3,180 research outputs found
Influence Of Stress On The Field Emission Properties Of Amorphous Carbon Thin Films And Multiwall Carbon Nanotube-polymer Composites
No full textThe effects compressive stress on the field emission properties of amorphous carbon thin films and multiwall carbon nanotube (MWCN) polymer composites were investigated. In the study, the nanocrystalline films and MWNT composite thin films were subject to external stress by mechanical bending. The field emission results from C films with different intrinsic stresses were compared. The results showed that the threshold field increases with the increase in stress.194195Poa, C.H., Lacerda, R.G., Cox, D.C., Silva, S.R.P., Marques, F.C., (2002) Appl. Phys. Lett., 81, p. 85
Relatório de estágio no Inter de Milheirós F.C
No full textO referido estágio decorreu no Inter de Milheirós F.C., que disputou a Divisão de Honra da A.F. Porto e este relatório trata-se de um relato das atividades que decorrem ao longo da época desportiva, desde o contacto com o plantel, planeamento e execução de treino e relato do dia-a-dia de uma equipa de futebol. Deste documento farão parte exercícios de treino, no período pré-competitivo e durante a competição, relato do modelo de jogo adotado e os seus princípios e a inclusão do modelo de jogo no planeamento semanal de treino.N/
Effects Of Stress On Electron Emission From Nanostructured Carbon Materials
No full textThe electron field emission from a graphite like amorphous carbon film was investigated. Threshold fields as low as 8 V/νm were observed at an assisting energy of 400eV. The field emission characteristics of the films were explained in terms of the high sp2 concentration, and the high intrinsic compressive stress modifying the electronic band structure of the film/graphitic nanostructures.21417101714McKenzie, D.R., Muller, D., Pailthope, B.A., (1991) Phys. Rev. Lett., 67, p. 773Schwan, J., Ulrich, S., Theel, T., Roth, H., Ehrhardt, H., Becker, P., Silva, S.R.P., (1997) J. Appl. Phys., 82, p. 6024Lifshitz, Y., Kasi, S.R., Rabalais, J.W., Eckstein, W., (1990) Phys. Rev. B, 41, p. 10468Robertson, J., (1993) Diamond Relat. Mater., 2, p. 984Lacerda, R.G., Hammer, P., Lepienski, C.M., Alvarez, F., Marques, F.C., (2001) J. Vac. Sci. Technol. A, 19, p. 971Bhattacharyya, S., Subramanyam, S.V., (1997) Appl. Phys. Lett., 71, p. 632Kilic, C., Mehrez, H., Ciraci, S., (1998) Phys. Rev. B, 58, p. 7872Uher, C., Hockey, R.L., Ben-Jacob, E., (1987) Phys. Rev. B, 35, p. 4483Satyanarayana, B.S., Hart, A., Milne, W.I., Robertson, J., (1997) Appl. Phys. Lett., 71, p. 1430Carey, J.D., Forrest, R.D., Silva, S.R.P., (2001) Appl. Phys. Lett., 78, p. 2339Illie, A., Ferrari, C., Yagi, T., Robertson, J., (2000) Appl. Phys. Lett., 76, p. 2627De Lima M.M., Jr., Lacerda, R.G., Vilcarromero, J., Marques, F.C., (1999) J. Appl. Phys., 86, p. 4936Hoffman, R.W., (1966) Physics of Thin Films, 3, pp. 211-273. , edited by G. Hass and R. E. Thun (Academic, New YorkCarey, J.D., Silva, S.R.P., (2001) Appl. Phys. Lett., 78, p. 347Hammer, P., Victoria, N.M., Alvarez, F., (2000) J. Vac. Sci. Technol. A, 18, p. 2277Lifshitz, Y., Lempert, G.D., Grossman, E., Avigal, L., Uzan-Saguy, C., Kalish, R., Khlik, J., Rabalais, J.W., (1995) Diamond