, increase the degree of security of electronic products to strong magnetic fields and noise immunity. It has been shown that at certain concentrations of ferromagnetic nanoparticles, micromagnetic parameters increase, ensuring high performance of active elements in magnetic fields. The role of carbon in this case turns out to be decisive. The presented results seem promising for use in the creation of anechoic chambers, partitions for separating indoor zones intended for the location of electronic devices, products for protecting humans from the effects of electromagnetic radiation in the microwave range, and the formation of combined masking signals in the form of “white” noise for devices protection of speech information, composite coatings to level out the effects of a constant magnetic field on electronic products.
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Quinton, Betty T., Paul N. Barnes, Chakrapani V. Varanasi, Jack Burke, Bang-Hung Tsao, Kevin J. Yost, and Sharmila M. Mukhopadhyay. "A Comparative Study of Three Different Chemical Vapor Deposition Techniques of Carbon Nanotube Growth on Diamond Films." Journal of Nanomaterials 2013 (2013): 1–9. http://dx.doi.org/10.1155/2013/356259.
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This paper compares between the methods of growing carbon nanotubes (CNTs) on diamond substrates and evaluates the quality of the CNTs and the interfacial strength. One potential application for these materials is a heat sink/spreader for high-power electronic devices. The CNTs and diamond substrates have a significantly higher specific thermal conductivity than traditional heat sink/spreader materials making them good replacement candidates. Only limited research has been performed on these CNT/diamond structures and their suitability of different growth methods. This study investigates three potential chemical vapor deposition (CVD) techniques for growing CNTs on diamond: thermal CVD (T-CVD), microwave plasma-enhanced CVD (MPE-CVD), and floating catalyst thermal CVD (FCT-CVD). Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (TEM) were used to analyze the morphology and topology of the CNTs. Raman spectroscopy was used to assess the quality of the CNTs by determining theID/IGpeak intensity ratios. Additionally, the CNT/diamond samples were sonicated for qualitative comparisons of the durability of the CNT forests. T-CVD provided the largest diameter tubes, with catalysts residing mainly at the CNT/diamond interface. The MPE-CVD process yielded non uniform defective CNTs, and FCT-CVD resulted in the smallest diameter CNTs with catalyst particles imbedded throughout the length of the nanotubes.
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Ortega-Cervantez, G., R. Gómez-Aguilar, G. Rueda-Morales, and J. Ortiz-López. "Microwave-assisted synthesis of sponge-like carbon nanotube arrays and their application in organic transistor devices." Journal of Materials Science: Materials in Electronics 27, no. 12 (July 27, 2016): 12642–48. http://dx.doi.org/10.1007/s10854-016-5397-1.
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Nasikhudin, Nasikhudin, Yusril Al Fath, Istiqomah Istiqomah, Hari Rahmadani, Markus Diantoro, and Herlin Pujiarti. "Silver Nanowires (AgNWs) Post-Treatment Effect in Application of Flexible Transparent and Conductive Electrodes: A Mini Review." Materials Science Forum 1118 (March 22, 2024): 47–57. http://dx.doi.org/10.4028/p-e4avqd.
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Transparent flexible electrodes (TFEs) are extremely crucial for expanding flexible and wearable electronic devices. Silver nanowires (AgNWs) have been extensively investigated as an alternative to replace Indium Tin Oxide (ITO) as a commercial TFE due to their high conductivity, transparency, and flexibility. AgNWs have replaced ITO-based electrodes as the preferred approach in flexible, transparent, and conductive electrodes (FTCE). AgNWs outperform other materials, such as Reduced Graphene Oxide (RGO), ceramic material, Carbon Nanotubes (CNT), and conductive polymers, in terms of electrical conductivity, transmittance, flexibility, and low sheet resistance. Numerous techniques, including as electrospinning, spray coating, spin coating, and doctor blades, are used to use AgNWs as flexible substrates. Seed-based growth and template-assisted synthesis are two fundamental synthesis techniques that could be used to generate AgNWs. However, poor adhesiveness, and thermal and electrical stability, begin to be bottlenecks for AgNWs as high deployment in a variety of devices. So AgNWs synthesis process began to shift to other methods, such as wet chemical and polyol. In this paper, short and clear summary of various advances including post-treatment methods such as UV radiation, microwave, sonication, quenching, and so on is conducted to be one step forward to test mechanical properties and to improve AgNWs performance.
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Itas, Yahaya Saadu, Chifu E. Ndikilar, Tasiu Zangina, Hafeez Yusuf Hafeez, A. A. Safana, Mayeen Uddin Khandaker, Pervaiz Ahmad, et al. "Synthesis of Thermally Stable h-BN-CNT Hetero-Structures via Microwave Heating of Ethylene under Nickel, Iron, and Silver Catalysts." Crystals 11, no. 9 (September 9, 2021): 1097. http://dx.doi.org/10.3390/cryst11091097.
