Nanoenergetic materials nEMs have improved performances compared to their bulk counterpart or microcounterpart. The authors propose an approach to synthesize an Al/CuO based nEM that has several advantages over previous investigations such as enhanced contact, reduced impurities and Al oxidation, tailored dimensions, and easier integration into microsystem. CuO nanowires are synthesized by thermally annealing Cu film deposited onto silicon. Nano-Al is integrated with the nanowires to realize an Al/CuO based nEM. The synthesized nEM is characterized by scanning electron microscopy, high resolution transmission electron microscopy, x-ray diffraction, differential thermal analysis, and differential scanning calorimetry

Alphonse, Pierre

Ardila Rodriguez, Gustavo Adolfo

Rossi, Carole

Tenailleau, Christophe

Zhang, Kaili

English

International audienceNanoenergetic materials nEMs have improved performances compared to their bulk counterpart or microcounterpart. The authors propose an approach to synthesize an Al/CuO based nEM that has several advantages over previous investigations such as enhanced contact, reduced impurities and Al oxidation, tailored dimensions, and easier integration into microsystem. CuO nanowires are synthesized by thermally annealing Cu film deposited onto silicon. Nano-Al is integrated with the nanowires to realize an Al/CuO based nEM. The synthesized nEM is characterized by scanning electron microscopy, high resolution transmission electron microscopy, x-ray diffraction, differential thermal analysis, and differential scanning calorimetry