Relat. Mater., 4, p. 318Fallon, P.J., Veerasamy, V.S., Davis, C.A., Robertson, J., Amaratunga, G.A.J., Milne, W.I., Koskinen, J., (1993) Phys. Rev. B, 48, p. 4777Ahuja, R., Auluck, S., Trygg, J., Wills, J.M., Eriksson, O., Johansson, B., (1995) Phys. Rev. B, 51, p. 4813Reynolds, W.N., Goggin, P.R., (1960) Philos. Mag., 5, p. 1049Lynch, R.W., Drickamer, H.G., (1966) J. Chem. Phys., 44, p. 181Chaumet, P.C., Dufour, J.P., (1998) J. Electrost., 43, p. 145Hryd, R., Charlier, A., McRae, E., (1997) Phys. Rev. B, 55, p. 682
Relatório de estágio no Inter de Milheirós F.C
No full textO referido estágio decorreu no Inter de Milheirós F.C., que disputou a Divisão de Honra da A.F. Porto e este relatório trata-se de um relato das atividades que decorrem ao longo da época desportiva, desde o contacto com o plantel, planeamento e execução de treino e relato do dia-a-dia de uma equipa de futebol. Deste documento farão parte exercícios de treino, no período pré-competitivo e durante a competição, relato do modelo de jogo adotado e os seus princípios e a inclusão do modelo de jogo no planeamento semanal de treino.N/
Thermal Expansion Coefficient, Mechanical And Structural Properties Of Hydrogenated Carbon Nitrides
No full textAmorphous hydrogenated carbon nitride films (a-C:H:N) deposited by plasma enhanced chemical vapor deposition of methane (CH 4) and nitrogen (N 2), under low (- 200 V) and high (- 800 V) bias voltage are investigated. The nitrogen content was obtained from X-ray photoelectron spectroscopy and nuclear reaction analysis. Raman measurements were performed at 514 nm (visible) and 244 nm (UV) wavelengths. Mechanical properties (Young's modulus and hardness) and thermal expansion coefficient (TEC) were studied using the bending beam method. Raman spectroscopy shows that the incorporation of nitrogen in a-C:H reduces the disorder in the film, independent of the initial structure of the a-C:H films (tetrahedral-, diamond-, or graphitic-like). The TEC is related to the Raman parameters associated with the degree of sp 2 ordering (aromatic rings) in the film structure, increasing with the nitrogen incorporation. © 2012 Elsevier B.V. All rights reserved.25124127Morrison, N.A., Muhl, S., Rodil, S.E., Ferrari, A.C., Nesladek, M., Milne, W.I., Robertson, J., (1999) Phys. Status Solidi A, 172, p. 79Grill, A., (1998) Wear, 168, p. 143Grill, A., (1999) Diamond Relat. Mater., 8, p. 428Rodil, S.E., Milne, W.I., Robertson, J., Brown, L.M., (2000) Appl. Phys. Lett., 77, p. 1458Hu, J.T., Yang, P.D., Lieber, C.M., (1998) Phys. Rev. B, 57, p. 3185Lacerda, R.G., Marques, F.C., (1998) Appl. Phys. Lett., 73, p. 617Champi, A., Marques, F.C., Freire, F.L., (2004) Diamond Relat. Mater., 13, p. 1538Oliver, W.C., Pharr, G.M., (2004) J. Mater. Res., 19, p. 3Scheider, D., Meyer, C.F., Mai, H., Schoneich, B., Ziegele, H., Scheibe, H.J., Lifshitz, Y., (1998) Diamond Relat. Mater., 7, p. 973Stoney, G.C., (1909) Proc. R. Soc. Lond. A, 32De Lima, Jr.M.M., Lacerda, R.G., Vilcarromero, J., Marques, F.C., (1999) J. Appl. Phys., 86, p. 4936Hoffman, R.W., (1996) Physics of Non-metallic Thin Films, , Academic press New YorkMarques, F.C., Lacerda, R.G., Champi, A., Stolojan, V., Cox, D.C., Silva, S.R.P., (2003) Appl. Phys. Lett., 83, p. 3099Champi, A., Barbieri, P.F., Marques, F.C., (2006) J. Non-Cryst. Solids, 352, p. 2264Ferrari, A.C., Robertson, J., (2000) Phys. Rev. B, 61, p. 14095Ferrari, A.C., Robertson, J., (2001) Phys. Rev. B, 64, p. 075414Casiraghi, C., Ferrari, A.C., Robertson, J., (2005) Phys. Rev. B, 72, p. 085401Ferrari, A.C., Rodil, S.E., Robertson, J., (2003) Phys. Rev. B, 67, p. 155306Muhl, S., Mendez, J.M., (1999) Diamond Relat. Mater., 8, p. 180
