Дисертації з теми "Cobalt ferrite thin film"
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Spillane, Liam Jonathan. "Nanoanalytical electron microscopy of cobalt ferrite thin films." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/6447.
Повний текст джерелаRamos, Ana V. "Epitaxial Cobalt-Ferrite Thin Films for Room Temperature Spin Filtering." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2008. http://tel.archives-ouvertes.fr/tel-00394398.
Повний текст джерелаStichauer, Libor. "Étude des propriétés optiques et magnéto-optiques de films nanocristallins de ferrite de cobalt." Nancy 1, 1994. http://www.theses.fr/1994NAN10365.
Повний текст джерелаMartin, Élodie. "Modulation de l'anisotropie dans le ferrite de cobalt en couches minces pour des applications en électronique de spin." Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAE026/document.
Повний текст джерелаThe field of magnetic storage is in constant progress to constantly push further the storage capacity of the device. A promising approach is the perpendicular magnetic recording of datas. The material presented in this manuscript is cobalt ferrite. It is an excellent candidate for the realization of perpendicular storage device due to its properties. The present work deals with the modification of the magnetic anisotropy by doping the ferrite cobalt thin films with rare earth elements. We have demonstrated the possibility to modulate the easy magnetization axis of undoped cobalt ferrite by changing the partial pressure of O2/N2 during the elaboration of the thin films. We have also highlighted the insertion of rare earth elements into the structure of the cobalt ferrite although their important ionic radii. The impact of the rare earth anisotropy on the magnetic properties of the ferrite cobalt has also been observed
Mukherjee, Devajyoti. "Growth and Characterization of Epitaxial Thin Films and Multiferroic Heterostructures of Ferromagnetic and Ferroelectric Materials." Scholar Commons, 2010. http://scholarcommons.usf.edu/etd/3622.
Повний текст джерелаRoos, Andreas. "Growth and characterization of advanced layered thin film structures : Amorphous SmCo thin film alloys." Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-177674.
Повний текст джерелаSrinivasan, Durgam Rangaswamy. "The structure and properties of cobalt -nickel thin film magnetic recording tapes." Thesis, Brunel University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.255841.
Повний текст джерелаAmiri-Hezaveh, A. "Photelectron spectroscopy of ultra-thin epitaxial f.c.c. magnetic films of iron and cobalt." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233668.
Повний текст джерелаTakano, Kentaro. "Exchange anisotropy in thin film bilayers of nickel cobalt monoxide and various ferromagnetic materials /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC IP addresses, 1998. http://wwwlib.umi.com/cr/ucsd/fullcit?p9820884.
Повний текст джерелаKretzschmar, B. S. M., K. Assim, Andrea Preuß, A. Heft, Marcus Korb, Marc Pügner, Thomas Lampke, B. Grünler, and Heinrich Lang. "Cobalt and manganese carboxylates for metal oxide thin film deposition by applying the atmospheric pressure combustion chemical vapour deposition process." Technische Universität Chemnitz, 2018. https://monarch.qucosa.de/id/qucosa%3A21422.
Повний текст джерелаKenny, Leo Thomas. "Preparation and characterization of lithium cobalt oxide by chemical vapor deposition for application in thin film battery and electrochromic devices /." Thesis, Connect to Dissertations & Theses @ Tufts University, 1996.
Знайти повний текст джерелаAdviser: Terry E. Haas. Submitted to the Dept. of Chemistry. Includes bibliographical references. Access restricted to members of the Tufts University community. Also available via the World Wide Web;
Nallan, Himamshu, Thong Ngo, Agham Posadas, Alexander Demkov, and John Ekerdt. "Area Selective Deposition of Ultrathin Magnetic Cobalt Films via Atomic Layer Deposition." Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-207142.
Повний текст джерелаMattarello, Valentina. "Au-Co Thin Films and Nanostructures for MagnetoPlasmonics." Doctoral thesis, Università degli studi di Padova, 2016. http://hdl.handle.net/11577/3421781.
Повний текст джерелаIl presente lavoro si inserisce nell'ambito della scienza e ingegneria dei materiali per la MagnetoPlasmonica. Questa ultima è una recente, ma allo stesso tempo crescente, area di ricerca che mira a combinare le proprietà plasmoniche tipiche dei metalli nobili nanostrutturati (quali, ad esempio, l’intensificazione del campo elettromagnetico locale o la trasmissione ottica straordinaria) con funzionalità di tipo magnetico. Promettenti applicazioni spaziano dalla sensoristica alla realizzazione di nanocircuiti totalmente ottici, solo per citarne alcuni. Tradizionalmente i sistemi per MagnetoPlasmonica più considerati in letteratura prevedono l’accoppiamento di un film sottile o arrangiamento nanostrutturato di metalli nobili con materiale ferromagnetico. Tuttavia, al fine di migliorare le prestazioni di suddetti sistemi e/o esplorare nuove funzionalità è necessario ricercare nuovi composti in cui già il materiale innovativo presenta proprietà plasmoniche e magnetiche. Scopo della presente tesi è la realizzazione e lo studio di film sottili e nanostrutture a base di lega Au-Co: l’oro è, infatti, un metallo nobile tra i migliori per applicazioni in plasmonica e il cobalto è un materiale ferromagnetico. I due metalli allo stato bulk sono notoriamente immiscibili. Con la tecnica di deposizione magnetron sputtering sono stati depositati (in geometria di codeposizione) film sottili Au:Co, caratterizzati da tre diverse composizioni, ovvero Au2Co1, Au1Co1 e Au1Co2 e tre diversi spessori, rispettivamente ≈ 15 nm, ≈ 30 nm e ≈ 100 nm. Una ricerca estesa è stata condotta con l’obiettivo di studiare attentamente le proprietà strutturali dei film, combinando diffrazione a raggi X, con misure di Assorbimento X svolte al Sincrotrone e Microscopia elettronica. I risultati dimostrano che la parte predominante del film è costituita da una lega Au-Co che è tipicamente più ricca in oro rispetto ai rapporti atomici nominali di Au e Co. La frazione di lega, la sua stechiometria e l’ordine locale dipendono dal rapporto Au/Co inizialmente presente. Inoltre, mentre nel campione Au2Co1 la lega è prevalentemente amorfa, nel caso delle leghe più ricche in cobalto vi è la presenza di grani FCC cristallini, allungati lungo la direzione di crescita del film, fortemente tessiturati (in cui i piani (111) sono prevalentemente paralleli al substrato) e caratterizzati da un parametro reticolare che diminuisce all'aumentare del contenuto di cobalto. Oltre alla fase di lega, sono presenti dei clusters di cobalto, caratterizzati da un basso ordine strutturale. L’interfaccia tra due fasi magnetiche è stata confermata da misure SQUID che hanno inoltre permesso di caratterizzare i cicli di isteresi dei film Au:Co e di stimarne i valori di magnetizzazione di saturazione. Le proprietà ottiche dei film sono state caratterizzate con misure di trasmittanza (nel range UV-Vis) ed Ellissometria. Da un punto di vista termico, la lega Au-Co si dimostra stabile fino a 200° C; al crescere della temperatura ha lungo una de-alligazione che porta alla formazione di fasi metalliche separate di oro e cobalto. I materiali Au-Co così preparati e caratterizzati sono stati poi impiegati come componente metallica in array periodici nanostrutturati, i.e., Semi Nano-Shell Array e Nano Hole Array. Gli array sono stati caratterizzati da un punto di vista morfologico e ottico dimostrandosi promettenti piattaforme per future caratterizzazioni MagnetoPlasmoniche.
