Dissertations / Theses on the topic 'Nickel nitrate'

Abstract Water-related problems are increasing globally, and new, low-cost technologies are needed to resolve them. Lignocellulosic waste materials contain reactive functional groups that can be used to provide a bio-based platform for the production of water treatment chemicals. Research on bio-based ion exchange materials in the treatment of real wastewaters is needed. In this thesis, anion exchange materials were prepared through chemical modification (epichlorohydrin, ethylenediamine and triethylamine) using five Finnish lignocellulosic materials as bio-based platforms. Scots pine sawdust and bark (Pinus sylvestris), Norway spruce bark (Picea abies), birch bark (Betula pendula/pubescens) and peat were chosen due to their local availability and abundance. The focus was placed on NO3- removal, but uptake of heavy metals, such as nickel, was also observed and studied. Studies on maximum sorption capacity, mechanism, kinetics, and the effects of temperature, pH and co-existing anions were used to elucidate the sorption behaviour of the prepared materials in batch and column tests. All five materials removed over 70% of NO3- at pH 3–10 (initial conc. 30 mg N/l). Quaternized pine sawdust worked best (max. capacity 32.8 mg NO3-N/g), and also in a wide temperature range (5–70°C). Column studies on quaternized pine sawdust using mining wastewater and industrial wastewater from a chemical plant provided information about the regeneration of exhausted material and its suitability for industrial applications. Uptake of Ni, V, Co and U was observed. Column studies proved the easy regeneration and reusability of the material. For comparison, pine sawdust was also modified using N-(3-chloro-2-hydroxypropyl) trimethylammonium chloride and utilized to remove NO3- from groundwater and industrial wastewater. A maximum sorption capacity of 15.3 mg NO3-N/g was achieved for the synthetic solution. Overall, this thesis provides valuable information about bio-based anion exchange materials and their use in real waters and industrial applications
Tiivistelmä Edullisia ja kestäviä vedenkäsittelytekniikoita tarvitaan kasvavien vesiongelmien ratkaisemiseen. Lignoselluloosaa, kuten sahanpurua, syntyy suuria määriä teollisuuden sivutuotteena. Sen reaktiivisia funktionaalisia ryhmiä voidaan modifioida kemiallisesti ja valmistaa siten biopohjaisia vedenkäsittelykemikaaleja. Tutkimustietoa oikeiden jätevesien puhdistuksesta biopohjaisilla ioninvaihtomateriaaleilla tarvitaan lisää, jotta materiaalien käyttöä voidaan kehittää ja edistää. Tässä väitöstyössä valmistettiin anioninvaihtomateriaaleja modifioimalla kemiallisesti viittä suomalaista lignoselluloosamateriaalia: männyn sahanpurua ja kuorta (Pinus sylvestris), kuusen kuorta (Picea abies), koivun kuorta (Betula pendula/pubescens) ja turvetta. Menetelmässä käytettiin epikloorihydriiniä, etyleenidiamiinia ja trietyyliamiinia orgaanisessa liuotinfaasissa. Työssä keskityttiin erityisesti nitraatin poistoon sekä synteettisistä että oikeista jätevesistä. Materiaalien soveltuvuutta teollisiin sovelluksiin arvioitiin maksimisorptiokapasiteetin, sorptioisotermien, kinetiikka- ja kolonnikokeiden sekä pH:n, lämpötilan ja muiden anionien vaikutusta tutkivien kokeiden avulla. Kaikki viisi kationisoitua tuotetta poistivat yli 70 % nitraatista laajalla pH-alueella (3–10). Kationisoitu männyn sahanpuru osoittautui parhaaksi materiaaliksi (32,8 mg NO3-N/g), ja se toimi laajalla lämpötila-alueella (5–70°C). Kolonnikokeet osoittivat sen olevan helposti regeneroitavissa ja uudelleenkäytettävissä. Tuotetta testattiin myös kaivos- ja kemiantehtaan jäteveden käsittelyyn, ja kokeissa havaittiin hyviä nikkeli-, uraani-, vanadiini- ja kobolttireduktioita. Männyn sahanpurua modifioitiin vertailun vuoksi myös kationisella monomeerilla, N-(3-kloro-2-hydroksipropyyli)trimetyyliammoniumkloridilla. Tuotteen maksimisorptiokapasiteetiksi saatiin 15,3 mg NO3-N/g ja se poisti nitraattia saastuneesta pohjavedestä. Kokonaisuudessaan väitöskirjatyö tarjoaa uutta tietoa biopohjaisten ioninvaihtomateriaalien valmistamisesta ja niiden soveltuvuudesta oikeiden teollisuusjätevesien käsittelyyn

Notre objectif est d'étudier les réactions chimiques et transitions de phases qui peuvent se produire lorsque du nitrate de magnésium, du nitrate de sodium, un précipité de soufre cobalt et du ferrocyanure de nickel potassium sont chauffés ensemble lors du conditionnement de déchets nucléaires par le bitume. La méthodologie appliquée associe plusieurs techniques: la température, l'enthalpie et la cinétique de réaction sont déterminées par calorimétrie, les produits de réaction sont caractérisés par des analyses chimiques, spectrométrie de masse et DRX. Trois domaines de température et d'énergie sont mis en évidence en fonction de la composition (composés seuls ou en mélange). L'étude des réactions de NaNO3 avec le précipité de soufre cobalt permet de montrer l'effet de l'eau sur la température de réaction. Celle entre Mg(NO3)2, 6 H20 avec CoS indique que différents phénomènes thermiques se superposent et que la cinétique de réaction est lente (plusieurs heures)
This work deals with the study of chemical reactions and phases transitions which can occur between magnesium nitrate, sodium nitrate, cobalt sulphur product, and nickel potassium ferrocyanide, when they are heated together during bituminisation process of nuclear waste. The applied methodology associates a few techniques: temperature, enthalpy, and kinetics of reaction are determined by calorimetry, reaction products are characterised by chemical analyses, mass spectrometry and XRD analysis. Three fields of temperature and energy are observed in function of composition (one compound or a mixture of compounds). The study of reactions between NaNO3 and cobalt sulphur product shows that the presence of water has got an effect on reaction temperature. The study of Mg(NO3)2, 6 H20 and CoS shows an overlapping of different signals, and that the reaction rate is very slow (a few hours)

Ces travaux de recherche sont dédiés à l’élaboration, par un même et unique procédé, des différentes couches (électrolyte / anode / cathode) entrant dans la composition des piles à combustibles à oxyde solide (S. O. F. Cs : Solid Oxide Fuel Cells). L’électrolyte en zircone yttriée (Y. S. Z. : Yttria Stabilised Zirconia) doit présenter une microstructure dense (imperméable aux gaz) d’une épaisseur comprise entre 5 et 20 µm, tandis que les électrodes doivent être poreuse et plus épaisses (200-500 µm), en Ni-Y. S. Z. (anode) et LaMnO 3 (cathode). La technique choisie pour atteindre ces objectifs est le procédé de projection par plasma d’arc soufflé, à pression atmosphérique, de céramiques ou de métaux injectés par voie liquide (précurseur ou suspension de poudre micrométrique ou sub-micronique). Pour mener à bien ces travaux, une bonne compréhension des phénomènes mis en jeu (paramètres plasma, injection de liquide, pénétration du jet de liquide et traitement de la suspension dans le plasma, nature et granulométrie des poudres employées pour la réalisation des suspensions,…) est nécessaire, et des modèles simples ont été utilisés pour déterminer des ordres de grandeurs et expliquer les résultats expérimentaux. Ces travaux ont ainsi permis la réalisation d’électrolytes denses d’épaisseurs comprises entre 5 et 20 µm et d’électrodes poreuses finement structurés. De plus, les premiers résultats sur la réalisation d’assemblage de ces différentes couches (électrolyte-cathode et électrolyte-anode) sont très prometteurs
The aim of this PhD work is the elaboration, by a same process, of the different constituents (electrolyte / anode / cathode) of Solid Oxyde Fuell Cells (S. O. F. Cs ). The yttria stabilised zirconia electrolyte (Y. S. Z. ) should present a dense microstructure (gas impervious) with a thickness included betwen 5 and 20 µm, whereas the electrodes shoud be porous and thicker (200-500 µm), in Ni-Y. S. Z. (anode) and LaMnO 3 (cathode). The chosen process to reach these goals is the direct current plasma jet projection, under atmospheric pressure, of ceramics or metals by liquid injection (liquid precursor or micronic or submicronic powder suspensions). To bring this work to a successful conclusion, a good understanding of the acting event (plasma parameters, liquid injection, plasma liquid jet penetration and plasma suspension treatment, kind and granulometry of the powder used for the suspension production,…) is necessary, and simple models have been used in order to determine some magnitudes and explain experimental results. These works have also allowed the elaboration of dense electrolytes with a thickness included between 5 and 20 µm and finely structured porous electrodes. Moreover, the first results on multi layered production of the fuel cell constituent (electrolyte-cathode and electrolyte-anode) are likely