Diamond Like Carbon Used As Antireflective Coating On Crystalline Silicon Solar Cells
No full textAmorphous carbon with different structures was used as antireflective coating on crystalline silicon solar cells. Polymeric-like carbon (PLC) and diamond-like carbon (DLC) were deposited by the PECVD technique on the anode and cathode electrode, respectively. Tetrahedral-like carbon (ta-C) was deposited by the filtered cathodic vacuum arc (FCVA). An increase in the short circuit current comparable to that obtained by conventional antireflective coating (SnO2) was obtained using PLC antireflective coating. The effect on the short circuit current of the other structures (DLC and ta-C) is reduced mainly due to the band gap and/or a mismatch on the index of refraction of the film and the crystalline silicon substrate. © 2009 Elsevier B.V. All rights reserved.185-810281030Birgin, E.G., Chambouleyron, I., Martínez, J.M., (1999) J. Comp. Phys., 151, p. 862M de Lima Jr., M., Lacerda, R.G., Vilcarromero, J., Marques, F.C., (1999) J. Appl. Phys., 86, p. 4936Marques, F.C., Urdanivia, J., Chambouleyron, I., (1998) Sol. Energy Mater. Sol. Cells, 52, p. 285Robertson, J., (2005) Daimond Relat. Mater., 14, p. 942Ferrari, A.C., Rodil, S.E., Robertson, J., Milne, W.I., (2002) Daimond Relat. Mater., 11, p. 994Lacerda, R.G., Hammer, P., Alvarez, F., Marques, F.C., (2001) J. Vac. Sci. Technol., A, 19, p. 971Polo, M.C., Andújar, J.L., Hart, A., Robertson, J., Milne, W.I., (2000) Daimond Relat. Mater., 9, p. 663Ager, J.W., Anders, S., Anders, A., Brown, I.G., (1995) Appl. Phys. Lett., 66, p. 3444McKenzie, D.R., Muller, D., Pailthorpe, B.A., (1991) Phys. Rev. Lett., 67, p. 773Schwan, J., Ulrich, S., Theel, T., Roth, H., Ehrhardt, H., Becker, P., Silva, S.R.P., (1997) J. Appl. Phys., 82, p. 6024Born, M., Wolf, E., (1975) Principles of Optics. 5th ed., , Pergamon, New YorkMarques, F.C., (1998) IEEE Trans. Electron Devices, 45, p. 161
Influence Of Hydrogen On The Thermomechanical Properties Of A-cnx:h And A-cnx Films Deposited By Glow Discharge And Ion Beam Assisted Deposition
No full textThe coefficient of thermal expansion (CTE), Young's modulus, Poisson's ratio, stress and hardness of a-CNx and a-CNx:H were investigated as a function of nitrogen concentration. Hydrogenated films were prepared by glow discharge, GD, and unhydrogenated films were prepared by ion beam assisted deposition, IBAD. Using nanohardness measurements and the thermally induced bending technique, it was possible to extract separately, Young's modulus and Poisson's ratio. A strong influence of hydrogen, in a-CNx:H films, was observed on the CTE, which reaches about ∼9 × 10-6 C-1, close to that of graphite (∼8 × 10-6 C-1) for nitrogen concentration as low as 5 at.