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Initially, three samples of carbon nanotubes (SWCNTs) were synthesized from neem tree material. Afterward, these samples were coated with hexagonal boron nitride (h-BN) to form h-BN and CNT composite (h-BN-CNT). The essence of using h-BN (being a perfect insulator) with armchair SWCNT (being a conductor) is to create an interface between an insulator and conductor. The samples were treated under three different transition metal nanoparticles; silver, iron, and nickel. Thermogravimetric (TGA) analysis reveals that h-BN/CNT is thermally more stable with silver than iron and nickel nanoparticles. TGA profile showed resistance to mass loss at the beginning due to the higher thermal resistivity by the impurity compounds. The DFT calculation, generalized gradient approximation (GGA), and Perdew–Burke–Ernzerhof (PBE) analysis found engineered bandgap energy of 3.4 eV for the synthesized h-BN-CNT heterostructure. Because of its unique structural and electronic properties such as tunable bandgaps, the h-BN-CNT heterostructure may open new ways for manipulating excitons in the CNTs, and thus can be explored to develop various new electronic devices.
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Alijani, Mahnaz, Ben D. Wiltshire, Mohammad H. Zarifi, and Jan M. Macak. "TiO2 Nanotube Integrated Microwave Resonator UV Sensor." ECS Meeting Abstracts MA2022-01, no. 52 (July 7, 2022): 2167. http://dx.doi.org/10.1149/ma2022-01522167mtgabs.
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Ultraviolet (UV) irradiation is extensively utilized in numerous applications such as outer space communication, biological disinfection, memory storage, optoelectronic circuits, and biological analysis [1]. Excessive exposure to UV irradiation is deleterious and causes adverse health effects, for instance, premature aging and skin cancer. A rapid and highly sensitive device for the detection of UV is in great demand in various applications. Recently, planar microwave resonator sensors have demonstrated attractive and robust performance providing high sensitivity, real-time response, and low-cost fabrication process [2]. The planar microwave resonators can easily be integrated with nanostructured materials to make them sensitive to UV radiation via absorption and subsequent charge generation [3]. Among various wide bandgap metal oxides such as TiO2, ZnO, SnO2, one-dimensional TiO2 nanotubes (TNTs) are favorable in UV photodetectors as they possess, except intrinsic TiO2 properties high active surface area and their unique hollow geometry enables increased charge trapping and, a direct pathway for rapid transport of photogenerated carriers [4-6]. Therefore, the use of high aspect ratio (HAR) TNTs might offers superior sensing performance in the UV region. In this presentation, the impact of TNT thicknesses on the UV sensitivity of the planar microwave resonator’s response will be investigated. We will demonstrate the use of a high frequency microwave resonator integrated with different thicknesses (50, 80, 100 µm) of TNT membranes. The presented work will aid in selecting an optimized thickness of TNT membranes with a large active surface-to-volume ratio to provide the highest sensitivity to UV irradiation. We expect this investigation to act as basis for expanding the use of HAR TNTs to effectively develop low-cost, easy to use and robust microwave UV sensors in a wide range of applications. Experimental details and recent results will be presented and discussed.
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Marzal, Vicente, Juan Carlos Torres, Braulio García, Isabel Pérez, José Manuel Sánchez, and Wiktor Piecek. "Study of electrical behavior of liquid crystal devices doped with titanium dioxide nanoparticles." Photonics Letters of Poland 9, no. 1 (March 31, 2017): 20. http://dx.doi.org/10.4302/plp.v9i1.712.
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In the last years, nanostructures are widely used as dopants in liquid crystals to manipulate either their electrical or optical properties. In this work, we have analyzed the electrical response of a planar cell filled with a mixture of E7 liquid crystal doped with TiO2 nanoparticles. The effect of these dopants on the effective permittivity and conductivity of the cell has been studied in a wide frequency range at different temperatures. Full Text: PDF ReferencesP.J. Pinzón, I. Pérez, C. Vázquez and J.M.S. Pena, "Reconfigurable ????×????1×2 wavelength selective switch using high birefringence nematic liquid crystals", App.Opt. 51, pp.5960-5965 (2012) CrossRef C. Carrasco-Vela, X. Quintana, E.Otón, M.A. Geday, J.M. Otón, "Security devices based on liquid crystals doped with a colour dye", Opto?Electron. 19, pp.496-500 (2011). CrossRef J. Torrecilla, E. Ávila-Navarro, C. Marcos, V. Urruchi, J.M.S. Pena, J. Arias, M.M Sánchez-López, "Microwave Tunable Notch Filter Based on Liquid Crystal Using Spiral Spurline Technology", Microw. Opt. Technol. Lett. 55, 2420-2423 (2013). CrossRef G.B. Hadjichristov, Y. G. Marinov, A. G. Petrov, E. Bruno, L.Marino, N. Scaramuzzab, "Electro-Optics of Nematic/Gold Nanoparticles Composites: The Effect from Dopants", Mol. Cryst. Liq. Cryst. 