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W and two-dimensional WO3/W nanocrystals produced by controlled self-sustaining reduction of sodium tungstate

  • Khachatur V. Manukyan (a1), Albert A. Voskanyan (a2), Sergei Rouvimov (a3), Alexander S. Mukasyan (a4) and Suren L. Kharatyan (a5)...


The influence of calcium fluoride (CaF2) on combustion characteristics of Na2WO4 + 3 Mg system and microstructure of the produced W and WO3/W crystals is investigated. The results of thermodynamic analysis and experimental investigations show that CaF2 simultaneously enhances the conversion of Na2WO4 toward tungsten and binds sodium through the formation of NaF phase. The examination of the microstructure of quenched combustion products and differential scanning calorimetry analysis indicate that at early stages of combustion, a part of Na2WO4 is reduced by Mg to tungsten, whereas another part reacts with CaF2 forming CaWO4 and NaF. Subsequent magnesium reduction of CaWO4 significantly increases the overall temperature of the combustion process. Such modification in reaction mechanism coupled with postcombustion processing (e.g., acid/basic treatment) of the product allows us to produce either pure tungsten nanocrystals or tungsten oxide—tungsten nanostructures consisting of two-dimensional WO3 nanoflakes assembled on a W core. It is found that CaF2 does not influence the sizes of tungsten nanocrystals. However, since the addition of CaF2 leads to the increase of overall reaction temperature, it facilitates the formation of W particles with equilibrium crystal shape by faceting process.