%. On the other hand, the CTE of unhydrogenated films increases with nitrogen concentration at a much lower rate, reaching 5.5 × 10-6 C-1 for 33 at.% nitrogen. © 2006 Elsevier B.V. All rights reserved.35221-2222642266Liu, A.M., Cohen, M., (1989) Science, 245, p. 841Muhl, S., Mendez, J.M., (1999) Diam. Relat. Mater., 8, p. 1809Badzian, A., Badzian, T., (1999) Thin Solid Films, 354, p. 148Cutiongco, E.C., Li, D., Chung, Y.W., (1996) J. Tribol., 118, p. 543Robertson, J., (2001) Thin Solids Films, 383, p. 81Marques, F.C., Lacerda, R.G., Champi, A., Stolojan, V., Cox, D.C., Silva, S.R.P., (2003) Appl. Phys. Lett., 83, p. 3099Champi, A., Lacerda, R.G., Marques, F.C., (2003) Microelectr. J., 34, p. 553Champi, A., Marques, F.C., Freire, F.L., (2004) Diam. Relat. Mater., 13, p. 1538Hammer, P., Victoria, N.M., Alvarez, F., (2000) J. Vac. Sci. Technol. A, 18 (5), p. 2277de Lima Jr., M.M., Lacerda, R.G., Vilcarromero, J., Marques, F.C., (1999) J. Appl. Phys., 86, p. 4936Nelson, J.B., Riley, D.P., (1945) Proc. Phys. Soc. London, 57, p. 47
Esr Investigation Of Graphite-like Amorphous Carbon Films Revealing Itinerant States As The Ones Responsible For The Signal
No full textThe origin of paramagnetic centers in graphite-like amorphous carbon is investigated. The films were deposited by the ion beam assisted deposition (IBAD) and have a concentration of sp2 sites of about 90% and zero energy band gap. The density of the film and the electrical resistivity are close to these of crystalline graphite. However, the hardness and stress of the films are similar to those of diamond-like carbon. Electron spin resonance (ESR) performed at the X-band (9.4 GHz) revealed an unexpected low density of paramagnetic centers, ascribed to conduction electrons with a g-value of about 2.003. © 2008 Elsevier B.V. All rights reserved.35419-2521352137Robertson, J., (1996) PRB, 53 (24), p. 16302Barklie, R.C., (2001) Diam. Relat. Mater., 10, p. 174Lacerda, R.G., Hammer, P., Lepiensky, C.M., Alvarez, F., Marques, F.C., (2001) J. Vac. Sci. Technol. A, 19 (3), p. 971Poa, C.H., Lacerda, R.G., Cox, D.C., Silva, S.R.P., Marques, F.C., (2002) Appl. Phys. Lett., 81 (5), p. 853Sercheli, M.S., Kopelevich, Y., Ricardo da Silva, R., Torres, J.H.S., Rettori, C., (2002) Solid State Commun., 121, p. 579Von Bardeleben, H.J., Cantin, J.L., Zeinert, A., Racine, B., Zellama, K., Hai, P.N., (2001) Appl. Phys. Lett., 78 (19), p. 2843Hoinkis, M., Tober, E.D., White, R.L., Crowder, M.S., (1992) Appl. Phys. Lett., 61 (22), p. 265
Estudo comparativo dos métodos de análise do teor de matéria orgânica nos solos
No full textTCC (graduação) - Universidade Federal de Santa Catarina. Centro de Ciências Físicas e Matemáticas. Curso de Química.Com o objetivo de otimizar o método de análise do teor de matéria orgânica nos solos, foi realizado um estudo comparativo de três métodos na empresa CIDASC (Companhia Integrada de Desenvolvimento Agrícola de Santa Catarina) em Florianópolis. Os métodos comparados foram: o método da solução sulfocrômica, o método do digestor e o método PPI (perda de peso por ignição). O método da solução sulfocrômica é baseado na reação de oxi-redução, usando uma solução sulfocrômica para oxidar o carbono orgânico; o método do digestor é um método desenvolvido a partir