610, 135?148 (2015). CrossRef T. Miyama, J. Thisayukta, H. Shiraki, Y. Sakai, Y. Shiraishi, N. Toshima, S. Kobayashi, "Fast Switching of Frequency Modulation Twisted Nematic Liquid Crystal Display Fabricated by Doping Nanoparticles and Its Mechanism", Jpn. J. Appl. Phys. 43, 2580 -2584 (2004). CrossRef W. T. Chen, P. S. Chen, C. Y. Chao, "Effect of Doped Insulating Nanoparticles on the Electro-Optical Characteristics of Nematic Liquid Crystals", Jpn. J. Appl. Phys. 48, 015006 (2009) CrossRef A. Siarkowska, M. Chychłowski, T.R. Woliński and A.Dybko. "Titanium nanoparticles doping of 5CB infiltrated microstructured optical fibers", Phot. Lett. Poland 8, 29-31 (2016). CrossRef O. Buchnev, A. Dyadyusha,M. Kaczmarek, V.Reshetnyak, Y. Reznikov, "Enhanced two-beam coupling in colloids of ferroelectric nanoparticles in liquid crystals", J. Opt. Soc. Am. 24, 1512-1516 (2004). CrossRef A. García-García, R. Vergaz, J.A. Algorri, X. Quintana, J.M. Otón, Beilstein J. "Electrical response of liquid crystal cells doped with multi-walled carbon nanotubes", Nanotechnol. 6, 396?403 (2015). CrossRef R. Pratibha, K. Park, I.I. Smalyukh and W. Park, "Tunable optical metamaterial based on liquid crystal-gold nanosphere composite", Opt. Express 17,19459-19469 (2009). CrossRef J.C. Torres, B. Garcia-Camara, I. Perez, V. Urruchi, J.M. Sanchez-Pena, "Temperature-Phase Converter Based on a LC Cell as a Variable Capacitance", Sensors 15, 5594 ? 5608 (2015). CrossRef P. Kumar, A. Kishore and A, Sinha, "Effect of different concentrations of dopant titanium dioxide nanoparticles on electro-optic and dielectric properties of ferroelectric liquid crystal mixture ", Adv. Mater. Lett. 7, 104-110 (2016). CrossRef R.K. Shukla, C.M. Liebig, D.R. Evans, and W. Haase, "Electro-optical behaviour and dielectric dynamics of harvested ferroelectric LiNbO3 nanoparticle-doped ferroelectric liquid crystal nanocolloids", RSC Adv. 4, 18529-18536 (2014). CrossRef
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Kondo, Hiroki, Han Zhou, Takayoshi Tsutsumi, Kenji Ishikawa, Makoto Sekine, and Masaru Hori. "(Invited) Recent Progress in the Synthesis of Functional and Three-Dimensional Carbon Nano-Composites By Gas-Liquid Interface Plasma." ECS Meeting Abstracts MA2023-01, no. 20 (August 28, 2023): 1498. http://dx.doi.org/10.1149/ma2023-01201498mtgabs.
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Carbon nanomaterials, such as fullerene, carbon nanotubes (CNT), graphene sheets, and so forth, play indispensable roles in nanotechnology research and applications. Due to their unique self-organized nanostructures and properties, various types of applications using them are expected and have been developed. Furthermore, in recent years, heteroatom-doped carbon nano-composite materials that exhibit catalytic activity are attracting much attention as non-platinum catalysts. Especially, nitrogen (N)-doped nanographene materials are well-known to have high catalytic activity. Pyridinic-N is known as a key component to express catalytic activity [1]. There are two ways to obtain nitrogen-doped carbon nanomaterials. One is the addition of N into carbon nanomaterials during their synthesis, and the other is the post-nitridation after the synthesis, which often used nitrogen plasma. Especially in the latter case, the synthesis method of nanographene itself can be divided into two types of methods. One is the direct synthesis of the powder, and the other is the exfoliating from graphene oxide (GO) or bulk graphite in physical or chemical ways. Hydrothermal treatment using microwaves is one of the effective methods for simultaneous exfoliation, three-dimensional nanopore structuring, and nitrogen addition. While electronic device applications generally need high-quality graphene sheets synthesized by epitaxial growth, or chemical vapor deposition (CVD) methods at high temperatures up to 1,000°C, some kinds of applications, such as sensors, batteries, additives to polymers, and so forth, need a large amount of nanographene power. For that purpose, a reduction of GO is well known, but the quality of the synthesized graphene is not high enough. Recently, we have established a high-speed synthesis method of nanographene materials with high crystallinity by a plasma discharge at gas-liquid interfaces with alcohol sources. By this method, a synthesis rate of nanographene over 1 mg/min and higher crystallinity of nanographene than the reduced GO have been realized. On the other hand, there is a trade-off relationship between the synthesis rate and crystallinity, when different types of alcohols were used as a feedstock gas. When ethanol,1-propanol, and 1-butanol were used, it was found that the higher synthesis rates were obtained by the higher-molecular weight alcohols, while its crystallinity was lower. In the comparison between hexane (C6H14) and hexanol (C6H13OH), in the case of hexane, the synthesis rate is about twice as high as that in the case of hexanol, but the crystallinity is lowered. These results indicate that this trade-off relationship is attributed to a ratio of carbon (C) and oxygen (O) atoms. O-related radicals (O, OH, etc.) in plasma could have etching effects of amorphous or low-crystallinity carbon components. Actually, according to the results of plasma diagnostic