Chung, Jae-Young. "Broadband Characterization Techniques for RF Materials and Engineered Composites." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1269542888.
Повний текст джерелаPERRIN, GERALDINE. "Elaboration par pvd et caracterisation de couches minces ferromagnetiques sur film souple pour des applications hyperfrequence." Université Joseph Fourier (Grenoble), 1996. http://www.theses.fr/1996GRE10199.
Повний текст джерелаŠimíková, Michaela. "Selektivní růst kovových materiálů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228773.
Повний текст джерелаBarolo, Andrea. "Studio di catalizzatori a base di film sottili di ossidi metallici di transizione su substrato metallico monocristallino." Doctoral thesis, Università degli studi di Padova, 2011. http://hdl.handle.net/11577/3427523.
Повний текст джерелаQuesto lavoro discute in proposito di film sottili di ossidi di metalli di transizione su substrato metallico cristallino in riferimento alla loro morfologia e reattività verso i gas. In particolare i sistemi analizzati sono CoO su Pd(100), SnO su Pt(110) and NiO su Pd(100).
Slimi, Houyem. "Élaboration et caractérisation de couches minces co-dopées In, Co, préparées par la pulvérisation cathodique, applications aux cellules photovoltaïques." Thesis, Littoral, 2019. http://www.theses.fr/2019DUNK0533/document.
Повний текст джерелаThis work has a purpose to make thin layers of Zno co-dopees cobalt and indium for the production of photovoltaic cells. For the manufacture of thin layers, we have chosen the method of magnatron sputtring. This method allows we obtain layers having different properties which depend on parameters of deposition. Thick layers of cizo obtained are received inN2 and H2 for series 1 and O2 for series 2. In the first part of this work, we have undertaken a study of the morphological, vibrational and optical properties. In the second part of this work, we have experienced the effect of thickness and the effect of anneling on the different properties (structural, morphological, optical, and electrical) of our samples. In the third part of this work, we have investigated the influence of annealing time on the different properties (structural, morphological, optical and electrical) of our samples
Badoz, Pierre-Antoine. "Propriétés de transport électronique dans les hétérostructures métal/semiconducteur." Grenoble 1, 1988. http://www.theses.fr/1988GRE10024.
Повний текст джерелаDinh, Thi Mong Cam. "Influence des conditions d'élaboration sur les transformations de phases dans les couches minces de cobaltites de fer à structure spinelle." Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30090.
Повний текст джерелаThin spinel films of Co1.7Fe1.3O4 iron cobaltites, whose composition is in the miscibility gap of the CoFe2O4-Co3O4 phase diagram, were prepared by RF sputtering near room temperature. The films obtained, whose thicknesses were fixed at 300 nm, consist of crystallites with a mean diameter close to 20 nm. The treatment of these samples at 600 °C for several hours leads to the formation of two spinel phases, in agreement with the phase diagram. This transformation was clearly established, both by X-ray diffraction and Raman spectroscopy. In "bulk" iron cobaltites of close or same compositions, such a transformation is of spinodal type and is characterized by a pseudo-periodic organization of rich iron and cobalt-rich spinel phases on a scale of a few tens of nanometers. In order to highlight this organization in the thin films, microscopy studies were carried out. A specific preparation process was even developed in order to cut in-plane thin sections, by the focused ion beam (FIB) technique. Crystallites can thus be observed and studied individually. The analyzes revealed, however, and in the best case (i.e. for the largest crystallites), the presence of only two zones of different compositions. The expected pseudo-periodic alternation could never be observed. It seems that the nanometric size of the crystallites, prevents the spinodal transformation which was highlighted in the "bulk" samples. The observation of local chemical anomalies in grain boundaries corroborates this hypothesis, which suggests a "nano" effect on phase transformation. For the present work, it was furthermore found that in addition to the temperature and the annealing time, the sputtering conditions also have a significant impact on the formation and decomposition of the phases in the thin films. Although this study did not find the deposition conditions that lead directly to the formation of two spinel phases after sputtering, it shows however that certain conditions shorten the annealing times while lowering the temperatures required to perform the targeted transformation. For the first time, iron cobaltite thin films were subjected to laser beam treatments to induce phase transformations within them. It was shown that the formation of two spinels from a single-phase film can be achieved in very short times and at low laser power, probably because of a rapid and high rise of local temperature, due to the absorption of the laser beam. The numerous parameters offered by the photolithography machine used (power, scanning speed, scanning increment, focusing, etc.) could not be exhaustively explored during this study. The latter should therefore be considered only as a preliminary work. The results, however, are promising and seem to bring out a new treatment route, allowing simple phase transformations in iron cobaltites
Benamara, Omar. "Croissance physique d'îlots de Pt et Co sur oxydes pour l'auto-organisation de nano-bâtonnets de Co élaborés par synthèse chimique." Thesis, Toulouse, INSA, 2010. http://www.theses.fr/2010ISAT0032/document.