In recent years there has been a huge increase in the growth of communication systems such as mobile phones, wireless local area networks (WLAN), satellite navigation and various other forms of wireless data communication that have made analogue frequency control a key issue. The increase in frequency spectrum crowding and the increase of frequency into microwave region, along with the need for minimisation and capacity improvement, has shown the need for the development of high performance, miniature, on-chip filters operating in the low to medium GHz frequency range. This has hastened the need for alternatives to ceramic resonators due to their limits in device size and performance, which in turn, has led to development of the thin film electro-acoustics industry with surface acoustic wave (SAW) and bulk acoustic wave (BAW) filters now fabricated in their millions. Further, this new technology opens the way for integrating the traditionally incompatible integrated circuit (IC) and electro-acoustic (EA) technologies, bringing about substantial economic and performance benefits. In this thesis the compatibility of aluminium nitride (AlN) to IC fabrication is explored as a means for furthering integration issues. Various issues have been explored where either tailoring thin film bulk acoustic resonator (FBAR) design, such as development of an improved solidly mounted resonator (SMR) technology, and use of IC technology, such as chemical mechanical polishing (CMP) or nickel silicide (NiSi), has made improvements beneficial for resonator fabrication or enabled IC integration. The former has resulted in major improvements to Quality factor, power handling and encapsulation respectively. The later has provided alternative methods to reduce electro- or acoustomigration, reduced device size, for plate waves, supplied novel low acoustic impedance material for high power applications and alternative electrodes for use in high temperature sensors. Another method to enhance integration by using the piezoelectric material, AlN, in the IC side has also been explored. Here methods for analysing AlN film contamination and stoichiometry have been used for analysis of AlN as a high-k dielectric material. This has even brought benefits in knowledge of film composition for use as a passivation material with SiC substrates, investigated in high power high frequency applications. Lastly AlN has been used as a buried insulator material for new silicon-on-insulator substrates (SOI) for increased heat conduction. These new substrates have been analysed with further development for improved performance indicated.
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Thesis (Ph. D.)--Ohio State University, 2004.
Title from first page of PDF file. Document formatted into pages; contains xxii, 182 p.; also includes graphics (some col.). Includes abstract and vita. Advisor: Leonard J. Brillson, Dept. of Electrical Engineering. Includes bibliographical references (p. 173-182).

L'objectif de ce travail est double : 1) etudier les liaisons chimiques formees par implantation d'ions ti, fe et co dans zrn, sic et si 3n 4 ; 2) coupler les proprietes structurales et magnetiques d'agregats de nickel et de cobalt, en matrice ain, prepares par implantation ionique ou depots de couches minces par pulverisation cathodique. L'analyse par absorption x au seuil k de l'espece implantee dans zrn, sic et si 3n 4, a permis de montrer que les liaisons chimiques formees au cours de l'implantation pouvaient etre predites dans le cadre d'un modele de chaleur de reaction. L'absorption x et la diffraction de rayons x en incidence rasante sur les echantillons implantes ain/ni et ain/co ont confirme la presence d'agregats metalliques et permis de preciser leur structure cristallographique (ni cfc, co cfc et hcp). Les diametres varient de 1 a 4 nm en fonction de la fluence et du recuit. La presence de pics satellites dans les diagrammes de diffraction pour les echantillons ain/ni et zrn/co recuits, permet de determiner une taille moyenne en accord avec les mesures d'absorption x et de deduire les distances entre agregats. Ces satellites resultent d'une orientation preferentielle des agregats due au recuit. Dans les multicouches ain/co, les atomes de cobalt forment des liaisons avec les voisins aluminium pour des epaisseurs de cobalt inferieures a 0. 7 nm. Pour des epaisseurs plus grandes (1. 5 nm et 3 nm), on observe la formation de couches granulaires. Les mesures d'aimantation realisees a basse temperature par magnetometrie squid et dichroisme circulaire magnetique de rayons x, indiquent que pour le ni et le co, le moment magnetique par atome est inferieur a la valeur du massif et diminue d'un facteur deux quand le diametre des agregats diminue d'un facteur dix. Nous interpretons cette diminution comme un resultat de l'interaction des atomes en bord d'agregats avec les atomes d'aluminium.

Doctor of Philosophy
Department of Chemical Engineering
James H. Edgar
Hexagonal boron nitride (hBN) is a wide bandgap III-V semiconductor that has seen new interest due to the development of other III-V LED devices and the advent of graphene and other 2-D materials. For device applications, high quality, low defect density materials are needed. Several applications for hBN crystals are being investigated, including as a neutron detector and interference-less infrared-absorbing material. Isotopically enriched crystals were utilized for enhanced propagation of phonon modes. These applications exploit the unique physical, electronic and nanophotonics applications for bulk hBN crystals. In this study, bulk hBN crystals were grown by the flux method using a molten Ni-Cr solvent at high temperatures (1500°C) and atmospheric pressures. The effects of growth parameters, source materials, and gas environment on the crystals size, morphology and purity were established and controlled, and the reliability of the process was greatly improved. Single-crystal domains exceeding 1mm in width and 200μm in thickness were produced and transferred to handle substrates for analysis. Grain size dependence with respect to dwell temperature, cooling rate and cooling temperature were analyzed and modeled using response surface morphology. Most significantly, crystal grain width was predicted to increase linearly with dwell temperature, with single-crystal domains exceeding 2mm in at 1700°C. Isotopically enriched ¹⁰B and ¹¹B hBN crystal were produced using a Ni-Cr-B flux method, and their properties investigated. ¹⁰B concentration was evaluated using SIMS and correlated to the shift in the Raman peak of the E[subscript 2g] mode. Crystals with enrichment of 99% ¹⁰B and >99% ¹¹B were achieved, with corresponding Raman shift peaks at 1392.0 cm⁻¹ and 1356.6 cm⁻¹, respectively. Peak FWHM also decreased as isotopic enrichment approached 100%, with widths as low as 3.5 cm⁻¹ achieved, compared to 8.0 cm⁻¹ for natural abundance samples. Defect selective etching was performed using a molten NaOH-KOH etchant at 425°C-525°C, to quantify the quality of the crystals. Three etch pit shapes were identified and etch pit width was investigated as a function of temperature. Etch pit density and etch pit activation energy was estimated at 5×10⁷ cm⁻² and 60 kJ/mol, respectively. Screw and mixed-type dislocations were identified using diffraction-contrast TEM imaging.

La reduction catalytique en phase liquide du valeronitrile a ete etudiee sur nickel de raney dans le but d'obtenir selectivement l'amine primaire. L'effet de differents parametres de reaction sur la vitesse d'hydrogenation et la selectivite a ete examine et a permis de confirmer le reseau reactionnel complexe avec reversibilite des reactions. Des catalyseurs non dopes ou promus avec des elements metalliques (cr, fe, co, mo, ti. . . ) ont ete prepares a partir des phases metallurgiques ni#2al#3 ou nial#3. Les alliages et les catalyseurs ont ete caracterises par analyse chimique, stem-edx, xps, spectroscopie auger. . . Les dopants fer et chrome ameliorent l'activite et la selectivite du catalyseur, quel que soit l'alliage de depart, la reduction de la dipentylimine intermediaire sur ces memes catalyseurs a permis d'expliquer les ameliorations de selectivite observees en reduction du valeronitrile. L'adsorption du valeronitrile et de ses produits d'hydrogenation sur ces catalyseurs a ete effectuee en phase liquide. Le nitrile et l'amine s'adsorbent sur des sites differents; l'adsorption de valeronitrile est liee a la quantite d'hydrogene chimisorbe