measurements and residual liquid analyses, it was found that crystallinity of nanographene materials degraded with decrease in OH intensity in plasma. Furthermore, small radicals such as C2 and CHx contribute to the synthesis of nanographene rather than by-products with a six-membered ring structure. Furthermore, we have also found functionalization and structural control of nanographene materials by additive agents to alcohol sources at in-liquid plasma processes. Using an iron phthalocyanine with ethanol, size of carbon nanosheets increased up to micrometer. And they showed excellent catalytic characteristics thorough 4-electron reduction pathway. According to the verification results of dependence on synthesis conditions such as the type of additive, such the catalytic activity is induced by pyridinic C-N bonds. In the case of this way, to increase pyridinic C-N bonds and improve catalytic performance, iron phthalocyanine is much better than Hemin, even which also included Fe and N. These knowledges obtained in this study will open the way to the next-generation green energy solutions, such as high-performance catalytic electrode for the fuel cell. [1] D. Guo, R. Shibuya, C. Akiba, S. Saji, T. Kondo, and J. Nakamura. Science 351 (2016) 361–365. [2] J. Wang, W. Wu, H. Kondo, T. Fan, H. Zhou, Nanotechnology, NANO-132006.R1 (2022), online. [3] T. Hagino, H. Kondo, K. Ishikawa, H. Kano, M. Sekine, M. Hori, Appl. Phys. Express 5 (2012) 035101. [4] T. Amano, H. Kondo, K. Ishikawa, T. Tsutsumi, K. Takeda, M. Hiramatsu, M. Sekine, M. Hori, Appl. Phys. Express 11 (2017) 015102. [5] H. Kondo, R. Hamaji, T. Amano, K. Ishikawa, M. Sekine, M. Hiramatsu, M. Hori, Plasma Process. Polym. 19, (2022) 2100203.
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Sohn, Jung Inn, Seonghoon Lee, Yoon-Ho Song, Sung-Yool Choi, Kyoung-Ik Cho, Kee-Soo Nam, and Young-Il Kang. "Large Field Emission from Vertically Well-aligned Carbon Nanotubes." MRS Proceedings 633 (2000). http://dx.doi.org/10.1557/proc-633-a14.9.
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AbstractWe have grown well-aligned carbon nanotube arrays by thermal chemical vapor deposition at 800°C on Fe nanoparticles deposited by a pulsed laser on a porous Si substrate. Porous Si substrates were prepared by the electrochemical etching of p-Si(100) wafers with resistivities of 3 to 6 ωcm. These well-aligned carbon nanotube field emitter arrays are suitable for electron emission applications such as cold-cathode flat panel displays and vacuum microelectronic devices like microwave power amplifier tubes. Field emission characterization has been performed on the CNT-cathode diode device at room temperature and in a vacuum chamber below 10−6 Torr. The anode is maintained at a distance of 60[.proportional]m away from the carbon nanotube cathode arrays through an insulating spacer of polyvinyl film. The measured field emitting area is 4.0×10−5cm2. Our carbon nanotube field emitter arrays emit 1mA/cm2at the electric field, 2V/[.proportional]m. And they emit a large current density as high as 80mA/cm2 at 3V/[.proportional]m. The open tip structure of our carbon nanotubes and their good adhesion through Fe nanoparticles to the Si substrate are part of the reason why we can attain a large field emission current density within a low field. The field emitter arrays in our diode device are vertically well-aligned carbon nanotubes on the Si-wafer substrate.
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Singh, Navdeep, and Gagan Deep Aul. "Carbon Nanotubes based composites for electromagnetic absorption- A review." Current Applied Materials 01 (August 3, 2021). http://dx.doi.org/10.2174/2666731201666210803110914.
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: Radar is a delicate detection device and since its evolution different techniques for reducing electromagnetic reflections have been discovered. This paper provide concise review on fundamentals of absorption which reduces radar cross section from stealth target with which radar cross section has effects to survivability and mission capability. The reduction of radar cross section depend on dielectric and magnetic properties of material. The first section reviews the Radar Absorbing Material (RAM) in order to provide a background on fundamentals, various stealth techniques for absorption and its properties at microwave frequencies. The second section reviews the Multi-Walled Carbon Nanotubes and its different composites by encapsulation of other metals, polymers or epoxies into it and its microwave absorption properties were studies at microwave frequencies. Multi-Walled Carbon Nanotubes based composites for microwave absorption are reviewed on the basis of various factors; material composition, reflection loss performance, thickness, complex permittivity, complex permeability, dielectric tangent loss, magnetic tangent loss, bandwidth, and frequency band.
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Meng, Xiangwei, Jing Qiao, Jiurong Liu, Lili Wu, Zhou Wang, and Fenglong Wang. "Bioinspired Hollow/Hollow Architecture with Flourishing Dielectric Properties for Efficient Electromagnetic Energy Reclamation Device." Small, October 27, 2023. http://dx.doi.org/10.1002/smll.202307647.