Повний текст джерелаThe subject of this thesis is to be part of strategies in order to organize nanostructures, particularly strategies to increase information density in magnetic media. The synthesis techniques used in chemistry (LPCNO-INSA laboratory) is allowed to develop monocrystalline nanorods of cobalt whose ferromagnetic properties in terms of anisotropy and magnetization present a great interest for applications in the field of magnetic storage. The success in controling the growth of these nanorods arranged perpendicularly on a substrate can lead to achieve a high density media. We tested the perpendicular growth of monocrystalline nanorods of cobalt on a continuous and epitaxial layer of Pt (111) grown on a substrate of sapphire (Al2O3) and showed that this combination of two types of deposits (physical and chemical) give actually a dense and perpendicular network of Co nanorods. In the aim to organizing this growth and decoupling physically the nanorods we studied the growth of these Co nanorods on 3D metallic islands of Pt and Co. In the first part we studied the crystal structure, morphology, size distributions and the stress state of Pt and Co islands deposited on the surface (0001) of sapphire and (001) surface of MgO by sputtering. And in the second part, we studied the growth of Co nanorods on a Pt and Co islands mastered in the previous step
Jouaiti, Abdelaziz. "Activation electrochimique de petites molecules par des composes bi-metalliques et elaboration de films polymeres conducteurs." Université Louis Pasteur (Strasbourg) (1971-2008), 1989. http://www.theses.fr/1989STR13036.
Повний текст джерелаLenoble, Marie-Anne. "Dépot électrolytique de CoFeCu, matériau magnétique doux de forte induction pour tetes magnétiques." Grenoble INPG, 1995. http://www.theses.fr/1995INPG0156.
Повний текст джерелаSangeneni, Neelima. "Microwave synthesis of superparamagnetic cobalt-ferrite thin films for RF CMOS applications." Thesis, 2018. https://etd.iisc.ac.in/handle/2005/4885.
Повний текст джерелаRodewald, Jari Michael. "Advancement of growth and characteristics of ultrathin ferrite films." Doctoral thesis, 2021. https://repositorium.ub.uni-osnabrueck.de/handle/urn:nbn:de:gbv:700-202102124037.
Повний текст джерелаRoy, Debangsu. "Exchange Spring Behaviour in Magnetic Oxides." Thesis, 2012. http://etd.iisc.ac.in/handle/2005/3172.
Повний текст джерелаRoy, Debangsu. "Exchange Spring Behaviour in Magnetic Oxides." Thesis, 2012. http://hdl.handle.net/2005/3172.
Повний текст джерелаLan, Kai Wei, and 藍凱威. "Cobalt Tungsten Oxide Target Fabrication and Thin Film Deposition." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/s2e73p.
Повний текст джерелаHsu, Jing-Chang, and 許晉章. "The Fabrication and Characteristics Investigation of Bismuth Ferrite Thin Film by Sputtering." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/t2s496.
Повний текст джерела國立臺灣大學
機械工程學研究所
107
In this thesis, we use radio frequency magnetron sputtering deposition technique to fabricate a multiferroic material, Bismuth ferrite(BFO), which possesses ferroelectric and anti-ferromagnetic property in the same time. We deposit BFO samples at the same temperature but anneal them at different temperature and in different atmosphere to find if there are some differences in crystal structure and electric properties. Then we choose the best of all to integrate with Barium titanate into a bilayer thin film. The combination of BTO and BFO is to learn the magneto-electric effect between ferroelectric and anti-ferromagnetic materials. In addition, we fabricate 5 different thickness ratio of the BTO/BFO bilayer to find out at which ratio will the best electric characteristic occur. According to results, the performance of Bismuth ferrite single layers is not good, the leakage current is about 10-1~10-2 ampere, the P-E loops look like a oval ball because of poor dielectric property, and worst of all, we cannot even measure the capacitance property. But everything changes in BTO/BFO bilayer structures due to the interlayer coupling effect. First, the leakage current plummets to 10-6~10-7 ampere. Second, the capacitance becomes measureable and the value is about 6x10-9 farad. Third, the maximum polarization is up to 4 μC/cm2. It’s a tremendous progress from BFO single layer to BTO/BFO bilayer. What disappoints us is that the magneto-electric measurements show that the applied magnetic field has no effect on our samples.
"Preparation and characterization of granular magnetic cobalt silver thin film." 2000. http://library.cuhk.edu.hk/record=b5890295.
Повний текст джерелаThesis submitted in: September 1999.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2000.
Includes bibliographical references (leaves 94-97).
Abstracts in English and Chinese.