La dénitrification autotrophe à l’aide de composés réduit de soufre est une approche intéressante pour le traitement biologique des contaminations azotées et des effluents pauvre en matière organique. La dénitrification autotrophe utilise des composés inorganiques comme sources d'énergie et de carbone. L'absence de matière organique élimine le besoin de post-traitements pour éliminer l'excès de carbone organique et limite la formation sous-produits d’oxydation dans le cadre de la production d’eau potable. Les eaux usées provenant des industries métallurgiques et minières ont généralement un faible pH, des températures basses et des concentrations élevées en métaux lourds. L'élimination biologique de l'azote est un défi parce que les bactéries dénitrifiantes prospèrent habituellement à pH neutre et à températures ambiantes (20-30 °C).Le but de cette thèse était de développer un procédé robuste de dénitrification à base de soufre dans des bioréacteurs à pH acide, températures psychrophiles (< 20 °C) et concentrations élevées en nickel. Le procédé a été optimisé au préalable avec des essais biologiques étudiant l'influence de la source de soufre (S2O32-, S0 biogénique et le synthétisé chimiquement), de la taille des particules de S0 (poudre et lentilles), de la culture dénitrifiante (cultures pures et mixtes de Thiobacillus) et de la température (6-30 °C) sur la cinétique de la dénitrification. L'utilisation de S2O32- et d’une culture pure de T. denitrificans ont permis d’atteindre des rendements de dénitrification les plus élevés. Le soufre élémentaire biogénique a été testé pour la première fois comme donneur d'électrons pour la dénitrification, montrant des taux de dénitrification 1.7 fois plus élevés que ceux obtenue avec de la poudre de S0 synthétisé chimiquement. Les taux de la dénitrification avec le S2O32- augmentent exponentiellement avec la température et les calculs avec l'équation d'Arrhenius donnent une énergie d'activation apparente Ea de 76.6 kJ/mol.Deux réacteurs à lit fluidisé (FBR) ont été utilisés pour étudier la dénitrification avec S2O32- à différents pH (5.25-7.00) et températures décroissantes (3-20 °C). Des rendements de dénitrification > 99% ont été observés pour eaux usés présentant des pH compris entre 5.75 et 5.30. L'addition d'une unité de carbonatation fournissant au biofilm du CO2 comme source de carbone supplémentaire, permettant une dénitrification complète à un pH de 4.75. Dans le même FBR, des taux de charge d'azote élevés (jusqu'à 3,3 kg N-NO3-/m3 d) avec le thiosulfate ont été maintenu à des températures aussi basses que 3 °C. L'impact de deux composés du Nickel (NiEDTA2- et NiCl2) sur la dénitrification à base de soufre a été étudiée dans deux FBR en parallèle à 20 (± 2) °C et des concentrations de nickel variant dans la gamme de 5-200 mg Ni/L. Dans des bioessais discontinues, 25-100 mg Ni/L de NiCl2 ont inhibée l'élimination de NO3- de 7-16%, alors qu'aucune inhibition n'a été observée avec NiEDTA2-. L'EDTA non complexée a inhibée la dénitrification à des concentrations supérieures à 100 mg/L. Les deux composés de Ni ont montré aucun effet négatif sur la dénitrification en FBR aux concentrations testées. Le bilan massique du nickel, la caractérisation de la phase solide et la modélisation thermodynamique ont révélé que des précipités de nickel ont été principalement éliminés avec l'effluent. Les phosphates, sulfures et oxydes de nickel ont été déterminés comme les principaux précipités de nickel et étaient principalement amorphe.Les FBRs se sont révélés être bioprocédés robustes pour l'élimination de l'azote à pH acide, pour des températures psychrophiles et des concentrations élevées de nickel. Les résultats de cette étude sont d'un grand intérêt pour le traitement des eaux souterraines et minières contaminés par les nitrates dans les régions froides du monde et également pour les eaux usées industrielles acides et chargées en métaux lourds
Autotrophic denitrification driven by reduced sulfur compounds is a promising and cost-effective biological nitrogen removal process, recommended for the treatment of organic-deficient waters, e.g. groundwater and several industrial wastewaters. Autotrophic denitrifiers utilize inorganic compounds as sources of energy and carbon. The lack of organics eliminates the need of post-treatments to remove excess organic carbon and limits the formation of harmful organic byproducts (e.g. trihalomethanes, THM), resulting in a clean and safe treatment also for drinking water. Wastewaters from mining and metal-finishing industry commonly feature low pH and temperatures as well as high heavy metal concentrations. Nitrogen removal from these waters is a technical challenge, since denitrifying bacteria usually thrives at circumneutral pH and ambient temperatures (20-30°C).The aim of this study was to develop a robust and efficient sulfur-based denitrification bioreactor process able to tolerate acidic pH, psychrophilic temperatures (< 20°C) and high nickel concentrations. The process was preliminary optimized in batch bioassays investigating the influence of sulfur source, i.e. thiosulfate (S2O32-) and biogenic and chemically synthesized elemental sulfur (S0), S0 particle size (powder and lentils), denitrifying culture (pure and mixed cultures of Thiobacillus) and temperature (6-30°C) on denitrification kinetics. The use of S2O32- and a pure culture of Thiobacillus denitrificans resulted in the highest denitrification rates. Biogenic S0 was tested for the first time as electron donor for autotrophic denitrification, showing 1.7-fold faster NO3- removal than that achieved with chemically synthesized S0 powder. The rates of thiosulfate-driven denitrification exponentially increased with temperature, being modeled according to the Arrhenius equation with an apparent activation energy Ea of 76.6 kJ/mol and a temperature coefficient Q10 of 3.0.Fluidized-bed reactors (FBRs) were used to investigate continuous thiosulfate-driven denitrification under decreasing feed pH (5.25-7.00) and temperatures (3-20°C). Denitrification efficiencies > 99% were observed at feed and effluent pH as low as 5.75 and 5.30, respectively. At lower feed pH values, the denitrification activity rapidly decreased due to an inorganic carbon deficiency. The addition of a carbonation unit providing CO2 as supplemental carbon source to the FBR biofilm allowed complete denitrification even at a pH of 4.75. In the same FBR, high-rate (up to 3.3 kg N-NO3-/m3 d) thiosulfate-driven denitrification was maintained at temperatures as low as 3°C. The impact of two Ni compounds, i.e. NiEDTA2- and NiCl2, on sulfur-based denitrification was investigated in a parallel FBR at 20 (±2)°C and feed Ni concentrations in the range of 5-200 mg Ni/L. Preliminary batch bioassays were carried out to assess Ni and free EDTA toxicity on sulfur-based denitrification. In batch bioassays, 25-100 mg Ni/L of NiCl2 inhibited NO3- removal by 7-16%, whereas no inhibition was observed with NiEDTA2-. Free EDTA inhibited sulfur-based denitrification at concentrations exceeding 100 mg/L. Both Ni compounds showed no detrimental effects on sulfur-based denitrification in FBR at the tested concentrations. Nickel mass balance, solid-phase characterization and thermodynamic modeling revealed that nickel precipitates were mostly washed out with the effluent, due to the slow Ni precipitation kinetics and high upflow velocities in the FBR. Nickel phosphate, sulfide and oxide were indicated as the main nickel precipitates and were mostly amorphous.FBRs were shown to be powerful and robust biofilm systems for nitrogen removal under acidic pH, psychrophilic temperatures and high nickel concentrations. The results of this study are of great interest for the treatment of NO3- contaminated ground and mining waters in cold regions (e.g. Canadian and Scandinavian regions) as well as acidic and heavy-metal-laden wastewaters

