Nano-derived sensors for high-temperature sensing of H2, SO2 and H2S

The emission of sulfur compounds from coal-fired power plants remains a significant concern for air quality. This environmental challenge must be overcome by controlling the emission of sulfur dioxide (SO2) and hydrogen sulfide (H2S) throughout the entire coal combustion process. One of the processes which could specifically benefit from robust, low cost, and high temperature compatible gas sensors is the coal gasification process which converts coal and/or biomass into syngas. Hydrogen (H2), carbon monoxide (CO) and sulfur compounds make up 33%, 43% and 2% of syngas, respectively. Therefore, development of a high temperature (\u3e500°C) chemical sensor for in-situ monitoring H2, H2S and SO2 levels during coal gasification is strongly desired. The selective detection of SO2/H2S in the presence of H2, is a formidable task for a sensor designer. In order to ensure effective operation of these chemical sensors, they must inexpensively function within the gasifier\u27s harsh temperature and chemical environment. Currently available sensing approaches, which are based on gas chromatography, electrochemistry, and IR-spectroscopy, do not satisfy the required cost and performance targets.;There is also a substantial necessity for microsensors that can be applied inexpensively, have quick response time and low power consumption for sustained operation at high temperature. In order to develop a high temperature compatible microsensor, this work will discourse issues related to sensor stability, selectivity, and miniaturization. It has been shown that the integration of nanomaterials as the sensing material within resistive-type chemical sensor platforms increase sensitivity. Unfortunately, nanomaterials are not stable at high temperatures due to sintering and coarsening processes that are driven by their high surface to volume ratio. Therefore, new hydrogen and sulfur selective nanomaterial systems with potentially highly selective and stable properties in the proposed harsh environment were investigated. Different tungstates and molybdates (WO3, MoO3, MgMoO4, NiMoO4, NiWO4, Sr2MgWO6 (SMW), Sr2MgMoO6 (SMM), SrMoO4, and SrWO4) were investigated at the micro- and nano-scale, due to their well-known properties as the reversible absorbents of sulfur compounds. Different morphologies of aforementioned compounds as well as microstructural alterations were also the subject of the investigation. The fabrication of the microsensors consisted of the deposition of the selective nanomaterial systems over metal based interconnects on an inert substrate. This work utilized the chemi-resistive (resistive-type) microsensor architecture where the chemically and structurally stable, high temperature compatible electrodes were sputtered onto a ceramic substrate. The nanomaterial sensing systems were deposited over the electrodes using a lost mold method patterned by conventional optical lithography.;Development of metal based high temperature compatible electrodes was crucial to the development of the high temperature sensor due to the instability of typically used noble metal (platinum) based electrode material over ceramic substrates. Therefore, the thermal stability limitations of platinum films with various adhesion layers (titanium (Ti), tantalum (Ta), zirconium (Zr), and hafnium (Hf)) were characterized at 800 and 1200°C. Platinum (Pt)-zirconium (Zr)-hafnium (Hf) were investigated. The high-temperature stable composite thin film architecture was developed by sequential sputter deposition of Hf, Zr and Pt. In addition to this multilayer architecture, further investigation was carried out by using an alternative DC sputtering deposition process, which led to the fabrication of a functionally-gradient platinum and zirconium composite microstructure with very promising high temperature properties. The final process investigated reduced labor, time and material consumption compared to methods for forming multilayer architectures previously discussed in literature.;In addition to electrical resistivity characterization of the different thin film electrode architectures, the chemical composition, and nano- and micro-structure of the developed nanomaterial films, as well as sensing mechanism, were characterized by means of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray and ultraviolet photoelectron spectroscopies (XPS and UPS), atomic absorption spectroscopy (AAS), X-ray diffraction (XRD), Raman spectroscopy, temperature programmed reduction (TPR) and transmission electron microscopy (TEM). The macro-configurations of the sensors were tested and analyzed for sensitivity and cross-sensitivity, response time and recovery time, as well as long term stability. The microsensor configuration with optimized nanomaterial system was tested and compared to a millimeter-size sensor platform in terms of sensitivity and accuracy. Electrochemical relaxation (ECR) technique was also utilized to quantify the surface diffusion kinetics of SO2 over the chosen sensor material surface. The outcomes of this research will contribute to the economical application of sensor arrays for simultaneous sensing of H2, H2S, and SO2

Quantum Transport Characterizations in Selective-Area Grown InGaAs Nanowire Networks

Selective-area-grown (also referred to as ‘templated’) semiconductor nanostructures have gen- erated considerable research interest in recent years as potential vehicles for the investigation of fundamental quantum phenomena as well as towards scalable networks for deployment in future quantum computers. Such structures made from III-V semiconductors, which can play host to effects such as strong spin-orbit interaction and Fermi-level pinning of the conduction band at the interface, are of interest due to the fast spin precession as well as being potential vehicles for realization of non-trivial topological states of matter. This nascent technology has relied on the bridging of growth techniques, nano-fabrication, low-temperature electronic transport studies, and compositional analysis during its development. The required expertise involved has resulted in fruitful collaborations between a number of re- search groups in different institutions, which has enabled steady progress. Devices have been fabricated on quasi-1D nanostructures comprised of InGaAs nanowires grown atop defect-free GaAs nanomembranes, first with bulk-doping of Si + donors in the InGaAs wires in order to demonstrate a proof-of-principle for the system. Later, devices utilizing modulation doping strategies in order to reduce impurity scattering - while still providing the necessary additional carriers for transport - have been realized, measured, and analysed. Devices with branched geometries have been produced and quantum intereference effects have been observed across the junctions. Important transport parameters such as mean free paths, coherence lengths and spin-orbit lengths have been extracted in order to characterize the structures and motivate the next steps along the evolution of the systems. Novel fabrication techniques have been developed and employed in order to investigate and control various aspects of the structures, including carrier density and electric fields across the wires