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1.Lassner, E. and Schubert, W.D.: Tungsten: Properties, Chemistry, Technology of the Element, Alloys, and Chemical Compounds (Kluwer Academic/Plenum Publishers, New York, 1999), pp. 713.
2.Koutsospyros, A., Braida, W., Christodoulatos, C., Dermatas, D., and Strigul, N.: A review of tungsten: From environmental obscurity to scrutiny. J. Hazard. Mater. 136, 1 (2006).
3.Cha, S.I., Hong, S.H., and Kim, B.K.: Spark plasma sintering behavior of nanocrystalline WC–10Co cemented carbide powders. Mater. Sci. Eng., A. 351, 31 (2003).
4.Beste, U. and Jacobson, S.: A new view of the deterioration and wear of WC/Co cemented carbide rock drill buttons. Wear 264, 1129 (2008).
5.Samanta, S.K., Yoo, W.J., Samudra, G., Tok, E.S., Bera, L.K., and Balasubramanian, N.: Tungsten nanocrystals embedded in high-k materials for memory application. Appl. Phys. Lett. 87, 113110 (2005).
6.Chen, G.S., Yang, L.C., Tian, H.S., and Hsu, C.S.: Evaluating substrate bias on the phase-forming behavior of tungsten thin films deposited by diode and ionized magnetron sputtering. Thin Solid Films 484, 83 (2005).
7.Rossnagel, S.M., Noyan, I.C., and Cabral, C.: Phase transformation of thin sputter-deposited tungsten films at room temperature. J. Vac. Sci. Technol., B 20, 2047 (2002).
8.Sahoo, P.K., Srinivas, S., Kamal, K., Durai, L., and Sreedhar, B.: Chemical, structural, and morphological characterization of tungsten nanoparticles synthesized by a facile chemical route. J. Mater. Res. 26, 652 (2011).
9.Chen, C.H., Chang, T.C., Liao, I.H., Xi, P.B., Hsieh, J., Jason, C., Tensor, H., Sze, S.M., Chen, U.S., and Chen, J.R.: Tungsten oxide/tungsten nanocrystals for nonvolatile memory devices. Appl. Phys. Lett. 92, 013114 (2008).
10.Yang, S., Wang, Q., Zhang, M., Long, S., Liu, J., and Liu, M.: Titanium–tungsten nanocrystals embedded in a SiO2/Al2O3 gate dielectric stack for low-voltage operation in non-volatile memory. Nanotechnology 21, 245201 (2010).
11.German, R.M., Ma, J., Wang, X., and Olevsky, E.A.: Processing model for tungsten powders and extension to nanoscale size rang. Powder Metall. 49, 1927 (2006).
12.Wei, Q., Ramesh, K.T., Schuster, B.E., Kecskes, L.J., and Dowding, R.J.: Nanoengineering opens a new era for tungsten as well. JOM 58, 40 (2006).
13.Ricceri, R. and Matteazzi, P.: A study of formation of nanometric W by room temperature mechanosynthesis. J. Alloys Compd. 358, 71 (2003).
14.Moitra, A., Kim, S., Kim, S.G., Park, S.J., German, R.M., and Horstemeyer, M.F.: Investigation on sintering mechanism of nanoscale tungsten powder based on atomistic simulation. Acta Mater. 58, 3939 (2010).
15.Zhou, Z., Ma, Y., Du, J., and Linke, J.: Fabrication and characterization of ultra-fine grained tungsten by resistance sintering under ultra-high pressure. Mater. Sci. Eng., A 505, 131 (2009).
16.Gromov, A., Kwon, Y.S., and Choi, P: Interaction of tungsten nanopowders with air under different conditions. Scr. Mater. 52, 375 (2005).
17.Gleiter, H.: Nanocrystalline materials. Prog. Mater. Sci. 33, 223 (1989).
18.Gao, Y., Zhao, J., Zhu, Y., Ma, S., Su, X., and Wang, Z.: Wet chemical process of rod-like tungsten nanopowders with iron (II) as reductive agent. Mater. Lett. 60, 3903 (2006).
19.Sahoo, P.K., Kamal, S.S.K., Premkumar, M., Kumar, T.J., Sreedhar, B., Singh, A.K., Srivastava, S.K., and Sekhar, K.C.: Synthesis of tungsten nanoparticles by solvothermal decomposition of tungsten hexacarbonyl. Int. J. Refract. Met. Hard Mater. 27, 784 (2009).
20.Nersisyan, H.H., Lee, J.H., and Won, C.W.: A study of tungsten nanopowder formation by self-propagating high-temperature synthesis. Combust. Flame 142, 241 (2005).
21.Nersisyan, H.H., Won, H.I., Won, C.W., and Cho, K.C.: Combustion synthesis of nanostructured tungsten and its morphological study. Powder Technol. 189, 422 (2009).
22.Manukyan, K.V., Kharatyan, S.L., Mnatsakanyan, R.A., Zurnachyan, A.R., Voskanyan, A., and Danghyan, V.T.: Combustion synthesis of tungsten containing ceramic materials. 12th International Ceramics Congress (CIMTEC), Montecatini Term, Italy, 2010, p. 34.
23.Guojian, J., Jiayue, X., Hanrui, Z., and Wenlan, L.: Combustion synthesis of tungsten powder from sodium tungstate. Mater. Sci. Eng., B 176, 1037 (2011).
24.Guojian, J., Jiayue, X., Hanrui, Z., and Wenlan, L.: Fabrication of tungsten powder with sodium tungstate as raw material by SHS method. Mater. Lett. 65, 29692971 (2011).
25.Voskanyan, A.A., Niazyan, O.M., Manukyan, K.V., Kharatyan, S.L., Mnatsakanyan, R.A., and Mukasyan, A.S.: Mechanism for SHS-reduction of Na2WO4 by Mg. 11th International Symposium on Self-propagating High-temperature Synthesis, Anavyssos, Attica, Greece, 2011, p. 251.
26.Shiryaev, A.A.: Thermodynamics of SHS processes: An advanced approach. Int. J. SHS 4, 351 (1995).
27.Kalantar-zadeh, K., Vijayaraghavan, A., Ham, M.H., Zheng, H., Breedon, M., and Strano, M.S.: Synthesis of atomically thin WO3 sheets from hydrated tungsten trioxide. Chem. Mater. 22, 5660 (2010).
28.Merzhanov, A.G., Rogachev, A.S., Mukasyan, A.S., and Khusid, B.M.: Macrokinetics of structural transformation during the gasless combustion of a titanium and carbon powder mixture. Combust. Explos. Shock Waves 26, 92 (1990).
29.Jin, S.P., Lin, Shen Q., Zhan, L. and Jiang, Q.: Growth mechanism of TiCx during self-propagating high-temperature synthesis in an Al−Ti−C System. Cryst. Growth Des. 10, 1590 (2010).
30.Lima, C.L., Saraiva, G.D., Freire, P.T.C., Maczka, M., Paraguassu, W., Sousae, F.F., and Filho, J.M.: Temperature-induced phase transformations in Na2WO4 and Na2MoO4 crystals. J. Raman Spectrosc. 42, 799 (2011).
31.Lee, J.H., Jung, J.C., Borovinskaya, I.P., Vershinnikov, V.I., and Won, C.W.: Preparation of tungsten powder by the combustion of CaWO4/Mg. Met. Mater. Int. 6, 73 (2000).
32.Wang, L.L., Munir, Z.A., and , Y.M.: Maximov: Thermite reactions: Their utilization in the synthesis and processing of materials. J. Mater. Sci. 28, 3693 (1993).
33.Odawara, O., Mori, K., Tanji, A., and Yoda, S.: Thermite reaction in a short microgravity environment. J. Mater. Synth. Process. 1, 203 (1993).
34.Mei, J., Halldearn, R.D., and Xiao, P.: Mechanisms of the aluminium-iron oxide thermite reaction. Scr. Mater. 41, 541 (1999).
35.Durães, L., Costa, B.F.O., Santos, R., Correia, A., Campos, J., and Portugal, A.: Fe2O3/aluminum thermite reaction intermediate and final products characterization. Mater. Sci. Eng., A, 465, 199 (2007).
36.Bae, J.H., Kim, D.K., Jeong, T.H., and Kim, H.J.: Crystallization of amorphous Si thin films by the reaction of MoO3/Al nanoengineered thermite. Thin Solid Films 518, 6205 (2010).
37.Manukyan, K.V., Davtyan, D.H., Bossertand, J., and Kharatyan, S.L.: Direct reduction of ammonium molybdate to elemental molybdenum by combustion reaction. Chem. Eng. J. 168, 925 (2011).
38.Aydinyan, S.V., Gumruyan, Z., Manukyan, K.V., and Kharatyan, S.L.: Self-sustaining reduction of MoO3 by the Mg–C mixture. Mater. Sci. Eng., B 172, 267 (2010).
39.Manukyan, K.V., Kirakosyan, K.G., Grigoryan, Y.G., Niazyan, O.M., Yeghishyan, A.V., Kirakosyan, A.G., and Kharatyan, S.L., Mechanism of molten-salt-controlled thermite reactions. Ind. Eng. Chem. Res. 50, 10982 (2011).


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