Acknowledgements --- p.2
Abstract --- p.3
Table of Contents --- p.5
List of Figures --- p.7
List of Tables --- p.13
Chapter Chapter 1 --- Introduction --- p.14
Chapter 1.1. --- Overview --- p.14
Chapter 1.2. --- Giant Magnetoresistance (GMR) --- p.15
Chapter 1.3. --- Application of GMR Materials --- p.20
Chapter 1.4. --- Preparation Methods --- p.22
Chapter 1.5. --- This Thesis --- p.23
Chapter Chapter 2 --- Sample Preparation and Experimental Methods --- p.24
Chapter 2.1. --- MEVVA Ion Source Implanter --- p.24
Chapter 2.2. --- The Pulsed Filtered Cathodic Arc Co-deposition System --- p.26
Chapter 2.3. --- Sample Preparation --- p.29
Chapter 2.3.1 --- Implantation Condition --- p.29
Chapter 2.3.2 --- Co-deposition Conditions --- p.31
Chapter 2.4. --- Characterization methods --- p.32
Chapter 2.4.1 --- Magnetoresistance Measurement --- p.32
Chapter 2.4.2 --- Atomic Force Microscopy and Magnetic Force Microscopy --- p.34
Chapter 2.4.3 --- Rutherford Backscattering Spectroscopy (RBS) --- p.37
Chapter 2.4.4 --- SQUID Magnetometer --- p.38
Chapter Chapter 3 --- Characterization of Implanted Samples --- p.39
Chapter 3.1. --- Introduction --- p.39
Chapter 3.2. --- Results and Discussion --- p.39
Chapter 3.2.1 --- Ag Film Thickness Dependence --- p.39
Chapter 3.2.2 --- Dose Dependence --- p.44
Chapter 3.2.3 --- Extraction Voltage Dependence --- p.46
Chapter 3.2.4 --- Annealing Temperature Dependence --- p.49
Chapter 3.2.5 --- Thicker Layer Formation --- p.56
Chapter 3.2.6 --- AFM and MFM Measurements --- p.58
Chapter 3.3. --- Summary --- p.64
Chapter Chapter 4 --- Characterization of Co-deposited Samples --- p.65
Chapter 4.1. --- Introduction --- p.65
Chapter 4.2. --- Results and discussion --- p.65
Chapter 4.2.1 --- RBS Measurement --- p.65
Chapter 4.2.2 --- Magnetoresistance Measurement --- p.66
Chapter 4.2.3 --- AFM Measurement --- p.69
Chapter 4.2.4 --- MFM Measurement --- p.76
Chapter 4.3. --- Summary --- p.84
Chapter Chapter 5 --- Conclusion --- p.85
Chapter 5.1. --- Main Results of This Work --- p.85
Chapter 5.2. --- Suggestions on Future Works --- p.87
Appendix --- p.89
Reference --- p.94
Publications --- p.97
Liu, Wen-Tsang, and 劉文燦. "The Synthesis and Mechanism of Barium Ferrite Thin Film by Sol-Gel Method." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/93037361884733699901.
Повний текст джерелаYang, Chang-Ying, and 楊長穎. "Large area graphene – cobalt manganese oxide thin film for oxygen evolution reaction." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/14084524668459287138.
Повний текст джерела國立中山大學
化學系研究所
104
It is necessary to develop clean and green energy because of the shortage of non-renewable energy. The hydrogen and oxygen generated by water splitting is one of the solution for clean energy. However, energy required for water splitting is usually greater than energy generated by water splitting. Oxygen evolution reaction (OER) is the main reason of excessive energy consumption in the splitting process, thus it is necessary to prepare a catalyst to promote the OER. In this research, by a simple redox method with heating, we successfully synthesized cobalt manganese oxide hydroxide (CMOH) catalyst. This method is fast and simple; efficiently deposit catalytic thin film on large area substrate even on complex surfaces. At first, we used cobalt sulfate as precursor to prepare catalytic films (CMOH-sulfate, CMOH-S) for electrochemical measurement. However, the films (CMOH-acetate, CMOH-A) prepared by cobalt acetate have superior optical properties to CMOH-S, so we chose cobalt acetate for subsequent experiments. To further understand the difference between CMOH-S and CMOH-A, We characterized these two thin film by a series of characterization. The results of UV-visible and AFM show that the thickness of CMOH-A is smaller than CMOH-S thus has higher transmittance. CMOH-A have transmittance of 87.15% with thickness of 60 nm versus CMOH-S having 60.39% transmittance and 120 nm thickness. We further confirmed the thickness of CMOH-A to be 5 to 10 nm by TEM (rather than 60 nm by AFM), and the composition is amorphous. Despite the difference on optical property, CMOH-S and CMOH-A exhibit almost the same on OER activity. To study the reason, we altered the length of CMOH-A films, knowing that the active sites actually lie at the interface of catalyst and FTO glass. Finally, after covering a layer of graphene on the catalytic thin films and go through 500ºC calcination under Ar, we tremendously raise the stability of OER catalyzing process, with only 7.6% decay of current after 3000 circles scanning and still remain at same over potential (0.47 V at 10 mA cm-2).
Lin, Bo-Lu, and 林栢祿. "Diffusion barrier characteristics of TaN thin film on cobalt cemented tungsten carbide." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/66234581999559070656.
Повний текст джерела國立臺灣海洋大學
材料工程研究所
98
To prevent the diffusion out of cobalt from cemented tungsten carbides at high working temperature, TaNx coatings were prepared as a diffusion barrier by direct current magnetron sputtering using a Ta target in an argon-nitrogen atmosphere. The nitrogen flow ratio, N2/(N2+Ar), in the sputtering process varied from 0.05 to 0.4. The deposition rate reduced as the nitrogen flow ratio increased. Silicon wafers and 6wt% cobalt cemented tungsten carbide were used as the substrates. Effects of nitrogen flow ratio on crystalline characteristics and mechanical properties of the TaNx coatings were examined by X-ray diffraction. The TaNx coatings were annealed at 500, 600, 700, and 800oC for 4 hours in air, respectively. The diffusion barrier performance was evaluated by Auger electron spectroscopy depth profiles and X-ray diffraction. Oxidation resistance of the TaNx coatings was also investigated. Orthorhombic Ta2O5 was observed after annealing above 600oC. If the 6wt% cobalt cemented tungsten carbide was used as the substrates, the WO3 oxide compound was found when the annealing temperature was over 600 oC in air. When the oxide appeared, the thin film surface become more rougher. The TaNx deposited on cemented tungsten carbides played the role of diffusion barrier for Co at 600oC for 4 hours in air. But the diffusion barrier was not effective under high temperature in air due to the oxidation problem, which was transferred from TaN to Ta2O5. If the diffusion barrier was used under low vacuum environment, such as, at 600 oC for 4 hours, the TaNx coating should be successful to play the role of diffusion barrier for Co diffusion.