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AbstractThe exploitation of advanced electromagnetic functional devices is perceived as the effective prescription to deal with environmental contamination and energy deficiency. From the perspective of observing and imitating nature, pine branch‐like zirconium dioxide/cobalt nanotubes@nitrogen‐doped carbon nanotubes are synthesized victoriously through maneuverable electrospinning process and follow‐up thermal treatments. In particular, introducing carbon nanotubes on the surface of hollow nanofibers to construct hierarchical architecture vastly promoted the material's dielectric properties by significantly augmenting specific surface area, generating abundant heterogeneous interfaces, and inducing the formation of defects. Supplemented by the synergistic effect between each constituent, ultra‐strong attenuation capacity and perfect impedance matching characteristics are implemented simultaneously, and jointly made contributions to the splendid microwave absorption performance with a minimum reflection loss of −67.9 dB at 1.5 mm. Moreover, this fibrous absorber also exhibited promising potential to be utilized as a green and efficient electromagnetic interference shielding material when the filler loading is enhanced. Therefore, this design philosophy is destined to inspire the future development of energy conversion and storage devices, and provide theoretical direction for the creation of sophisticated electromagnetic functional materials.
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Gupta, Sanju, Rishi J. Patel, and Nathaniel D. Smith. "Advanced Carbon-based Material as Space Radiation Shields." MRS Proceedings 851 (2004). http://dx.doi.org/10.1557/proc-851-nn6.3.
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ABSTRACTCarbon-based materials including microcrystalline diamond, nanocrystalline diamond, and carbon nanotubes films were prepared by microwave plasma-assisted chemical vapor deposition (MWCVD) technique. While the former were submitted to gamma radiation doses of 1, 5, and 20 Mrad, the latter to low energy electron beam of 30 keV or to 30 GeV/cm2) to study the radiation-induced structural transformation. The characterizations were performed prior to and after irradiation using Raman spectroscopy, scanning electron microscopy, and X-ray diffraction, techniques. Microcrystalline diamond showed a dramatic modification in the structural properties only after a cumulative dose of 26 Mrad (2 Grad/cm2), while nanocrystalline carbon showed a relatively small but systematic transformation with increasing gamma radiation dose. The results indicate that nanocrystalline carbon tends to reach a state of saturation when submitted to 26 Mrad doses of gamma radiation, suggesting the possibility of fabricating radiation buffer materials that would undergo internal sp3 ⇔ sp2 inter-conversion while absorbing ionizing radiation without changing their average microstructure and protecting the device/material underneath. Single- and multi-walled nanotubes exhibited structural modifications after 5.5–8 hrs of continuous exposure to electron beam. The variation in the characteristic X-ray peaks for multi-walled and single-walled corresponding to intertube spacing and the high frequency Raman band around 1580 cm−1 (G band) are reflected in their corresponding spectra. The results indicate that there is an increase in the intertube spacing for multi-walled nanotubes due to electron irradiation. While single-wall nanotubes tends to ‘collapse’ after > 8 hours of exposure forming multi-wall nanotubes analyzed using scanning electron microscopy and Raman spectroscopy. These C materials can be employed for preventing space radiation from reaching sensitive materials and electronic devices at least for short term experiments and entitled them as ‘space radiation shields’.
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Bower, C., O. Zhou, W. Zhu, A. G. Ramirez, G. P. Kochanski, and S. Jin. "Fabrication and Field Emission Properties of Carbon Nanotube Cathodes." MRS Proceedings 593 (1999). http://dx.doi.org/10.1557/proc-593-215.
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ABSTRACTA variety of carbon nanotube films have been fabricated and tested as cold cathodes. A spray deposition technique was developed for processing as-grown bulk nanotubes, both single-walled and multi-walled, into films of randomly oriented nanotubes. Films of randomly oriented multi-walled nanotubes were grown using thermal chemical vapor deposition, and arrays of well-aligned multi-walled nanotubes have been fabricated using a microwave plasma enhanced chemical vapor deposition technique. The emission current-voltage (I-V) characteristics of these nanotube cathodes have been measured. Both multi-walled (random and aligned) and single-walled carbon nanotubes exhibit low turn-on fields (∼ 2 V/μm to generate 1 nA) and threshold fields (< 5 V/μm to generate 10 mA/cm2). Significantly, these cathodes were capable of operation at very large current densities (> 1A/cm2), making them candidates for application in a variety of vacuum microelectronic devices.
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Gupta, Sanju. "Carbon Nanotubes as Potential Cold Cathodes for Vacuum Microelectronic Applications." MRS Proceedings 963 (2006). http://dx.doi.org/10.1557/proc-0963-q14-02.