Neste trabalho investigou-se a influência do cobre em diferentes catalisadores a base de níquel na decomposição catalítica do metano. Foram avaliados desde aspectos relacionados ao tratamento térmico das amostras até o desempenho catalítico nos testes de atividade. As amostras foram preparadas a partir de dois métodos diferentes. Um grupo foi preparado pelo método de impregnação úmida utilizando sílica como suporte, enquanto o segundo foi preparado pelo método de coprecipitação contínua, utilizando nitratos de cobre, níquel e alumínio em diferentes composições molares. Os ensaios foram realizados em reator tubular de leito fixo acoplado a um forno com controle de temperatura e conectado em linha com cromatógrafo gasoso. Utilizou-se 100 mg de amostra, numa faixa de temperatura de 500 a 750°C, utilizando como alimentação uma mistura reacional de N2:CH4 na proporção de 9:1. A caracterização das amostras foi realizada através das análises de SBET, TGA, TPR, TPO, DRX e Espectroscopia Raman. Os resultados mostraram uma significativa influência do cobre na atividade das amostras em temperaturas superiores a 500°C. A presença de cobre influenciou a área específica e a temperatura de redução das amostras calcinadas. Pequenas quantidades de cobre contribuem ao evitar a desativação do catalisador por sinterização em temperaturas superiores a 500°C. Para os catalisadores coprecipitados, além da influência do cobre, avaliou-se também a influência do gás utilizado no tratamento térmico das amostras. Foram utilizadas amostras não calcinadas, amostras calcinadas em ar por seis horas e calcinadas em N2 pelo mesmo período. Os resultados indicaram que a presença de cobre contribui para uma maior estabilidade e atividade nos ensaios realizados nas temperaturas de 600 e 650°C, principalmente para as amostras calcinadas em ar. As amostras com 11% de cobre na composição apresentaram elevada estabilidade na temperatura de 600°C, mesmo quando não calcinadas, indicando que a etapa de tratamento térmico pode ser evitada para este tipo de amostra. As análises de DRX, TPO e Espectroscopia Raman sugerem que o carbono formado, tanto para os catalisadores suportados quanto para os coprecipitados, depositou-se na forma de nanotubos de paredes múltiplas.
The effect of copper in different nickel-based catalysts in the catalytic decomposition of methane was investigated. Were evaluated aspects from the heat treatment of the samples to the catalytic performance in activity tests. Samples were prepared using two different methods. One group was prepared by the wet impregnation method using silica as the support and the second group was prepared by continuous coprecipitation method using copper nitrate, nickel and aluminum in different molar compositions. Catalytic activity runs were carried out in a tubular fixed-bed reactor coupled to an oven with temperature control and connected in line with a gas chromatograph. Samples of 100 mg were used in a temperature range of 500 to 750°C applying a reaction mixture of N2:CH4 at a ratio 9:1 as feed supply. The characterization of the samples was performed through the analysis of SBET, TGA, TPR, TPO, XRD and Raman spectroscopy. The results showed a significant effect of copper on the activity of the samples at temperatures above 500°C. The presence of copper influenced the specific area and the reduction temperature of the calcined samples. Small amounts of copper contributed to avoid catalyst deactivation by sintering at temperatures above 500°C. For the coprecipitated catalysts in addition to the influence of copper, the effect of the gas used for the thermal treatment of samples was also evaluated. Uncalcined samples and samples calcined in air and in N2 for six hours were used. The results indicated that the presence of copper contributed to a superior stability and activity in runs performed at temperatures of 600 to 650°C, especially for samples calcined in air. Samples with 11% of copper showed high stability at 600°C, even if not calcined, indicating that the thermal treatment step can be avoided for this type of sample. The XRD, TPO and Raman spectroscopy results suggest that the carbon deposited on the spent catalysts was in the form of multi-walled nanotubes, for both the supported and the coprecipitated catalysts.

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Nickel alloys are frequently used in applications that require resistance at high temperatures associated with resistance to corrosion. Alloys of Ni-Si-C can be obtained by means of powder metallurgy in which powder mixtures are made of metallic nickel powders with additions of various alloying carriers for such were used in this study SiC, Si3N4 or Si metal with graphite. Carbonyl Ni powder with mean particle size of 11 mM were mixed with 3 wt% of SiC powders with an average particle size of 15, 30 and 50 μm and further samples were obtained containing 4 to 5% by mass of SiC with average particle size of 15 μm. Samples were also obtained by varying the carrier alloy, these being Si3N4 powder with graphite, with average particle size of 1.5 and 5 μm, respectively. As a metallic Si graphite with average particle size of 12.5 and 5 μm, respectively. The reference material used was nickel carbonyl sintered without adding carriers. Microstructural characterization of the alloys was made by optical microscopy and scanning electron microscopy with semi-quantitative chemical analysis. We determined the densities of the samples and measurement of microhardness. We studied the dissociation of carriers alloy after sintering at 1200 ? C for 60 minutes. Was evaluated also in the same sintering conditions, the influence of the variation of average particle size of the SiC carrier to the proportion of 3% by mass. Finally, we studied the influence of variation of the temperatures of sintering at 950, 1080 and 1200 ? C without landing and also with heights of 30, 60, 120 and 240 minutes for sintering where the temperature was 950 ?C. Dilatometry curves showed that the SiC sintered Ni favors more effectively than other carriers alloy analyzed. SiC with average particle size of 15 μm active sintering the alloy more effectively than other SiC used. However, with the chemical and morphological analyzes for all leagues, it was observed that there was dissociation of SiC and Si3N4, as well as diffusion of Si in Ni matrix and carbon cluster and dispersed in the matrix, which also occurred for the alloys with Si carriers and metallic graphite. So the league that was presented better results containing Si Ni with graphite metallic alloy as carriers, since this had dispersed graphite best in the league, reaching the microstructural model proposed, which is necessary for material characteristic of solid lubricant, so how we got the best results when the density and hardness of the alloy
Ligas de N?quel s?o freq?entemente utilizadas em aplica??es que requerem resist?ncia mec?nica a elevadas temperaturas associada ? resist?ncia ? corros?o. Ligas de Ni-Si-C podem ser obtidas por meio de metalurgia do p? em que s?o realizadas misturas de p?s de n?quel met?lico com adi??es de p?s de diferentes portadores de liga, para tal foram utilizados neste trabalho SiC, Si3N4 ou Si met?lico com grafita. P?s de Ni carbonila com tamanho m?dio de part?culas de 11 μm foram misturados a 3% em massa de p?s de SiC com tamanho m?dio de part?culas de 15, 30 e 50 μm e foram obtidas ainda amostras contendo 4 e 5% em massa de SiC com tamanho m?dio de part?culas de 15 μm. Tamb?m foram obtidas amostras variando-se o portador de liga, sendo estes p?s de Si3N4 com grafita, com tamanho m?dio de part?culas de 1,5 e 5 μm, respectivamente. Assim como Si met?lico com grafita, com tamanho m?dio de part?culas de 12,5 e 5 μm, respectivamente. O material de refer?ncia adotado foi n?quel carbonila sinterizado sem adi??o de portadores. A caracteriza??o microestrutural das ligas foi feita por microscopia ?ptica e eletr?nica de varredura com an?lise qu?mica semi-quantitativa. Foram determinadas as densidades das amostras e obtidas medidas de microdureza Vickers. Foi estudada a dissocia??o dos portadores de liga ap?s sinteriza??o em 1200 ?C durante 60 minutos. Foi avaliada, ainda, para as mesmas condi??es de sinteriza??o, a influencia da varia??o do tamanho m?dio de part?culas do portador SiC, para a propor??o de 3% em massa. Por fim, foi estudo a influencia da varia??o das temperaturas de sinteriza??o em 950, 1080 e 1200 ?C sem patamar e, ainda, com patamares de 30, 60, 120 e 240 minutos para sinteriza??o cuja temperatura foi de 950 ?C. As curvas de dilatometria mostraram que o SiC favorece a sinteriza??o do Ni de forma mais eficaz que os demais portadores de liga analisados. O SiC com tamanho m?dio de part?culas de 15 μm ativa a sinteriza??o da liga de forma mais eficaz que os demais SiC utilizados. Por?m, com as an?lises qu?mica e morfol?gica para todas as ligas, foi poss?vel observar que houve dissocia??o do SiC e do Si3N4, assim como difus?o do Si na matriz de Ni e carbono aglomerado e disperso na matriz, o que tamb?m ocorreu para as ligas com portadores Si met?lico e grafita. Portanto, a liga que apresentou melhores resultados foi de Ni contendo Si met?lico com grafita como portadores de liga, j? que esta apresentou grafita melhor dispersa na liga, atingindo o modelo microestrutural proposto, do qual ? necess?rio para material com caracter?stica de lubrificante s?lido, assim como obteve os melhores resultados quando a densidade e dureza da liga