Lin, Yu-Ting, and 林育廷. "Diffusion barrier characteristics of CrTaN thin film on cobalt cemented tungsten carbide." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/16377992891784606267.
Повний текст джерела國立臺灣海洋大學
材料工程研究所
99
To prevent the diffusion out of cobalt from cemented tungsten carbides at high working temperatures, CrTaN coating were prepared as a diffusion barrier by reactive direct current magnetron co-sputtering onto 6 wt.% cobalt cemented tungsten carbide substrates, using Ta and Cr targets in an argon-nitrogen atmosphere. The nitrogen flow ratio, N2/(Ar+N2), during the sputtering process was set at 0.4. The deposition rates of CrTaN coatings varied from 23 to 27 nm/min. The CrTaN coatings crystallized into a columnar structure, without heating the substrates during the sputtering process and exhibited surface hardness and Young's modulus values of 16–27 and 211–383 GPa, respectively. The annealing treatments were conducted at 500 and 600oC for 4 hours in air and 600oC for 4 hours in 50 ppm oxygen with balanced nitrogen gas. The diffusion barrier performance was evaluated by Auger electron spectroscopy depth profiles (AES), and X-ray diffraction (XRD). Oxidation resistance of the CrTaN coatings was also investigated. Orthorhombic L-Ta2O5 and rhombohedral Cr2O3 was observed after annealing at 500 and 600oC for 4 hours in air. When the oxide appeared, the thin film surface become more rough, the surface hardness and Young's modulus values decreased. Annealing in 600oC for 4 hours in a 50 ppm O2-N2 atmosphere, surface not oxide phase was observed. The hardness and Young's modulus values was increased. We also investigated oxidation resistance of the CrTaN coatings under a 50 ppm O2-N2 atmosphere, to assess the fabricated layers effectiveness as a protective coating for glass molding dies. Next carbon nitride films were deposited on the CrTaN films, to increase the surface wear property, because carbon nitride film has a batter wear resistance. The films were annealing in 50 ppm O2-N2 environment to simulate the glass molding environment, to observe the adhesion of CrTaN, surface roughness and hardness.
Wu, Kuan-Chen, and 吳冠辰. "Effect of cobalt on barrier properties of electroplating RuCo alloy thin film." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/6zsg8a.
Повний текст джерелаShih, Ming-Chi, and 施銘奇. "Synthesis of Multiple Metal Oxide Thin Film and Discontinuous Cobalt and Manganese Oxide Thin Film to Enhance Electrocatalytic Oxygen Evolution Reaction." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/zh8w5d.
Повний текст джерела國立中山大學
化學系研究所
107
Electrolysis of water is an ideal way of clean, sustainable energy. However, the oxygen evolution reaction (OER), a half reaction in water electrolysis, has a high theoretical potential barrier (1.23 V) and multiple electron transfer steps causing poor kinetics, low efficiency. The conventional noble metal oxide for OER (IrO2, RuO¬2) are rare and too expensive for large scale application. It is necessary to have an OER catalyst with low-cost, high catalytic efficiency, and long-term stability to break through the bottleneck. In this work, we improved the catalytic efficiency of cobalt and manganese oxide hydroxide thin film (CMOH) by two different strategies. The first method is synthesis of other metal oxide systems apart from just cobalt and manganese. We choose iron and nickel as the resource of metal ions, and successfully synthesize the iron and manganese, and nickel and manganese oxide thin film. Iron can also play an excellent dopant into CMOH thin film, a Co, Fe, Mn trimetallic thin film has an overpotential (ƞ) 345 mV at current density 10 mA·cm-2, reducing ƞ of 163 mV compare to CMOH thin film. The second method is dividing the continuous CMOH thin film to many small pieces, producing more interfaces containing the catalyst, conductive substrate, and the electrolyte, increasing the active sites and the activity of CMOH thin film. We then built a series of CMOH thin films with different continuity. That one with the maximum discontinuity has only 1/188 coverage area, but reduce a ƞ of 326 mV (at 30 mA·cm-2) and show a 56 times TOF increasing compare to the continuous one. It can also generate a highly current density of 330 mA·cm-2 and maintain its stability for 720 hours.. The result reveals that a both strategies can improve the intrinsic activity of CMOH, reduce the energy consume, and give a higher atomic efficiency in oxygen evolution, realizing a low-cost, high efficiency, and sustainable water electrolysis.
Tzeng, Wei-Gang, and 曾威綱. "The Barrier Effect of Electroless Cobalt Alloy Thin Film on Cu/Si Diffusion." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/n42c5d.
Повний текст джерела逢甲大學
材料科學所
90
The Co-W-P alloy thin film with thickness of 55 nm exhibits good diffusion barrier between Cu and Si. After rapidly thermal annealing at 700℃ for 30 seconds, the barrier performance is not degenerated. The pretreatment of substrate for the deposition of Co-W-P thin film is very important to the barrier quality. Barrier layers with 6.5wt% W shows the best barrier result aqmong Co-W-P coatings. The post-treatment of Co-W-P thin film by heating under hydrogen atmosphere would lower the sheet resistance of thin film. Some impurities of Co-W-P film may be removed by hydrolysis in H2 atmosphere. The corrosion resistance of Co-W-P thin film was evaluated. The corrosion rate of copper can be slowed down if Co-W-P thin film is used as capping layer of Cu. The passivation region of Co-W-P can be enlarged as W content in thin film is increased.
Huang, Yonghao, and 黃勇豪. "Fabrication of the ferrite microwave absorbers and the thin film Cu(In,Ga)Se2 solar cell." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/28892942429192029828.