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ABSTRACTMaterials science is playing a dramatic role in discovering new materials with tailored physical properties. Cold cathodes/field emitters are one of the examples. Electron field emitting materials are of vital importance for a variety of vacuum microelectronic devices including field emission displays for flat panel displays, electron microscopes, X-ray generators, and vacuum lamps. This is the driving force to investigate the advanced nanostructured carbons as cold cathodes as one of the potential candidates. Recently, they are also being proposed for thermionic power generators. The rationale is that reducing one or more dimensions of a system below some critical length changes the systems' physical properties, where carbon nanotubes (CNTs) in the class of carbon nanostructures serve as a model example. In this paper, synthesis and characterization of vertically aligned multiwall and single-/double-wall carbon nanotube films using a microwave plasma-assisted chemical vapor deposition technique for vacuum microelectronics is presented. Recent advances in their synthesis, processing, and characterization indicate that the above mentioned potential is slowly being realized. Experiments showed that by continuous reduction in the thickness of the catalyst film produces hollow concentric tubes in contrast to bamboo-like multiwalled tubes with larger thickness. To assess the electron field emission properties, besides the traditional field emission (I-V) properties, temperature dependent field electron emission microscopy (T-FEEM) enabling real-time imaging of electron emission providing information on emission site density, temporal variation of the emission intensity, and insight into the role of adsorbates from nanotube films will be discussed. Physics based models (such as negative or low electron affinity, geometric enhancement, surface dipole, tunneling due to adsorbates, structure modification due to doping etc.) will be described to support the experimental observations in addition to weak thermionic field emission contribution. These findings provided a great insight into the field emission mechanism and a contrasting comparison between small and large diameter carbon nanotubes.
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Cott, Daire, Masahito Sugiura, Nicolo Chiodarelli, Kai Arstila, Philipe M. Vereecken, Bart Vereecke, Sven Van Elshocht, and Stefan De Gendt. "A CMOS Compatible Carbon Nanotube Growth Approach." MRS Proceedings 1284 (2011). http://dx.doi.org/10.1557/opl.2011.645.
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ABSTRACTIn future technology nodes, 22nm and below, carbon nanotubes (CNTs) may provide a viable alternative to Cu as an interconnect material. CNTs exhibit a current carrying capacity (up to 109 A/cm2), whilst also providing a significantly higher thermal conductivity (SWCNT ~ 5000 WmK) over Copper (106 A/cm2 and ~400WmK). However, exploiting such properties of CNTs in small vias is a challenging endeavor. In reality, to outperform Cu in terms of a reduction in via resistance alone, densities in the order of 1013 CNTs/cm2 are required. At present, conventional thermal CVD of carbon nanotubes is carried out at temperatures far in excess of CMOS temperature limits (400 C). Furthermore, high density CNT bundles are most commonly grown on insulating supports such as Al2O3 and SiO2 as they can effectively stabilize metallic nanoparticles at elevated temperatures but this limits their application in electronic devices. To circumvent these obstacles we employ a remote microwave plasma to grow high density CNTs at a temperature of 400 C on conductive underlayers such as TiN. We identify some critical factors important for high-quality CNTs at low temperatures such as control over the catalyst to underlayer interaction and plasma growth environment while presenting a fully CMOS compatible carbon nanotube synthesis approach
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Liao, Qingliang, Yue Zhang, Liansheng Xia, Junjie Qi, Yunhua Huang, Zi Qin, Ya Yang, and Zhanjun Gao. "Field Emission Properties of Large Area Carbon Nanotube Cathodes in DC and Pulse Modes." MRS Proceedings 1081 (2008). http://dx.doi.org/10.1557/proc-1081-p15-07.
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AbstractA large area carbon nanotube cathode was fabricated by use of a screen printing method. The emission properties of the cathode were investigated in both direct current and pulse mode experiments. In the direct current mode, the cathode has high field enhancement factor and high emission current density. In the double-pulse mode, the emission current density can approach 267 A/cm2 at an applied electric field of 15.4 V/um. Steady intense electron beams were obtained from the cathode. The results proved that the emission mechanism of CNTs at pulse electric field is plasma-induced field emission. The carbon nanotube cathode is suitable for not only field emission display applications but also high-power microwave device applications.
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Alston, Jeffrey R., Dylan Brokaw, Colton Overson, Thomas A. Schmedake, and Jordan C. Poler. "Hybrid SWCNT - NiO Composites for Supercapacitor Applications." MRS Proceedings 1552 (2013). http://dx.doi.org/10.1557/opl.2013.624.
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ABSTRACTSupercapacitor devices promise to be an effective means of storing energy, and delivering power for personal electronics, remote sensors, and transportation.1, 2 Rare earth metals, such as ruthenium, have been used and report high value of capacitance, specific power, and energy.4 Nevertheless, the rarity of such metals prevent their practical use. In this study we utilize an earth-abundant nickel and a controlled microwave synthesis to create nickel oxide (NiO) with an optimal nanostructure for capacitance. To surpass the lofty series resistance associated with metal oxides such as NiO, we exploit the conductive properties of single and multi-walled carbon nanotubes. The carbon nanotubes and NiO can benefit from the presence of each other by preventing unnecessary aggregation.