Per la realizzazione di questo studio sono stati cercati i dati riguardanti le caratteristiche chimico-fisiche delle acque sotterranee raccolti dalle ARPA di Piemonte, Lombardia, Veneto, Friuli-Venezia Giulia ed Emilia-Romagna nel 2018. I dati ottenuti sono stati elaborati per costituire un unico database e, per ottenere questo risultato, è stato necessario omogeneizzare il più possibile i dati originali, che erano eterogenei in termini di parametri analizzati, completezza dei dati, coordinate geografiche dei punti di campionamento e limiti di rilevabilità individuati per ciascun elemento. Sono stati stabiliti sei gruppi di campioni, distinti in funzione della tipologia di acquifero in cui circolano le acque (freatico, semiconfinato, confinato) e della stagione di campionamento (primavera-estate, autunno- inverno). I campioni sono stati classificati in funzione della temperatura, del pH, della durezza e della conducibilità elettrica. Le acque sono state classificate in funzione degli ioni dominanti tramite diagrammi di Langelier-Ludwig e sono stati analizzati, tramite cartografie, i principali ioni disciolti, per valutare l’origine delle acque. Sono state valutate anche le concentrazioni di NO3-, NH4+, Fe2+, Mn2+, As3+, Crtotale, Cr VI, Ni2+, Zn2+. Le acque sono state classificate prevalentemente come Ca-HCO3 e Ca-Mg-HCO3 (90%). A livello locale sono state rilevate acque Na-HCO3, Mg-HCO3, Ca-SO4, Na-Cl e Ca-Cl. Negli acquiferi freatici sono state riscontrate contaminazioni da NO3- ed elevate concentrazioni di Na+, K+ e NH4+ attribuibili a fonti antropiche. Negli acquiferi confinati sono stati rilevati valori superiori ai limiti normativi di NH4+, Fe2+, Mn2+, As3+, riconducibili a processi naturali di degradazione della materia organica. Lo stesso è stato riscontrato per il cromo e il nichel, rilevati in concentrazioni elevate in corrispondenza di affioramenti ofiolitici. Non sono state trovate giustificazioni per gli elevati valori di Zn.

L'objectif était d'évaluer l'impact du changement global sur les écosystèmes aquatiques au cours du 21ème siècle, dans le bassin Adour Garonne (S-O France). Une approche de " downscaling " a été développée à l'interface entre les sciences du climat, de l'hydro-chimie et de l'écologie. Les résultats suggèrent une augmentation globale des débits hivernaux ainsi que des débits d'étiages plus faibles. Les concentrations en nitrate pourraient augmenter, de même que la distribution des espèces de poissons les plus thermophiles. Toutefois, une diminution des gaz à effet de serre ainsi qu'une modification des pratiques agricoles (ex. Diminution des fertilisants azotés) pourraient limiter l'intensité des perturbations écologiques. Cette thèse offre une contribution originale, notamment pour la gestion future des ressources hydriques et écologiques
This thesis aimed at assessing the impact of global change on freshwater ecosystems during the 21st century in the Adour Garonne area (SW France). A downscaling approach was developed linking techniques from climate, hydro-chemical and ecological sciences. The main results suggest an increase of high flows in winter as well as more severe low flows in summer. Nitrogen concentrations and thermophile fish species distribution may also increase. Reducing green house gas emissions and modifying agricultural practices (e. G reducing nitrate fertilizers) could reduce the intensity of ecological disturbances. This study is an original contribution to the management of future hydrological and ecological resources

Competition between plant individuals and how plants alter soil properties are key processes which drive changes in plant communities over time. Estimating the relative importance of these processes and how they affect plant growth in different ecological contexts and communities is an active area of research. Furthermore, interdependencies between the two processes have been suggested to occur in many cases, but research in this area is also lacking. In this study, soil conditioned by common yarrow (Achillea millefolium) was collected from field plots and was then used in a growth chamber competition experiment, which controlled for plant-soil feedbacks. Measured soil properties such as soil pH, soil nitrogen, and soil texture were primarily used as background data in the experiment. Field parameters such as light availability, plant density, and grass to forbs ratio were used to predict optimal A. millefolium habitat in relation to other vascular plant species. The results indicate that A. millefolium was a weaker competitor than cornflower (Centaurea cyanus), while a positive plant-soil feedback effect was observed by A. millefolium grown in field soil. Intraspecific competition had a strong negative effect on A. millefolium growth when grown in non-conditioned soil, but not when grown in A. millefolium conditioned soil. Finally, competition and plant-soil feedbacks appeared to be additively affecting A. millefolium growth, meaning the plant-soil feedback effect did not have a disproportionate effect on competitive outcomes, or vice versa. The findings of this study can be of interest to conservationists or farmers who wish to predict how plant communities respond to plant competition and plant-soil feedbacks as processes.

碩士
元智大學
化學工程與材料科學學系
95
Recent advance in technology has led to serious wasterwater pollution in Taiwan. As a result, many nitrate/nitrite wastewater treatment technologis has been evolved eventually. Therefore, the main objective of this research was to synthesize the nickel (Ni) or zinc (Zn) ferrites (Ni- or Zn-Fe2O4) and to reduce the concentration of nitrate/nitrite contaminants in wastewaters. The current research can be divided into four sections including synthesis of ferrites, application of ferrites on nitrate/nitrite contaminants removal, regeneration, and recycle or reuse of ferrite nanoparticles. Moreover, the kinetic parameters got by pseudo-first-order model equation were also found. Experimentally, nickel or zinc ferrite nanoparticles were synthesized under hydrothermal conditions (pH = 8.5, T = 453 K, and mixing rate of 1250 rpm) by precipitating from metal nitrates with aqueous ammonia. Synthesized nanopowders were characterized by X-ray powder diffractometer (XRPD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), BET surface area and porosimeter, electron spectroscopy for chemical analysis (ESCA), Fourier transform infrared spectrometer (FTIR), extended X-ray absorption fine structure (EXAFS), X-ray absorption near edge structure (XANES), ultraviolet-visible spectrophotometer (UV/Vis), and particle size meter. These results showed that the pore sizes of Ni, Zn-Fe2O4 were about 50-100 nm with spinal structure. Ni, Zn-Fe2O4 having strong characteristic peaks at 2θ = 35.66 and 35.24 were investigated by XRPD patterns, respectively. The specific surface area of Ni, Zn-Fe2O4 measured by ASAP isotherms were 100.4 and 170.7 m2/g, respectively. From ESCA spectra, the results showed that the Fe(2p) of Ni, Zn-Fe2O4 were at 711.05 and 711.25 eV respectively, Ni(2p) of NiFe2O4 were at 855.3 eV, Zn(2p) of ZnFe2O4 were at Zn(4) = 1021.95 eV, and Zn(6) = 1023.08 eV, respectively. By using FTIR spectra, the results showed that the characteristic peaks of Ni, Zn-Fe2O4 were about at 571 and 593 cm-1, respectively, the O-H characteristic peaks of Ni, Zn-Fe2O4 were at 1382 and 1380 cm-1, respectively. The XANES/EXAFS spectra showed that the valencies of the Ni, Zn-Fe2O4 were Ni(II) and Zn(II), respectively. The first shell of Fe-O bonding for Ni, Zn-Fe2O4 with bond distances were 1.95 and 1.94 Å and coordination numbers of 4.03 and 3.81, respectively before hydrogen reduction. Similarly, the first shell of Fe-O bonding for Ni, Zn-Fe2O4 with bond distances were 1.98 and 2.03 Å and coordination numbers of 4.03 and 3.81 respectively after hydrogen reduction at 573 K and 1 atm. The decomposition of nitrate or nitrite contaminants analyzed by UV/Vis was investigated by oxygen-deficient Ni, Zn-Fe2O4 formed by hydrogen reduction at 573 K and 1 atm. As indicated by the results from XRPD, TEM and FE-SEM, the fine structure of Ni, Zn-Fe2O4 did not change after the reaction. In terms of nitrate and nitrite wastewater treatment, the decomposition rates of Zn-ferrites were more efficient than the ones of Ni-ferrites at optimum operating condition at pH = 5 in room temperature. Reaction process described by pseudo-first-order model equation and the k value was increased while the wastewater concentration decreased. The optimized operating conditions were also applied on wasterwater treatment plants, it was found that Zn-ferrites were more efficient than the ones of Ni-ferrite nanoparticles. As shown by XRPD, TEM and FE-SEM analyses, the structure of Ni, Zn-Fe2O4 is very stable and can be recycled. The recyclibility rates of Ni, Zn-Fe2O4 were 98.25 and 98.36% repectively. Thus, the outcome of this study would be able to be applied on existing wasterwater treatment so as to improve the efficiencies of the processes.