Повний текст джерела國防大學理工學院
化學工程碩士班
100
In this study, the ferric components of microwave absorbers such as BaFe12O19 and Fe3O4 were prepared using aqueous combustion synthesis and chemical co-precipitation method, respectively. The composite of microwave absorbers were produced by carbon black, β-SiC and ferrites blending in TPR resin matrix. X-ray diffractomer, SEM, VSM were used to invegate the crystal structures, microstructures and magnetic properties of inorganic compoent in absorbers. The microwave properties and the reflection loss of absorbers had measured with HP8527B net work analyzer. For the fabrication of the thin film CIGS(Cu(In,Ga)Se2) solar cell, the absorption layer, CIGS, was sputtered Mo, Cu, Cu-Ga alloy and In metals sequencely on the surface of soda-lime glass by using RF energy source. The selenation was carried out with Se element at 525℃ in the final step. Buffer layer(CdS) was finished by precipitation method. ZnO and conducting ITO were deposited on the top of CdS layer by RF energy source too. The photoelectronic properties and the efficiency of CIGS solar cells were also measured and study in this research.
Yan, Tzyy Ching, and 顏子卿. "Research of hexagonal Sr-ferrite thin films with an easy axis perpendicular to the film plan." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/25889740103305374910.
Повний текст джерелаHuang, Zheng-chang, and 黃政昌. "Study of cobalt sulfide thin film prepared by electrodeposition and its application in supercapacitors." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/77949388235036316424.
Повний текст джерела大同大學
化學工程學系(所)
104
In this study, the reduction mechanism of cobalt sulfide has been investigated by using cyclic voltammetry (CV) and X-ray photoelectron spectroscopy (XPS). The reduction equation is [CoTU]2+ + 2e- →CoS + 2CN- + 2NH4+ + TU .According to the results of role of thiourea(TU) by using a microfluidic device, we can find the current be lower when the concentration change to 1M. We can observe the equilibrium voltage become large when the concentration of TU raised by using Tafel analysis and it exhibit the large impedance when the concentration of TU go up by using Electrochemical impedance spectroscopy(EIS).according to the results,the role of TU in the electrolyte might serve as an inhibitor. We also successfully prepare Co9S8 on Nickel foam substrate by using pulse-reversal deposition. It is high capacitance and good rate capability at 750mM TU and 1M TU. The electroactive materials delivered remarkable specific capacity up to 159 mAhg-1 and 193mhAg-1 at 2Ag-1. The retained ratio of capacitance of both is 71% and 60% with 2Ag-1 to 32Ag-1. Finally in this study, we try to change the structure of Co9S8 by using additive (Cetyltrimethylammonium bromide,CTAB or Polyethylene glycol hexadecyl ether,brij58) to the electrolyte. According to the results, the additive CTAB has no effects. But brij58 made the flaky structure of Co9S8 be small. Therefore, we will still use the brij58 in our study.
Chin-WeiHsu and 許峻維. "Study of Cobalt-doped Zinc oxide thin film deposited by pulsed Laser deposition and RF sputter." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/91042186446195533708.
Повний текст джерела國立成功大學
物理學系
102
ABSTRACT SUMMARY Based on previous study, we have already improve the luminous efficiency of light-emitting diodes (LEDs) by depositing zinc oxide related materials thin film between electrode layer and n-GaN layer. Although we get similar results by depositing cobalt doping zinc oxide on pulse laser deposition(PLD), the precise mechanisms that improve luminous efficiency have not confirm. In this research, we assume zinc oxide thin film will reduce the Efficiency droop effect. In order to solve PLD method can't deposit large size chip which is hard to apply by LEDs industry, we use sputter to reconfirm our result. In this research we focus on cobalt doping zinc oxide structure deposited by sputter and compare with PLD thin film. We use X-ray absorption spectrum including (XAS,XANES,EXAFS) and X-ray diffraction method to analyze our thin film. By changing different depositing parameters(Hydrogen, Temperature, Pressure, Percentage), we can observe the difference between each structure. In this research, we find out that Hydrogen can induce Hydrogen interstitial or oxygen vacancy. When the temperature raising, there are few cobalt interstitial will be observed and the amount of oxygen vacancy will also change. Pressure can also affect thin film structure. We use two target to modulate the percentage of cobalt doping in zinc oxide. At the end, we find out that under depositing parameters(temperature:400℃,pressure: 3.75E-3 mbar, Hydrogen mixed, power: 70w)can get the similar structure to previous result. Key word: Sputter, ZnO , XAS, Efficiency droop INTRODUCTION Light emitting diodes are one of the most important components in optoelectronic industry. Because of low power consumption, high lift time and fast reaction, LEDs research attracts increasing attention in the energy-price-up surging era. Some materials such as GaP, GaAs have been commonly used in yellow-blue LEDs. Facing strong global competition in full color LED industry, developing of high efficiency blue LEDs for illumination are ranged from 130-150 lm/W. Ideally, increasing the LED driving current enables the same lumen output to be achieved with less LED chips or using smaller LEDs. Unfortunately, this straightforward route to cost-per-lumen reduction is not readily available in actual GaN LEDs, One of the most significant challenges facing high-power and large size GaN-based LEDs is the efficiency droop effect which means the decrease in external quantum efficiency (EQE)of an LED with increasing injection current in quantum well. Peak internal quantum efficiency (IQE) occurs at relatively low-current densities , then rolls off as current density increases. Typical GaN-based LEDs have a peak in efficiency, typically at current densities less than 10 A/cm2, above which the efficiency gradually decreases. Despite having been the subject of extensive research efforts for a decade, the physical origin of droop has not been clarified. Several mechanism have been proposed to explain this LED droop effect, including electron leakage, poor hole injection, delocalization