do anterior, onde é fornecido à reação calor externo, acelerando a oxidação do carbono orgânico. O método da PPI, ou seja, perda de peso por ignição, é um método que se utiliza uma temperatura elevada para a queima da matéria orgânica. Os métodos da solução sulfocrômica e o método do digestor apresentaram uma boa correlação (R= 0,99387), visto que os dois métodos são baseados na quantização do carbono orgânico, assim apresentam as mesmas limitações. O método da PPI foi o método que apresentou maior teor de matéria orgânica para todas as amostras estudadas, mas mesmo assim apresentou boa correlação com os dois outros métodos. Pode-se considerar este o melhor método para análise do teor de matéria orgânica nos solos, mas também apresenta limitações, não sendo adequado para um solo com baixo teor de matéria orgânica
Diamond-like Carbon Deposited By Plasma Technique As A Function Of Methane Flow Rate
No full textDiamond-like carbon (a-C:H) prepared by plasma enhanced chemical vapor deposition (PECVD) as a function of methane gas flow rate is reported. Films deposited at zero flow rate, i.e., without the use of vacuum pumps during the deposition, are also investigated. For that purpose, the reactor chamber was baked and pumped down to about 10-8 Torr to reduce contamination released from the reactor walls. The films were analyzed by visible, infrared and Raman spectroscopes. It was observed that the deposition rate, hydrogen concentration and optical gap depend on the methane gas flow rate. A maximum for deposition rate found at methane flow was much smaller than the flow usually adopted in conventional procedures. © 2010 Elsevier B.V. All rights reserved.197-9756759Neuville, S., Matthews, A., (1997) MRS Bull., 22, p. 22Poa, C.H.P., Silva, S.R.P., Lacerda, R.G., Amaratunga, G.A.J., Milne, W.I., Marques, F.C., (2005) Appl. Phys. Lett., 86, p. 232102Amaratunga, G.A.J., Silva, S.R.P., (1996) Appl. Phys. Lett., 68, p. 2529Robertson, J., (2002) Mat. Sci. Eng., 37, p. 129Lifshiz, Y., (1999) Diamond Relat. Mater., 8, p. 1659Marques, F.C., Lacerda, R.G., Champi, A., Stolojan, V., Cox, D.C., Silva, S.R.P., (2003) Appl. Phys. Lett., 83 (15), p. 3099Silva, S.R.P., (2003) Properties of Amorphous Carbon, , EMIS Datareviews Series No. 29, INSPEC - IEE, London, United KingdomMacKenzie, D.R., Muller, D., Pailthorpe, B.A., (1991) Phys. Rev. Lett., 67, p. 773Lacerda, R.G., Marques, F.C., (1998) Appl. Phys. Lett., 73, p. 617Okano, K., Koizumi, S., Silva, S.R.P., Amaratunga, G.A.J., (1996) Nature, 381, p. 140Géis, M.W., Efremow, N.N., Krohn, K.E., Twichell, J.C., Lyszcazrz, T.M., (1998) Nature, 393, p. 431Suzuki, T., Kodama, H., (2009) Diam. Relat. Mater., 18, p. 990Chambouleyron, I., Ventura, S.D., Birgin, E.G., Martínez, J.M., (2002) J. Appl. Phys., 92, p. 3093Basa, D.K., Smith, F.W., (1990) Thin Solid Films, 192, p. 121Ristein, J., Stief, R.T., Ley, L., Beyer, W., (1998) J. Appl. Phys., 84 (7), p. 3836Zhang, W., Catherine, Y., (1991) Surf. Coat. Techn., 47, p. 69Ferrari, A.C., Robertson, J., (2000) Phys. Rev. B, 61 (20), p. 14095Casiraghi, C., Ferrari, A.C., Robertson, J., (2005) Phys. Rev. B, 72, p. 085401Robertson, J., (1996) Phys. Rev. B, 53, p. 1630
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