碩士
中山醫學院
醫學研究所
87
English abstract Copper, manganese, nickel and lead are widely distributed in the biosphere, being released into the atmosphere by degreasing from the earth crusts and the oceans. In addition, these metals are released into the environment by human activities, such as combustion of fossil fuels and other industrial release. Recent studies suggest that semiconductor workers have an increased incidence of worker-related illness. Semiconductor manufacturing is a chemically intensive industry involving many potentially hazardous operations, the relatively high toxicity of compounds routinely handled by employees. The important health effects of major solvents, acids, caustics, reactive gases, metals, energy and dopands were evaluated by many authors, whereas there are few studies on metals-induced cytogenotoxicities in cultured mammalian cells. In this study, the frequency of micronuclei (MN) was assayed to evaluate the genotoxic effects of Cu2+, Mn2+, Ni2+ and Pb2+ in V79 Chinese hamster lung (V79) cells. The cytotoxic effects of the four heavy metals were conducted by using MTT assay, and nuclear division index (NDI) index. In addition, effects of the four heavy metals on cell cycle distribution and apoptosis in V79 lung cells were assayed by flow cytometry. We also studied the cytogenotoxic interactions of the four heavy metals with Sb3+, In3+, Ca2+ or Mg2+, respectively. Since D-PA and BAL are metal chelators and have been widely used as antidotes in cases of heavy metal poisoning, we also studied the effects of D-PA and BAL on metals-induced cytotoxicity in V79 cells. All of Cu2+, Mn2+ and Ni2+ at higher concentrations (1mM Cu2+; 200-300μM Mn2+; 0.3-1mM Ni2+) significantly increased MN frequencies in V79 cells in this study. However, Pb2+ at lower concentrations of 0.1-3μM significantly increased MN frequencies, but Pb2+-induced genotoxicity was not in a concentration-dependent manner. The results suggested that Pb2+ induced genotoxicity in V79 cells with more specific effect. The results of genotoxic interactions of the four metals with In3+ or Sb3+ were complication: Ni2+ decreased In3+-induced genotoxicity, Cu2+ increased Sb3+-induced genotoxicity, but genotoxic interactions between other metals were not significant. In addition, Ca2+ decreased Pb2+-induced genotoxicity. Mg2+ reversed the genotoxicity of Mn2+ or Pb2+ to the control level, respectively. It appears that both Mn2+- and Pb2+-induced genotoxicity might relate to interfere the biological functions of Mg2+ and Ca2+. Cu2+ (1mM), Mn2+ (200-300μM), and Ni2+ (1mM) significantly decreased NDI, but Pb2+ at all concentra-tions treated didn't significantly decreased NDI. The results of MTT assay also showed that all of Cu2+, Mn2+, and Ni2+ at higher concentrations significantly decreased cell viability, but Pb2+ at lower concentration of 3μM significantly induced cytotoxicity. In addition, just only Pb2+ significantly increased Sb3+-induced cytotoxicity. Ca2+ at concentrations of 3mM and 10mM significantly antagonized the cytotoxicity of Mn2+ or Pb2+, respectively. Mg2+ at concentration of 3mM significantly reversed cytotoxicity of the four metals, but 10mM Mg2+ only reversed cytotoxicity of Cu2+ or Mn2+. The data of metal chelators study showed that 3μM D-PA significantly increased all of the four heavy metals induced cytotoxicity, but 30μM BAL significantly reduced Pb2+-induced cytotoxicity. The results of hypoploidy analysis showed that all of Cu2+, Mn2+, Ni2+ and Pb2+ didn't induce sub-G1 V79 cells, the results indicated all of the four metal ions didn't cause apoptosis in V79 cells. However, both Cu2+ and Ni2+ as adriamycin (positive control) caused G2/M phase block and increased population of V79 cells with higher granularity. Cell cycle distribution analysis further demonstrated that both Cu2+ and Ni2+ as adriamycin increased population of V79 cells in G2/M phase. There is only Mn2+ among the four metal ions as adriamycin markedly changed morphology of V79 lung cells. In addition, Mn2+ caused black precipitation, which might react with ingredients of medium or serum. These results showed that all of Cu2+, Mn2+, Ni2+ and Pb2+ induced cytogenotoxicities in V79 cells after two hours exposure. However, both Ca2+ and Mg2+ significantly decreased their cytogenotoxicity. Accordingly, we suggested that the mechanism of the four metals induced cytogenotoxicity might be partly related interfere with the biological functions of Mg2+ and Ca2+. In addition, BAL decreased Pb2+-induced cytotoxicity. Cytogenotoxic interactions between semiconductor metals were complication. Both Cu2+ and Ni2+ caused G2/M phase block. Mn2+ markedly changed morphology of V79 cells. These results showed that the four heavy metal ions induced cytogenotoxicities in V79 cells is in different properties.

This study explores the possibility of utilizing bioleaching techniques for nickel extraction from a mixed sulfide ore deposit with high magnesium content. Due to the ultramafic nature of this material, well-studied bioleaching technologies, which rely on acidophilic bacteria, will lead to undesirable processing conditions. This is the first work that incorporates nitrate-dependent bacteria under pH 6.5 environments for bioleaching of base metals. Experiments with both defined bacterial strains and indigenous mixed bacterial cultures were conducted with nitrate as the electron acceptor and sulfide minerals as electron donors in a series of microcosm studies. Nitrate consumption, sulfate production, and Ni released into the aqueous phase were used to track the extent of oxidative sulfide mineral dissolution; taxonomic identification of the mixed culture community was performed using 16S rRNA gene sequencing. Nitrate-dependent microcosms that contained indigenous sulfur- and/or iron-oxidizing microorganisms were cultured, characterized, and provided a proof-of-concept basis for further bioleaching studies.

碩士
中原大學
機械工程研究所
104
This study presents an analytic chip consisting of copper interdigital electrodes (Cu-IDE) and nickel-cobalt alloy nanowires (Ni-Co NWs) for the measurement of nitrate. Surface modification using 5-amino-1,3,4-thiadiazole-2-thio (ATT) was performed to promote the binding ability of Ni-Co NWs with NO_2^- by adding H_2 N functional group. Therefore, the electrical measurement through the Cu-IDE can provide stronger signal of the ionic bond of H_2 N functional group and NO_2^-, based on the principle of adsorption chromatography.In this study, nitrate crystal (measured in dry condition) and nitrate ion (measured in wet condition) were the experimental samples. Measurement result was the current-voltage response. The experimental results show that the lowest concentration of nitrate ion can be measured is 0.04 mM in wet condition. It is better than dry measurement of nitrate crystal with detection limit of 3 mM.

碩士
國立交通大學
電子物理系所
105
In this thesis, we report GaN nanowires (NWs) are directly synthesized on Si (111) through a home-made horizontal HVPE reactor at near-atmospheric pressure. The Si substrates were dipped in a 5% hydrofluoric acid (HF) solution for 10 minutes to remove native oxide. To assist the growth, the 10 nm nickel thin film was deposited on Si substrate as a catalyst using E-gun system. The precursor gas gallium chloride (GaCl) and high-purity ammonia gas are used as the reactant sources for Ga and N atom, respectively. The nitrogen (N2) and hydrogen (H2) were used as a carrier gas throughout the growth process. The structure and optical properties of GaN NWs investigated by XRD, SEM, TEM, and PL will be shown. We demonstrate the growth of GaN NWs on Si from nickel in HVPE. The growth takes place via VSS mechanism. The effects of V/III ratio, growth temperature and carrier gas flow rate are discussed, where all of them are critical in growing GaN NWs. The optimized growth parameters are suggested. The PL were measured at 10K for the NWs grown at different conditions. We propose the growth parameters where the single crystalline GaN NWs can be grown with nice morphology and good blue lighting emission. The control of NWs morphology and lighting property of GaN NWs opens up a pathway for future applications of small lighting transistors.