carriers, Auger recombination. In this research, we deposit cobalt doping zinc oxide thin film on n-GaN try to modulate mobility of n-GaN which can improve poor hole injection. Based on several reference, n-GaN mobility and carrier concentration will influence efficiency droop effect. Zinc oxide (ZnO), a wide bandgap (3.4 eV) II-VI compound semiconductor, has a stable wurtzite structure with lattice spacing a = 0.325 nm and c = 0.521 nm. It has attracted intensive research effort for its unique properties and versatile applications in transparent electronics. X-ray Absorption Spectroscopy (XAS) includes both Extended X-Ray Absorption Fine Structure (EXAFS) and X-ray Absorption Near Edge Structure (XANES). X-ray absorption spectra also contain information about the valence state of elements in materials. If the element is present as a cation, the absorption edge is shifted to lower (higher) photon energy because of the lower (higher) ionization potential The “X-ray absorption near edge structure” (XANES) is due to transitions into unoccupied bound states below the edge of the continuum. The “Extended X-ray absorption fine structure” (EXAFS) above the edge is due to backscattering of the photoelectron to the emitting atom. In our research, we use XRD method to check that lattice distance change and secondary phase form when growth parameters change. But XRD can't precise observe whether cobalt substitute zinc place or not, and this method can just determine cobalt interstitials and vacancy formed roughly by lattice distance changed. So we use XAS to analyze thin film structure more precisely. MATERIALS AND METHODS We deposit cobalt doping zinc oxide by sputter. First, we compare two conditions, one is pure Ar gas, the other is 5% H2 gas mixed. Second, we modulate different parameters, for example, temperature:(400-750℃),pressure(1E-2,3.75E-3,1E-3mbar), power:70w.Third,we use two targets(ZnO,CZO) with different power to modulate cobalt percentage in zinc oxide. Last, we compare with PLD thin film, which substrate temperature is 300℃,frequency is 2HZ, energy is 40mJ. X-ray Absorption(XAS,XANES, EXAFS) is measured in NSRRC 20A,07 beamline in Taiwan. Structural characterization was carried out by X-ray diffraction (XRD). Surface characterization was carried out by SEM, thickness of thin film was carried out by α-step, all were measuring in NCKU. RESULTS AND DISCUSSION First, we compare with the pure argon gas condition and five percentage hydrogen gas mixed condition. In XRD result, we can rule out secondary phase formed and we can observe a slightly move at 34 degree toward small angle when hydrogen gas mixed. It implies lattice distance increase that may cause by hydrogen interstitial. In XAS spectrum we can observe oxygen vacancy formed. In cobalt L-edge spectrum can find out that unoccupied states of cobalt are increasing when hydrogen mixed with argon and oxygen unoccupied states are decreasing. Because of oxygen vacancy formed, the amount of oxygen is decrease which hybridization with cobalt. This cause the peak and area in oxygen K-edge spectrum decrease. In XANES and EXAFS spectrum, we can rule out cobalt is metallic or cobalt oxide form in crystal, because of the shape of our spectrum is totally different to reference. So that we can confirm that cobalt substitute zinc. Second, we change different substrate temperature from 400-750℃. In XRD spectrum, we observe the lattice distance decrease when temperature raised. So we assume that hydrogen will escape from substrate when temperature raised. So the ability of forming oxygen vacancy decrease. In XAS spectrum, we can find out that the amount of oxygen vacancy decrease and unoccupied states increase in oxygen K-edge spectrum when temperature raised. At 750℃,the unoccupied states of oxygen are decrease. Based on reference, it may cause by cobalt interstitial. In XANES and EXAFS spectrum, we can confirm that cobalt substitute zinc whether temperature change or not. Because the cobalt interstitials amount are small, so it can't influence XRD and EXAFS spectrum. Third, we modulate pressure parameter (1E-2,3.75E-3,1E-3mbar),and we find out 3.75E-3 mbar is the better parameter of our sputter system. Obviously, the 3.75E-3 mbar condition FWHM of ZnO(002) peak is more narrow then the other. And photon energy of1E-2,1E-3mbar condition are shifting toward small angle that means the cobalt valence are more approaching to zero. Fourth, we can successfully use ZnO and CZO targets to deposit different cobalt percentage thin film by modulate different power of target, but sacrifice thin film quality. In XAS spectrum, different power of ZnO target can lead different cobalt behavior hybrid with oxygen. Last, we compare PLD with sputter result, we can observe at (temperature:400℃,pressure: 3.75E-3 mbar, Hydrogen mixed, power: 70w) this condition the structure that sputter is similar to PLD result whether in XRD or XAS spectrum. Although, the peak shape are slightly different, we approach our initial goal. CONCLUSION In Hydrogen condition, argon mix Hydrogen can produce oxygen vacancy but also formed some interstitial site. In Temperature condition, when the substrate temperature raise up, we can observe that may decrease hydrogen interstitial and little cobalt interstitials formed at 750.In Pressure condition,3.75E-3mbar is a better growth pressure in our system. In Co-sputter condition, we can modulate Co concentration by using CZO and ZNO target Co-sputter. But quality of thin film we be destroy slightly. we find out the growth condition at(temperature:400℃,pressure: 3.75E-3 mbar, Hydrogen mixed, power: 70w)can approach our previous PLD result. Because of the poor electrical properties of CZO film by sputter, we have to co-doping other materials( Al, Ga…) to improve its electrical properties. Then we can deposit on GaN substrate to check our result and apply on LED.
Lu, C. L., and 魯成龍. "Growth mechanism and structure of ultra-thin Cobalt film and Co/ Cr superlattice made by MBE method." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/87987165669028847043.
Повний текст джерелаLin, Long-Yi, and 林隆奕. "Additives Affecting the Growth of Cu Thin Film Prepared on Cobalt-Based Substrates by Electrochemical Atomic Layer Deposition." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/er4432.