Radiation Tolerant Electronics, Volume II

Research on radiation tolerant electronics has increased rapidly over the last few years, resulting in many interesting approaches to model radiation effects and design radiation hardened integrated circuits and embedded systems. This research is strongly driven by the growing need for radiation hardened electronics for space applications, high-energy physics experiments such as those on the large hadron collider at CERN, and many terrestrial nuclear applications, including nuclear energy and safety management. With the progressive scaling of integrated circuit technologies and the growing complexity of electronic systems, their ionizing radiation susceptibility has raised many exciting challenges, which are expected to drive research in the coming decade.After the success of the first Special Issue on Radiation Tolerant Electronics, the current Special Issue features thirteen articles highlighting recent breakthroughs in radiation tolerant integrated circuit design, fault tolerance in FPGAs, radiation effects in semiconductor materials and advanced IC technologies and modelling of radiation effects

Laser-induced forward transfer (LIFT) of water soluble polyvinyl alcohol (PVA) polymers for use as support material for 3D-printed structures

The additive microfabrication method of laser-induced forward transfer (LIFT) permits the creation of functional microstructures with feature sizes down to below a micrometre [1]. Compared to other additive manufacturing techniques, LIFT can be used to deposit a broad range of materials in a contactless fashion. LIFT features the possibility of building out of plane features, but is currently limited to 2D or 2½D structures [2–4]. That is because printing of 3D structures requires sophisticated printing strategies, such as mechanical support structures and post-processing, as the material to be printed is in the liquid phase. Therefore, we propose the use of water-soluble materials as a support (and sacrificial) material, which can be easily removed after printing, by submerging the printed structure in water, without exposing the sample to more aggressive solvents or sintering treatments. Here, we present studies on LIFT printing of polyvinyl alcohol (PVA) polymer thin films via a picosecond pulsed laser source. Glass carriers are coated with a solution of PVA (donor) and brought into proximity to a receiver substrate (glass, silicon) once dried. Focussing of a laser pulse with a beam radius of 2 µm at the interface of carrier and donor leads to the ejection of a small volume of PVA that is being deposited on a receiver substrate. The effect of laser pulse fluence , donor film thickness and receiver material on the morphology (shape and size) of the deposits are studied. Adhesion of the deposits on the receiver is verified via deposition on various receiver materials and via a tape test. The solubility of PVA after laser irradiation is confirmed via dissolution in de-ionised water. In our study, the feasibility of the concept of printing PVA with the help of LIFT is demonstrated. The transfer process maintains the ability of water solubility of the deposits allowing the use as support material in LIFT printing of complex 3D structures. Future studies will investigate the compatibility (i.e. adhesion) of PVA with relevant donor materials, such as metals and functional polymers. References: [1] A. Piqué and P. Serra (2018) Laser Printing of Functional Materials. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA. [2] R. C. Y. Auyeung, H. Kim, A. J. Birnbaum, M. Zalalutdinov, S. A. Mathews, and A. Piqué (2009) Laser decal transfer of freestanding microcantilevers and microbridges, Appl. Phys. A, vol. 97, no. 3, pp. 513–519. [3] C. W. Visser, R. Pohl, C. Sun, G.-W. Römer, B. Huis in ‘t Veld, and D. Lohse (2015) Toward 3D Printing of Pure Metals by Laser-Induced Forward Transfer, Adv. Mater., vol. 27, no. 27, pp. 4087–4092. [4] J. Luo et al. (2017) Printing Functional 3D Microdevices by Laser-Induced Forward Transfer, Small, vol. 13, no. 9, p. 1602553

Particle Physics Reference Library

This second open access volume of the handbook series deals with detectors, large experimental facilities and data handling, both for accelerator and non-accelerator based experiments. It also covers applications in medicine and life sciences. A joint CERN-Springer initiative, the “Particle Physics Reference Library” provides revised and updated contributions based on previously published material in the well-known Landolt-Boernstein series on particle physics, accelerators and detectors (volumes 21A,B1,B2,C), which took stock of the field approximately one decade ago. Central to this new initiative is publication under full open access

MC 2019 Berlin Microscopy Conference - Abstracts

Das Dokument enthält die Kurzfassungen der Beiträge aller Teilnehmer an der Mikroskopiekonferenz "MC 2019", die vom 01. bis 05.09.2019, in Berlin stattfand

Proceedings of the 2018 Canadian Society for Mechanical Engineering (CSME) International Congress

Published proceedings of the 2018 Canadian Society for Mechanical Engineering (CSME) International Congress, hosted by York University, 27-30 May 2018

ESARDA 37th Annual Meeting Proceedings

The 37th ESARDA symposium on Safeguards and Nuclear Non-Proliferation was held in Manchester, United Kingdom from 19-21 May, 2015. The Symposium has been preceded by meetings of the ESARDA Working Groups on 18 May 2015. The event has once again been an opportunity for research organisations, safeguards authorities and nuclear plant operators to exchange information on new aspects of international safeguards and non-proliferation, as well as recent developments in nuclear safeguards and non-proliferation related research activities and their implications for the safeguards community. The Proceedings contains the papers (118) submitted according to deadlines.JRC.E.8-Nuclear securit

Topical Workshop on Electronics for Particle Physics

The purpose of the workshop was to present results and original concepts for electronics research and development relevant to particle physics experiments as well as accelerator and beam instrumentation at future facilities; to review the status of electronics for the LHC experiments; to identify and encourage common efforts for the development of electronics; and to promote information exchange and collaboration in the relevant engineering and physics communities