碩士
國立臺北科技大學
化學工程與生物科技系化學工程碩士班
107
Part I：In this study, a simple and environmentally friendly hydrothermal method was used to prepare a porous graphite carbonitride/manganese dioxide nanocomposite (GCN/MnO2), which was modified on a screen printed carbon electrode(SPCE), and for the first time applied to the electrochemical detection of nitrite, the rapid and sensitive detection efficiency of the nanocomposite electrode is helpful for the development of nitrite electrochemical detection. In this experiment, various physical and chemical techniques were used to detect properties: X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), N2 adsorption-desorption isotherm Field emission scanning electron microscopy (FE-SEM) and high-resolution field emission transmission electron microscopy (HR-TEM) were used to verify its morphology and structural properties, using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV), graphite nitride/manganese dioxide modified screen-printed carbon electrodes were studied for nitrite redox performance. In the study, GCN / MnO2 modified electrodes have high sensitivity (24.1777 μA μM-1 cm-2), low detection limit (1.23 nM), and a wide linear range (0.01–1520 μm), and in actual samples (rotation) In the detection of beef, tap water and water filter, it shows good electrocatalytic properties and good anti-interference properties, which means it has high practical value and can be applied to food safety related testing. Part II：In this study, a simple hydrothermal method was used to synthesize a nickel-nickel oxide/graphene oxide (NiS2 / GO) nanocomposite, and a glass probe was modified to further detect the toxic substance 4-hydroxynitrobenzene (4-HNB) in electrochemical sensing. In the experiment, the groups of the nanomaterials were first determined by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), and then the high-resolution field emission transmission electron microscope (HR-TEM) was used to laminate the nano composites. The appearance of the study; Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were also used to verify the electrochemical performance of nickel disulfide/graphene oxide modified glass probe (NiS2 / GO-GCE) with unmodified glassy carbon. Compared to the electrode (GCE), the sensor's sensing performance for 4-HNB is very significant, while the measured sensor has a wide linear range (0.1000-1053 μM) and a very low detection limit (59.5 nM). On the other hand, the detection of real river water samples also has a detection rate of more than 96%, which means that NiS2 / GO-GCE is very suitable for the detection of poisons in real water quality.

Nickel tetrakis(benzylmercapto)phthalocyanine (NiTBMPc) and nickel tetrakis(dodecylmercapto)phthalocyanine (NiTDMPc) complexes were synthesized and their spectral and electrochemical properties reported. The CV showed four or five redox processes for NiTBMPc and NiTDMPc, respectively. For the first time, spectroelectrochemistry gave evidence for the formation of Ni[superscript II]/Ni[superscrpt I] process in a NiPc complex. The rest of the processes were ring based. The NiTBMPc complex was successfully deposited on both gold and glassy carbon electrodes by electropolymerisation while NiTDMPc complex was deposited on gold electrode only. The films were electro-transformed in aqueous 0.1 M NaOH solution to the O–Ni–O oxo bridged form. The modified electrodes were characterized using electrochemical impedance spectroscopy and the results showed typical behavior for modified electrodes. Electrodes with poly-Ni(OH)Pcs films exhibited higher charge transfer resistance values, Rp than their corresponding poly-NiPcs films counterparts. All the modified electrodes showed improved catalytic activities than the unmodified electrodes towards nitrite ions electrooxidation. Better catalytic activities were observed for the modified electrodes when they were transformed to O–Ni–O oxo bridge form. All the modified electrodes exhibited high resistance to electrode surface passivation.

Nickel tetrakis(benzylmercapto)phthalocyanine (NiTBMPc) and nickel tetrakis(dodecylmercapto)phthalocyanine (NiTDMPc) complexes were synthesized and their spectral and electrochemical properties reported. The CV showed four or five redox processes for NiTBMPc and NiTDMPc, respectively. For the first time, spectroelectrochemistry gave evidence for the formation of NiII/NiI process in a NiPc complex. The rest of the processes were ring based. The NiTBMPc complex was successfully deposited on both gold and glassy carbon electrodes by electropolymerisation while NiTDMPc complex was deposited on gold electrode only. The films were electro-transformed in aqueous 0.1 M NaOH solution to the O–Ni–O oxo bridged form. The modified electrodes were characterized using electrochemical impedance spectroscopy and the results showed typical behavior for modified electrodes. Electrodes with poly-Ni(OH)Pcs films exhibited higher charge transfer resistance values, Rp than their corresponding poly-NiPcs films counterparts. All the modified electrodes showed improved catalytic activities than the unmodified electrodes towards nitrite ions electrooxidation. Better catalytic activities were observed for the modified electrodes when they were transformed to O–Ni–O oxo bridge form. All the modified electrodes exhibited high resistance to electrode surface passivation.

博士
國立臺北科技大學
機電科技研究所
100
This paper investigates the effects of adding a hexagonal boron nitride (h-BN) material on the material properties of the thermal sprayed Ni-Al coatings. The h-BN powder was mixed with the Ni-Al powder by blending or ball milling. They were sprayed on SUS304 substrate via plasma spray or high velocity oxygen fuel spray. WC-Co powder was also added into the coating to improve the hardness and the wear resistance. A DPV-2000 was used to monitor the temperature and velocity of the in-flight particles during spraying. Optical microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, porosity analysis, microhardness test, wear test and bond test were used to examine the properties of the coatings. The results show that the friction coefficient of the coating was reduced from 0.7 to 0.3 by adding h-BN. The high temperature and high pressure during spraying caused the molten or semi-molten droplets impinge harshly onto the substrate, resulting in the transformation from h-BN phase to an amorphous, turbostratic or cubic boron nitride phase. This transformation reflected on a better property of sliding wear resistance.

博士
國立成功大學
材料科學及工程學系碩博士班
94
In this study, the agglomeration behavior of gold thin films under annealing at low temperatures and the fundamental characteristics of sputtered nickel oxide films are investigated in order to apply these two　materials as the　contact of p-type gallium nitride. From recent studies about the formation of ohmic contact to p-type gallium nitride, there are many mechanisms expounded for the ohmicity. In order to probe the main factors which affect the contact ohmicity to p-type gallium nitride, the study was carried out by using four different approaches. 　　In approach 1, gold films of various thicknesses were sputtered on the p-type gallium nitride substrate. After annealing at 500 oC in oxygen ambient, the ohmicity can be achieved when the thickness of gold film is equal to or greater than 4 nanometers. However, the specific contact resistance is in the order of 10-1 Ω-cm2, which is too high for practical application. 　　In approach 2, the samples were annealed in various ambients. It is concluded that the oxygen annealing ambient is more helpful to form the ohmic characteristics as compared to the nitrogen ambient. 　　In approach 3, the gold morphology in the contact was intentionally modified. The ohmic characteristics can be obtained when gold presents the morphology of three-dimensional network structure in the contact after annealing at 400 oC in nitrogen ambient. And, the specific contact resistance is in the order of 10-3 Ω-cm2. 　　In approach 4, the microstructure of contact/substrate interface was varied. The specific contact resistance is as low as the grade of 10-4 Ω-cm2 when the microstucture shows the triple-phase junction structure of “Au-NiO-p-GaN”after annealing at 400 oC in oxygen ambient. 　　Finally, the mechanism for the formation of ohmic contact to p-type gallium nitride is discussed, based on the integration of experimental results of the four approaches.