Повний текст джерела國立虎尾科技大學
材料科學與工程系材料科學與綠色能源工程碩士班
104
The effect of the additives on electrochemical-atomic-layer-deposited copper film on Co/SiO2/Si substrate was investigated. An underpotentially -deposited (UPD) Pb atomic layer was used as a sacrificial layer. The following Cu film was prepared using surface limiting redox reaction in copper solution with different additives. Additives significantly affect the replacement of UPD – Pb by Cu. The resistance of the film was measured by four points probe. Crystal structure was analyzed by x-ray diffraction. The surface morphology was analyzed by scanning electron microscope and atomic force microscope. Corrosive effect of the additives on cobalt film was analyzed by electrochemical analyzer. The results showed that lead residual exist in Cu film when adding sodium citrate because sodium citrate reduces the efficiency of copper displacement. On the other hand, sodium perchlorate increases crystallinity and electrical properties of the Cu film. However, the high content of Cu2+ ions in solution enhances the galvanic corrosive on the cobalt film, resulting in the poor adhesion of copper film. Ethylenediamine increases the replacement efficiency of copper film and reduces the corrosion of cobalt film. Thus, the Cu film can be stabilized. In the second part of the study, we investigated the thermal stability of the added ethylenediamine in copper solution to prepare copper film on CoP and CoWP substrates using EC-ALD. The results showed that the copper film can be successfully deposited on the electroless cobalt-based substrate by EC-ALD. The Cu on CoP substrate is thermally stable up to 550oC, and Cu on CoWP substrate is thermally stable at 500oC.
Crozier, Brendan Matthew. "Electrodeposition of iron-cobalt alloys from a dibasic ammonium citrate stabilized plating solution." Master's thesis, 2009. http://hdl.handle.net/10048/558.
Повний текст джерелаMaterials Engineering
SIAO, JHAO-YU, and 蕭兆育. "Effects of Thin Film Metallic Glass on Cobalt High-Speed Steel Drill Bits in Dry Machining of 7075 Aluminum Alloy." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/16623275840478665093.
Повний текст джерела國立臺灣科技大學
材料科學與工程系
105
In machining industries, dry machining will be considered as a necessity in the near future since it is economically and ecologically desirable. To meet the specific requirement for dry machining, the development of coatings on commonly used cutting tools has been built. These coatings must have abilities to withstand high temperature and reduce friction as “solid lubricants” at the same time. Thus, high-hardness coatings have been widely use for cutting tools to improve durability in dry machining. In recent decade, novel coatings with low coefficient of friction such as TFMGs have been developed. Unique properties of thin film metallic glasses (TFMGs) such as low coefficient of frictions, smooth surface, high strength and toughness, as well as corrosion and wear resistance, have been identified owing to amorphous structure. Thus, TFMGs are thought to be potential materials for machining tools. In this study, Zr-based TFMG (ZrCuAlNi) coated cobalt high-speed steel drill bits were prepared. A milling machine was used for drilling test at constant rotational speed and feed rate. The thrust forces and torques in drilling 7075 aluminum alloy blocks were measured by dynamometer. TFMG-coated drill bits reduced an average ~56% thrust force and had relatively low applied torque during drilling against aluminum alloy blocks, referring better chip removal ability. The lower force increment and applied torque further indicated better wear resistance since no wear or scratch were found in TFMG-coated drill bits by scanning electron microscopy (SEM), the durability then seemed to be better. Keywords: Dry machining; Drill bit; solid lubricant; Thin film metallic glass; Low COF; wear resistance
Sai, Ranajit. "Development of CMOS-Compatible, Microwave-Assisted Solution Processing of Nanostructured Zine Ferrite Films for Gigahertz Circuits." Thesis, 2013. http://etd.iisc.ac.in/handle/2005/3412.
Повний текст джерелаSai, Ranajit. "Development of CMOS-Compatible, Microwave-Assisted Solution Processing of Nanostructured Zine Ferrite Films for Gigahertz Circuits." Thesis, 2013. http://etd.iisc.ernet.in/2005/3412.
Повний текст джерелаHong, Jia-Yang, and 洪嘉陽. "Effects of radio-frequency powers on properties of p-type amorphous cobalt carbon thin film alloys prepared by reactive sputtering deposition." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/79528021435165084663.
Повний текст джерела國立中興大學
材料科學與工程學系所
103
This study prepares p-type amorphous cobalt carbon (a-CoC) thin film alloys at different radio-frequency (RF) powers using reactive sputtering deposition, and investigates the microstructures, optical, and electrical properties of a-CoC thin film alloys. Moreover, the p-type a-CoC thin film alloys with identical thickness of 100 nm are deposited on n-type silicon substrates to fabricate a-CoC/n-Si device, and the properties of this device are also studied. Experimental results indicate that as the RF power increases from 50 to 250 W, the deposition rate rises; XPS results show that the cobalt/carbon ratio increases from 2.8 to 59.2%, and the sp2 carbon fraction of a-CoC thin film alloys increases from 24 to 60%; and Raman results indicate that ID/IG increases from 0.66 to 1.55. Additionally, as the RF power increases from 50 to 250 W, the optical band gap of a-CoC thin film alloys decreses from 2.16 to 0.17 eV and the resistivity decreases from 3.9×102 to 3.8×10-4 Ω·m. This is because the cobalt content in the a-CoC thin film alloys increases and their structure changes into metal. At the RF power of 100 W, the a-CoC/n-Si device has an optimal ideality factor of 1.6, and its built-in voltage is 0.51 V.
Balu, R. "Investigations On The Influence Of Process Parameters On The Deposition Of Samarium Cobalt (SmCo) Permanent Magnetic Thin Films For Microsystems Applications." Thesis, 2005. https://etd.iisc.ac.in/handle/2005/1068.
Повний текст джерелаBalu, R. "Investigations On The Influence Of Process Parameters On The Deposition Of Samarium Cobalt (SmCo) Permanent Magnetic Thin Films For Microsystems Applications." Thesis, 2005. http://hdl.handle.net/2005/1068.
Повний текст джерела