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Xu, Lele, Chenhui Sun, Liang Chen, Jingsong Yang, Xinxin Yuan, and Minghai Chen. "High rate carbon nanotube/magnetic-sheet composites in-situ synthesized by fluidized bed for high-frequency microwave absorption." New Journal of Chemistry, 2023. http://dx.doi.org/10.1039/d3nj04378a.
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At present, the large-scale preparation of carbon nanotubes (CNTs) can be achieved by using fluidized bed devices and chemical vapor deposition (CVD) process. We selected layered double hydroxide (LDH) as...
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Cola, Baratunde A., Placidus B. Amama, Xianfan Xu, and Timothy S. Fisher. "Effects of Growth Temperature on Carbon Nanotube Array Thermal Interfaces." Journal of Heat Transfer 130, no. 11 (September 2, 2008). http://dx.doi.org/10.1115/1.2969758.
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Due to their excellent compliance and high thermal conductivity, dry carbon nanotube (CNT) array interfaces are promising candidates to address the thermal management needs of power dense microelectronic components and devices. However, typical CNT growth temperatures (∼800°C) limit the substrates available for direct CNT synthesis. A microwave plasma chemical vapor deposition and a shielded growth technique were used to synthesize CNT arrays at various temperatures on silicon wafers. Measured growth surface temperatures ranged from 500°Cto800°C. The room-temperature thermal resistances of interfaces created by placing the CNT covered wafers in contact with silver foil (silicon-CNT-silver) were measured using a photoacoustic technique to range from approximately 7mm2°C∕Wto19mm2°C∕W at moderate pressures. Thermal resistances increased as CNT array growth temperature decreased primarily due to a reduction in the average diameter of CNTs in the arrays.
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Ebrahimzadeh, Majid, Abdolrasoul Gharaati, Alireza Jangjoo, and Hamed Rezazadeh. "Investigation of Electromagnetic Wave Absorption Properties of Ni-Co and MWCNT Nanocomposites." Recent Patents on Nanotechnology 17 (November 18, 2022). http://dx.doi.org/10.2174/1872210517666221118110054.
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BACKGROUND: In recent years, severe electromagnetic interference among electronic devices has been caused by the unprecedented growth of communication systems. Therefore, microwave absorbing materials are required to relieve these problems by absorbing the unwanted microwave. In the design of microwave absorbers, magnetic nanomaterials have to be used as fine particles dispersed in an insulating matrix. Besides the intrinsic properties of these materials, the structure and morphology are also crucial to the microwave absorption performance of the composite. In this study, Ni-Co-MWCNT composites were synthesized, and the changes in electric permittivity, magnetic permeability, and reflectance loss of the samples were evaluated at frequencies of 2 to 18 GHz. METHODS: Nickel-Cobalt-Multi Wall Carbon Nanotubes (MWCNT) composites were successfully synthesized by the co-precipitation chemical method. The structural, morphological, and magnetic properties of the samples were characterized and investigated by X-ray diffractometer (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Vibrating Sample Magnetometer (VSM), and Vector Network Analyzer (VNA). RESULTS: The results revealed that the Ni-Co-MWCNT composite has the highest electromagnetic wave absorption rate with a reflectance loss of -70.22 dB at a frequency of 10.12 GHz with a thickness of 1.8 mm. The adequate absorption bandwidth (RL <-10 dB) was 6.9 GHz at the high-frequency region, exhibiting excellent microwave absorbing properties as a good microwave absorber. CONCLUSION: Based on this study, it can be argued that the Ni-Co-MWCNT composite can be a good candidate for making light absorbers of radar waves at frequencies 2- 18 GHz.
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Mahesh Kumar, J. "A Review on Semiconductor Fabrication to FPGA." International Journal of Advanced Research in Science and Technology, 2016, 610–16. http://dx.doi.org/10.62226/ijarst20160276.
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Researchers are experimenting with carbon nanotubes to Phenomenally change the way semiconductor devices are made. At the same time, there are innovations to address immediate needs such as improving yield, decreasing time – to – market, reducing leakage power, thermal management in multi – die stacks, new layout requirement and so on. The „Chips‟ are everywhere today, right from mobile phones and computer to microwave ovens and washing machines, and even in children‟s toys. There are millions of chips in the world and more are being produced every day, but did you know that these are still produced by a countable number of manufacturers across manufacturing plant, is a technology and resource – intensive factory that could cost anywhere between 1 billion and 10 billion dollars, or even more to set up
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Mohd Idris, Fadzidah, and Khamirul Amin Matori. "Enhancing Microwave Absorbing Properties of Nickel-Zinc-Ferrite with Multi-walled Carbon Nanotubes (MWCNT) Loading at Higher Gigahertz Frequency." Malaysian Journal of Science, Health & Technology, March 30, 2021, 1–7. http://dx.doi.org/10.33102/mjosht.v7i1.151.