博士
國立成功大學
微電子工程研究所碩博士班
99
The fabrication of GaN-based Schottky barrier PDs on patterned sapphire substrate (PSS) was investigated. The stripe width and spacing of PSS template were both 3 μm. The depth of the groove was controlled at 150 nm by ICP etching. A high quality GaN Schottky barrier PD was prepared on PSS by metalorganic chemical vapor deposition (MOCVD). Comparing with the PD prepared on conventional flat sapphire substrate (FSS), it was found that we can reduce dark current and enhance responsivity. Furthermore, it was found that full-width-half-maxima (FWHMs) measured the samples prepared on from FSS and PSS were 255 and 186 arcsec, respectively. The significantly smaller FWHM observed from the sample prepared on PSS again be attributed to the smaller TD density. We also determine Schottky barrier height (ΦBE) and ideality factor (n) from the forward I-V characteristics, it was found that ΦBE and n for the PD prepared on FSS were 0.69eV and 1.82, respectively, while ΦBE and n for the PD prepared on PSS were 0.79eV and 1.53, respectively. The larger turn-on voltage, the larger ΦBE and smaller n observed from the PD prepared on PSS should again be attributed to the reduced TD density. Under -2 V applied bias, it was found that noise equivalent power (NEP) and normalized detectivity (D*) were 9.08×10-11 W and 1.74×1010 cmHz0.5W-1, respectively, for the PD prepared on PSS. These values were also better than those achieved from the PD prepared on flat sapphire substrate. Besides PSS approach, we report the preparation of nanorod (NRs) templates with a simplified NRELOG method and the fabrication of GaN Schottky barrier PDs on the nanorod template. In this thesis, GaN nanorods were vertically aligned with an average diameter of 350 nm. It was also found that density of the GaN nanorods was around 3×108 cm-2. Comparing with conventional substrate, it was found that FWHMs measured from NR_PD and PD were 422 and 525 arcsec, respectively. In dark current and rejection contrast, the significant three orders of magnitude and 350 times are reduction in reverse leakage current and responsivity observed from NR_PD, respectively. With -2 V applied bias, it was found that noise equivalent power (NEP) and normalized detectivity (D*) were 7.00×10-10 W and 2.26×109 cmHz0.5W-1, respectively, for the PD prepared on nanorods template. With the same -2 V bias, it was found that NEP and D* were 3.56×10-6 W and 4.44×105 cmHz0.5W-1, respectively, for the PD prepared on a conventional sapphire substrate. Finally, we reveal a new method to improve the performance of PDs that use Ni treatment. In first stage, we deposited Ni catalytic films with different thicknesses onto the as-grown Mg-doped GaN epitaxial layers and subsequently annealed the samples by conventional furnace annealing. It was found that surface of the Ni catalytic films became rough with numerous island structures after thermal treatment. With a 10 nm-thick Ni film, it was found that we achieved a hole concentration of 4.35×1017 cm?3 with a 400 ℃ annealing. Without the Ni catalytic film, we could achieve p-type conduction only when the annealing temperature was equal to or larger than 600 ℃. SIMS results show that H concentration was reduced and a certain amount of Ni atoms seem to penetrate into the GaN epitaxial layers after annealing. Furthermore, it was found that we could only achieve p-GaN with high hole concentration at the sample surface by using the Ni catalytic films. On the contrary, we first try to use this methodology to improve GaN-based PD performance. It was found that ΦBE and n for the PD prepared on Ni treatment sample were 1.008 eV and 1.263, respectively, while ΦBE and n for the PD prepared on as-grown sample were 0.698 eV and 1.822, respectively, at 600 ℃, O2 ambient. It was found that we can reduce dark current and enhance responsivity, too. The rejection contrast is raised from 104 (without Ni treatment) to 12149 (with Ni treatment at 600 ℃). It can be seen clearly that NEP increased while D* decreased monotonically with the increase of applied reverse bias. With -2 V applied bias, it was found that NEP for the PDs prepared without and with Ni treatment were 9.95×10-8 and 1.74×10-11 W, respectively. At the same applied bias, it was found that D* for PDs prepared without and with Ni treatment were 1.57×107 and 9.07×1010 cmHz0.5W-1, respectively. The smaller NEP and higher D* observed from the PD prepared with Ni treatment indicate we can also improve noise characteristics of GaN-based UV PDs by using Ni treatment methodology.

Global warming and depletion in fossil fuels have forced the society to search for alternate, clean sustainable energy sources. An obvious solution to the aforesaid problem lies in electrochemical energy storage systems like fuel cells and batteries. The desirable properties attributed to these devices like quick response, long life cycle, high round trip efficiency, clean source, low maintenance etc. have made them very attractive as energy storage devices. Compared to many advanced battery chemistries like nickel-metal hydride and lithium - ion batteries, metal-air batteries show several advantages like high energy density, ease of operation etc. The notable characteristics of metal - air batteries are the open structure with oxygen gas accessed from ambient air in the cathode compartment. These batteries rely on oxygen reduction and oxygen evolution reactions during discharging and charging processes. The efficiency of these systems is determined by the kinetics of oxygen reduction reaction. Platinum is the most preferred catalyst for many electrochemical reactions. However, high cost and stability issues restrict the use of Pt and hence there is quest for the development of stable, durable and active electrocatalysts for various redox reactions. The present thesis is directed towards exploring the electrocatalytic aspects of titanium carbonitride. TiCN, a fascinating material, possesses many favorable properties such as extreme hardness, high melting point, good thermal and electrical conductivity. Its metal-like conductivity and extreme corrosion resistance prompted us to use this material for various electrochemical studies. The work function as well as the bonding in the material can be tuned by varying the composition of carbon and nitrogen in the crystal lattice. The current study explores the versatility of TiCN as electrocatalyst in aqueous and non-aqueous media. One dimensional TiC0.7N0.3 nanowires are prepared by simple one step solvothermal method without use of any template and are characterized using various physicochemical techniques. The 1D nanostructures are of several µm size length and 40 ± 15 nm diameter (figure 1). Orientation followed by attachment of the primary particles results in the growth along a particular plane (figure 2). (a) (b) (c) Figure 1. (a) SEM images of TiC0.7N0.3 nanowires (b) TEM image and (c) High resolution TEM image showing the lattice fringes. (a) (b) (d) Figure 2. Bright field TEM images obtained at different time scales of reaction. (a) 0 h; (b) 12 h; (c) 72 h and (d) 144 h. The next aspect of the thesis discusses the electrochemical performance of TiC0.7N0.3 especially for oxygen reduction. Electrochemical oxygen reduction reaction (ORR) reveals that the nanowires possess high activity for ORR and involves four electron process leading to water as the product. The catalyst effectively converts oxygen to water with an efficiency of 85%. A comparison of the activity of different (C/N) compositions of TiCN is shown in figure 3. The composition TiC0.7N0.3 shows the maximum activity for the reaction. The catalyst is also very selective for ORR in presence of methanol and thus cross-over issue in fuel cells can be effectively addressed. Density functional theory (DFT) calculations also lead to the same composition as the best for electrocatalysis, supporting the experimental observations. Figure 3. Linear sweep voltammetric curves observed for different compositions of titanium carbonitride towards ORR. The next chapter deals with the use of TiC0.7N0.3 as air cathode for aqueous metal - air batteries. The batteries show remarkable performance in the gel- and in liquid- based electrolytes for zinc - air and magnesium - air batteries. A partial potassium salt of polyacrylic acid (PAAK) is used as the polymer to form a gel electrolyte. The cell is found to perform very well even at very high current densities in the gel electrolyte (figures 4 and 5). Figure 4 Photographs of different components of the gel - based zinc - air battery. (a) (b) Figure 5. a) Discharge curves at different current densities of 5, 20, 50 and 100 mA/cm2 for zinc-air system with TiC0.7N0.3 cathode b) Charge – discharge cycles at 50 mA/cm2 for the three electrode configuration with TiC0.7N0.3 nanowire for ORR and IrO2 for OER and Zn electrode (2h. cycle period). Similarly, the catalytic activity of TiC0.7N0.3 has also been explored in non-aqueous electrolyte. The material acts as a bifunctional catalyst for oxygen in non- aqueous medium as well. It shows a stable performance for more than 100 cycles with high reversibility for ORR and OER (figure 6). Li-O2 battery fabricated with a non-aqueous gel- based electrolyte yields very good output. (a) (b) (c) Figure 6. Galvanostatic charge –discharge cycles. (a) at 1 mA/cm2 (b) specific capacity as a function of no. of cycles (c) photographs of PAN-based gel polymer electrolyte. Another reaction of interest in non –aqueous medium is I-/I3-. redox couple. TiC0.7N0.3 nanowires show small peak to peak separation, low charge transfer resistance and hence high activity. The catalyst is used as a counter electrode in dye sensitized a solar cell that shows efficiencies similar to that of Pt, state of the art catalyst (figure 7). (a) (b) (c) Figure 7 (a) Cyclic voltammograms for I-/I3 - redox species on TiC0.7N0.3 nanowires (red), TiC0.7N0.3 particle (black) and Pt (blue). (b) Photocurrent density - voltage characteristics for DSSCs with different counter electrodes. TiC0.7N0.3 nanowire (black), TiC0.7N0.3 particle (blue), Pt (red). (c) Photograph of a sample cell. (a) (b) (c) (d) Figure 8 a) Comparison ORR activity for (i) NiTiO3(black), (ii) N-rGO (red), (iii) NiTiO3 – N-rGO (green) and (iv) Pt/C (blue) (b) Linear sweep voltammograms for OER observed on NiTiO3 – N-rGO composite (black), NiTiO3 (brown), N-rGO (blue), glassy carbon (red) in 0.5 M KOH. (c) Galvanostatic discharge curves of NiTiO3 – N-rGO as air electrode (d) Charge – discharge cycle at 5 mA/cm2 for the rechargeable battery with 10 min. cycle period. The last part of the thesis discusses about a ceramic oxide, nickel titanate. The electrocatalytic studies of the material towards ORR and OER reveal that the catalyst shows remarkable performance as a bifunctional electrode. A gel - based zinc - air battery fabricated with nickel titanate – reduced graphene oxide composite shows exceptional performance of 1000 charge-discharge cycles in the rechargeable mode (figure 8). Of course, the primary battery configuration works very well too The thesis contains seven chapters on the aspects mentioned above with summary and future perspectives given as the last chapter. An appendix based on TiN nanotubes and supercapacitor studies is given at the end.