HAL-INSA Toulouse

Development of a nano-Al/CuO based energetic material on silicon substrate

HAL: Hyper Article en Ligne

Crossref

HAL Université de Toulouse, et Toulouse INP

Open Archive Toulouse Archive Ouverte

   Open Archive Toulouse Archive Ouverte (OATAO)  OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible.  This is an author-deposited version published in: http://oatao.univ-toulouse.fr/  Eprints ID :  2459  To link to this article :  URL : http://dx.doi.org/10.1063/1.2785132 To cite this version : Zhang, Kaili and Rossi, Carole and Ardila Rodriguez, G.A. and Tenailleau, Christophe and Alphonse, Pierre ( 2007) Development of a nano-Al/CuO based energetic material on silicon substrate. Applied Physics Letters, vol. 91 (n° 11). p. 3117. ISSN 0003-6951 Any correspondence concerning this service should be sent to the repository administrator: staff-oatao@inp-toulouse.fr   Development of a nano-Al/CuO based energetic material on siliconsubstrateKaili Zhang,a,b Carole Rossi,a,c and G. A. Ardila RodriguezLAAS-CNRS, Université de Toulouse, 31077 Toulouse, France,Christophe Tenailleau and Pierre AlphonseCIRIMAT, 31062 Toulouse, FranceNanoenergetic materials nEMs have improved performances compared to their bulk counterpart ormicrocounterpart. The authors propose an approach to synthesize an Al/CuO based nEM that hasseveral advantages over previous investigations such as enhanced contact, reduced impurities and Aloxidation, tailored dimensions, and easier integration into microsystem. CuO nanowires aresynthesized by thermally annealing Cu film deposited onto silicon. Nano-Al is integrated with thenanowires to realize an Al/CuO based nEM. The synthesized nEM is characterized by scanningelectron microscopy, high resolution transmission electron microscopy, x-ray diffraction, differentialthermal analysis, and differential scanning calorimetry. © 2007 American Institute of Physics.DOI: 10.1063/1.2785132Nanoenergetic materials nEMs have shown improvedperformances in terms of energy release, ignition, and me-chanical properties compared to their bulk or microcounter-parts. As a class of nEMs, nanothermite composites, alsotermed as metastable intermolecular composites MICs,have been an extensive research subject.1,2 In MIC, oxidizerand fuel are mixed at nanoscale, thus leading to the enhancedreactivity caused by the reduced mass transport limitationsbetween the reactants. Different approaches have been em-ployed to synthesize MIC such as physical mixing of nan-opowders of fuel and oxidizer,3–5 sol-gel,6 aerogel,7 atomiclayer deposition,8 deposition of multilayer foils of oxidizerand fuel,9 integration of porous silicon with oxidizers,10 em-bedding Fe2O3 nanowires inside an Al film,11 and employ-ment of molecular self-assembly.12,13 In this study, Al/CuObased MICs are realized by integrating nano-Al with CuOnanowires grown from Cu thin film deposited onto siliconsubstrate. The fabricated MICs are characterized by scanningelectron microscopy SEM, high resolution transmissionelectron microscopy HRTEM, x-ray diffraction XRD, dif-ferential thermal analysis DTA, and differential scanningcalorimetry DSC.A 30 nm thick Ti film is deposited onto silicon followedby a 50 nm thick Cu film deposition by thermal evaporation.A 1 m thick Cu film is then deposited by electroplating.The substrate is cut into small chips that are cleaned in a HClsolution. The chips are heated in a horizontal tube furnace at450 °C for 5 h under static air and then cooled down natu-rally to 25 °C. During the heating, CuO nanowires growfrom the Cu film. Al is deposited by thermal evaporationonto the substrate with CuO nanowires. The deposited thick-ness on average across the sample of Al is set to be1.12 m in the thermal evaporator. The Al is deposited undera vacuum level of 510−6 mbar and the substrate tempera-ture is about 30 °C during the deposition. The Al/CuObased MICs on silicon are directly characterized by SEM andXRD. The heat of reaction of the MIC is determined by DTAand DSC. DTA is performed from 20 to 1000 °C with aheating rate of 15 °C/min under a 99.995% Ar flow. A massof 16.67 mg of the MIC is peeled from the substrate. DSC iscarried out from 20 to 700 °C at a heating rate of 5 °C/minunder a 99.999% N2 flow with a sample mass of 2.80 mg.Figure 1a shows a 30° tilted view SEM image of theannealed Cu film before Al deposition. CuO nanowires growfrom the Cu film after annealing. Figure 1b is a SEM imageof the nanowires after Al deposition. Nano-Al is uniformlyintegrated around the CuO nanowires, thus enhancing theinterfacial contact and the reactivity. The average diameter ofthe nanowires is about 40–80 nm. After Al deposition, theaverage diameter becomes around 150–250 nm. Figures 2aand 2b are cross-section view SEM images of the CuOnanowires before and after Al deposition. Al is both inte-grated with the CuO nanowires to form a core-shell nano-structure and also deposited onto the film under the nano-wires to form a layered structure.The compositions of the MIC are identified by XRD, asshown in Fig. 3. Al, CuO, and Cu2O diffraction lines can beseen from the XRD pattern. When Cu film is annealed instatic air, Cu is first converted into Cu2O. Then, CuO isformed slowly through a second step oxidation of Cu2O. Theinset picture in Fig. 3 is a HRTEM image of an individualnanowire. Each side of the nanowire is a single crystal witha distinct fringe space pattern. The interplanar spacing forone side is 2.46 Å and 1.99 Å for the other side; these inter-aAuthors to whom correspondence should be addressed.bElectronic mail: kailizhang@hotmail.comcElectronic mail: rossi@laas.frFIG. 1. 30° tilted view SEM images of the annealed Cu film a before Aldeposition and b after Al deposition.planar spacings are similar to those for 111 and 1−11planes in monoclinic CuO.14 There are no peaks for Al2O3and Cu, indicating that no significant reaction between Aland CuO/Cu2O occurs during the Al deposition due to thehigh vacuum level and low substrate temperature.The exothermic reaction of the MIC is characterizedwith DTA, as shown in Fig. 4. There are two major exo-therms. The first exotherm is observed with an onset tem-perature of about 500 °C, which means that the nanocom-posite seems to react prior to the melting of Al. This suggeststhat the first exotherm is caused by the thermite reactionbetween the CuO nanowires and nano-Al. The second exo-therm is found with an onset temperature of around 720 °C.After melting, the remaining Al reacts with the Cu2O andalso perhaps some CuO film under the CuO nanowires.To quantitatively determine the heat of reaction, theMICs are characterized with DSC, as shown in Fig. 5. Thefirst exothermic peak with an onset temperature of about500 °C, which corresponds to the first peak in DTA curve inFig. 