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The rapid growth of electronic systems and devices operating within the gigahertz (GHz) frequency range has increased electromagnetic interference. In order to eliminate or reduce the spurious electromagnetic radiation levels more closely in different applications, there is strong research interest in electromagnetic absorber technology. Moreover, there is still a lack of ability to absorb electromagnetic radiation in a broad frequency range using thin thickness. Thus, this study examined the effect of incorporating magnetic and dielectric materials into the polymer matrix for the processing of radar absorbing materials. The experiment evaluated the sample preparation with different weight percentages of multi-walled carbon nanotubes (MWCNT) mixed with Ni0.5Zn0.5Fe2O4 (Nickel-Zinc-Ferrite) loaded into epoxy (P) as a matrix. The prepared samples were analysed by examining the reflectivity measurements in the 8 – 18 GHz frequency range and conducting a morphological study using scanning electron microscopy analyses. The correlation of the results showed that different amounts of MWCNT influenced the performance of the microwave absorber. As the amount of MWCNTs increased, the reflection loss (RL) peak shifted towards a lower frequency range and the trend was similar for all thicknesses. The highest RL was achieved when the content of MWCNTs was 2 wt% with a thickness of 2 mm with an RL of – 14 dB at 16 GHz. The 2.5 GHz bandwidth corresponded to the RL below -10 dB (90% absorption) in the range of 14.5 – 17 GHz. This study showed that the proposed experimental route provided flexible absorbers with suitable absorption values by mixing only 2 wt% of MWCNTs.
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Choi, Haeyoung, and Jong Uk Kim. "Improvement of Emission Current by Using CNT Based X-ray Tube." MRS Proceedings 963 (2006). http://dx.doi.org/10.1557/proc-0963-q10-50.
Full textAbstract:
ABSTRACTStudies on the electronic structure of carbon nanotube (CNT) are of much importance because of its efficient utilization in electronic vacuum devices [1]. These CNTs have many applications such as field emission display (FED), LCD backlight units, microwave amplifiers, lighting lamps, x-ray sources and so on. One of these applications is the electron emitter for x-ray source. In order to obtain x-ray images of relatively hard instruments or components such as PCB board or machine tools, high quantity of x-ray current is generally required. In this study, we report that the current density of x-ray source can be greatly enhanced by using the CNT emitter as a cathode. In general, the emission current of CNT emitter is very sensitive to gap distance between CNT emitter and grid metal mesh. In addition, the emission current is appeared to be different with respect to the kinds of metal meshes and their sizes employed in the measurement. Extensive results of these were reported in our recent works [2]. For example, as the distance between CNT emitter and grid metal mesh was getting shorter, the current density of the triode was getting larger. Detailed parameters and corresponding results were presented and some preliminary x-ray images were obtained and discussed in this study.
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Vaseashta, Ashok. "Geospatial Remote Sensing Using Advanced Sensor Systems." MRS Proceedings 1076 (2008). http://dx.doi.org/10.1557/proc-1076-k04-03.
Full textAbstract:
ABSTRACTRecently, various nanoscale materials, devices, and systems with remarkable properties have been developed, with numerous unique applications in chem.-bio sensors, nanophotonics, and nanobiotechnology. This presentation covers satellite and aerial remote sensing science and methodologies employing nanotechnology based advanced sensor systems to improve performance, resolutions, and security. Increased demand on monitoring, surveillance due to global war on terrorism, weather prediction, and environmental pollution detection and monitoring have necessitated geospatial sensing with high accuracy, speed, and authenticity. Plasmonic interactions on the nanoscale and nanophotonics have produced new phenomena and technologies surpassing the realms of possibilities with conventional photonics and electronics. These new technologies could include high spatial resolution near-field imaging, high efficiency information processing and transferring, high capacity optical data storage, flexible- and high contrast displays, and precise detection, control and manipulation of nanoscale devices and integrated systems. Elements utilizing refractive or diffractive surfaces have found applications in novel sub-wavelength nanostructures satellites. The nanophotonics structures coupled with lightweight structures and advanced nanotechnology based sensors have resulted in launching of nano-satellites by several countries. The use of nanophotonics in space through the combination of micro, nano, integrated and fibre-optic technologies is to reduce susceptibility of the system to EMI, reduction in the weight of the signal cables (< 1/20 of electrical), higher information transmission capacity (GHz), reduced weight and volume, opto-isolation of critical spacecraft subsystems, high speed optical processing of RF and microwave signals, low propagation loss, and enhanced security encryption capabilities. Carbon Nanotubes (CNTs) based field emission electron gun (FEG) employ low voltage for emission and are actively researched as cold cathode microwave generation devices. CNTs based composites provide light-weight and compact platform with mechanical and thermal robustness. Such satellite system can be placed in low Earth orbit (LEO) to medium Earth orbit (MEO) as multi-sensor satellite imagers with panchromatic, multi-spectral, area and hyper spectral sensors on a single focal plane array (FPA), to achieve medium to high resolution (2.5m to 15m) spatial sampling, wide swaths (up to 45km) and noise equivalent reflectance (NER) values of less than 0.5%. An evaluation of security risks, vulnerability, and strategies is presented for communications technologies used in gathering, processing, storing, and disseminating global environmental micro and nano sensors and satellite data.