4, is caused by the reaction between the CuO nanowiresand nano-Al. The second endothermic peak 660 °C iscaused by the melting of the remaining Al. Integration of thefirst exothermic peak in DSC gives a heat of reaction equalto 1085±160 J /g. Assuming that the DTA signal is propor-tional to the heat of reactions, we use the area of the firstpeak, calculated from DSC analysis, to scale the DTA curve.Though it is not accurate because the relationship betweentemperature and heat is not exactly linear, it allows us toroughly estimate the total heat of reaction of the MIC to beabout 2950 J /g. This value is between the theoretical heat ofreaction of CuO with Al 4067 J /g and Cu2O with Al2434 J /g.15 The performance of the MIC can be improvedby adjusting the dimensions of the CuO nanowires16 and bytuning the Al deposition to reach a stoichiometric reaction.Figure 6 shows the XRD pattern of the MIC after DTAtesting. The final reaction products are identified to be Al2O3,CuAlO2, and CuO. The Al peaks seen in Fig. 3 before reac-tion is no longer present. CuAlO2 is formed from the reac-tions of Al2O3 with CuO/Cu2O.17,18 However, XRD patterndoes not show the Cu lines that should be there afterCuO/Cu2O reduction by Al. The Cu produced fromAl/CuO/Cu2O thermite reactions is most likely oxidized byO2 contained in Ar flow and/or generated from the reactionof Al2O3 with CuO.18This approach has some advantages compared to previ-ous investigations. First, the MICs are realized by integratingnano-Al with CuO nanowires, thus enhancing the interfacialcontact and reactivity. Second, the presence of impurities andAl oxidation is smaller because the MICs are fabricated in aFIG. 2. Cross-section view SEM images of the annealed Cu film a beforeAl deposition and b after Al deposition.FIG. 3. Color online XRD scan of the Al/CuO based MIC before reactionand HRTEM image of an individual nanowire.FIG. 4. DTA plot of the Al/CuO based MICs.FIG. 5. DSC plot of the heat flow for the Al/CuO based MICs.high vacuum and with a low substrate temperature. Third,since the dimensions of CuO nanowires can be tailored,16 theoxidizer/fuel dimensions can be controlled at the nanoscale.Fourth, the process uses standard microfabrication technolo-gies and therefore it is suitable for mass production. TheMICs are deposited onto silicon, a basic material for micro-electronics and microsystem. Consequently, it is straightfor-ward to integrate the MIC into microsystem to resultin nanostructures, for example, high performancenanoigniters.2,19In conclusion, nano-Al/CuO based MICs have been re-alized by integrating nano-Al with CuO nanowires grownfrom Cu film deposited onto silicon. The Cu film is con-verted into bicrystal CuO nanowires and Cu2O and also per-haps some CuO film after annealing. After Al deposition,nano-Al is integrated with CuO nanowires to form a core-shell nanostructure and also deposited onto the film under thenanowires to form a layered structure. DTA and DSC resultssuggest that nano-Al reacts with CuO nanowires with an on-set temperature of about 500 °C prior to the melting of Al.After melting, the remaining Al reacts with the Cu2O andalso perhaps some CuO film beneath the CuO nanowires.The total heat of reaction is estimated to be about 2950 J /g.The MICs are realized onto silicon. Therefore, this will prob-ably open the door to the integration of the material intosilicon based microsystem, thus leading to functional nan-odevices.1A. W. Miziolek, AMPTIAC 6, 43 2002.2C. Rossi, K. Zhang, D. Estève, P. Alphonse, J. Y. C. Ching, P. Tailhades,and C. Vahlas, J. Microelectromech. Syst. 16, 919 2007.3J. J. Granier and M. L. Pantoya, Combust. Flame 138, 373 2004.4B. S. Bockmon, M. L. Pantoya, S. F. Son, B. W. Asay, and J. T. Mang, J.Appl. Phys. 98, 064903 2005.5A. Prakash, A. V. McCormick, and M. R. Zachariah, Adv. Mater. Wein-heim, Ger. 17, 900 2005.6T. M. Tillotson, A. E. Gash, R. L. Simpson, L. W. Hrubesh, J. H. Satcher,Jr., and J. F. Poco, J. Non-Cryst. Solids 285, 338 2001.7A. Prakash, A. V. McCormick, and M. R. Zachariah, Nano Lett. 5, 13572005.8J. D. Ferguson, K. J. Buechler, A. W. Weimer, and S. M. George, PowderTechnol. 156, 154 2005.9K. J. Blobaum, M. E. Reiss, J. M. P. Lawrence, and T. P. Weihs, J. Appl.Phys. 94, 2915 2003.10A. Hofmann, H. Laucht, D. Kovalev, V. Y. Timoshenko, J. Diener, N.Kunzner, and E. Gross, U.S. Patent No. 6,984,274 10 January 2006.11L. Menon, S. Patibandla, K. Bhargava Ram, S. I. Shkuratov, D. Aurong-zeb, M. Holtz, J. Berg, J. Yun, and H. Temkin, Appl. Phys. Lett. 84, 47372004.12S. H. Kim and M. R. Zachariah, Adv. Mater. Weinheim, Ger. 16, 18212004.13S. Subramaniam, S. Hasan, S. Bhattacharya, Y. Gao, S. Apperson, M.Hossain, R. V. Shende, S. Gangopadhyay, P. Redner, D. Kapoor, and S.Nicolich, MRS Symposia Proceedings No. 896 Materials Research Soci-ety, Pittsburgh 2006, p. 0896-H01-05.1.14Joint Committee on Powder Diffraction Standards File No. 45–0937,1991.15O. B. Kubaschewski, C. B. Alcock, and P. J. Spencer, Materials Thermo-chemistry, 6th ed. Pergammon, Oxford, 1993, pp. 259, 274, and 275.16K. Zhang, C. Rossi, C. Tenailleau, P. Alphonse, and J. Y. C. Ching, Nano-technology 18, 275607 2007.17J. H. Shy and B. H. Tseng, J. Phys. Chem. Solids 66, 2123 2005.18M. N. Spallart, S. P. Pai, and R. Pinto, “PLD Growth of CuAlO2,” ThinSolid Films in press.19T. W. Barbee, R. L. Simpson, A. E. Gash, and J. H. Satcher, U.S. PatentNo. WO 2005 016850 A2 24 February 2005.FIG. 6. XRD scan of the Al/CuO based MIC after DTA testing.

Scientific Publications of the University of Toulouse II Le Mirail

Development of a nano-Al/CuO based energetic material on silicon substrate

Abstract

Similar works

Full text

Available Versions