Investigación

 

A low–temperature and seedless method for producing hydrogen–free Si₃N₄

 

A.L. Leal–Cruz, M.I. Pech–Canul*, and J.L. de la Peña

 

Centro de Investigación y de Estudios Avanzados del IPN–Unidad Saltillo, Carr. Saltillo–Monterrey Km. 13. Saltillo, 25900 Coahuila, México.

 

* Corresponding author:
Phone: +52 (844) 438–9600 Ext. 9678. Fax: 438–9610,
e–mail: martin.pech@cinvestav.edu.mx, martin_pech@yahoo.com.mx

 

Recibido el 17 de septiembre de 2007
Aceptado el 3 de abril de 2008

 

Abstract

A simple, seedless method for the synthesis of Si₃N₄ from a hydrogen–free precursor system (Na₂SiF_6(s)–N_2(g)) was developed. From thermodynamic calculations and experimental results it is concluded that the gaseous chemical species SiF_x (SiF₄,SiF₃, SiF₂, SiF and Si) formed during the low–temperature dissociation of Na₂SiF₆ in a conventional CVD system react in–situ with nitrogen to produce Si₃N₄. Whiskers, fibers, coatings and powders were obtained via the Na₂SiF₆–N₂ system at pressures slightly above atmospheric pressure. Not only does the feasibility of the reactions for Na₂SiF₆ dissociation and Si₃N₄ formation increase with the temperature but also, once the SiF_x chemical species are formed by the former, the latter reaction is even more viable. Amorphous Si₃N₄ is obtained at temperatures of up to 1173 K while crystalline α– and β–Si₃N₄ are formed in the range 1273–1573 K and with processing times as short as 120 minutes. Optimal conditions for maximizing Si3N4formation were determined.

Keywords: Thermodynamics; CVD; Amorphous Si₃N₄; α– and β–Si₃N₄; gas–solid precursors.

 

Resumen

Se desarrolló un método simple y sin semillas para la síntesis de Si₃N₄ partiendo de un sistema de precursores libre de hidrógeno (Na₂SiF_6(s)–N_2(g)). A partir de cálculos termodinámicos y resultados experimentales se concluye que las especies químicas gaseosas SiF_x (SiF₄,SiF₃, SiF₂, SiF and Si) formadas durante la disociación a baja temperatura del Na₂SiF₆ en un sistema convencional de CVD reaccionan in situ con el nitrogeno para producir Si₃N₄. Se obtuvieron fibras, fibras cortas discontinuas, recubrimientos y polvos a través del sistema Na₂SiF_6(s)–N₂ a presiones ligeramente por encima de la presión atmosférica. Con el incremento en la temperatura no solo aumenta la factibilidad de las reacciones para la disociación del Na₂SiF₆ y formación del Si₃N₄, sino también una vez que se han formado las especies SiF_x por la primera reacción, la segunda reacción es incluso más factible. El Si₃N₄ amorfo se obtiene a temperaturas de hasta 1173 K mientras que el Si₃N₄ cristalino α y β se forman en el rango de temperaturas de 1273–1573 K y con tiempos de procesamiento tan cortos como 120 minutos. Se determinaron las condiciones óptimas para maximizar la formación del Si₃N₄.

Descriptores: Termodinámica; CVD; Si₃N₄amorfo; Si₃N₄α y β; precursores gas–sólido.

 

PACS: 81.15.Gh; 81.20.Ka; 82.60.–s

 

DESCARGAR ARTÍCULO EN FORMATO PDF

 

Acknowledgements

Authors express their gratitude to Conacyt (National council of Science and Technology, México) for financial support under project No. CB–2005–1/24322. Dr. Leal–Cruz gratefully acknowledges Conacyt's assistance in providing a doctoral scholarship. Authors also wish to thank Mr. Felipe Marquez Torres for technical assistance during the characterization by scanning electron microscopy (SEM).

 

Referencias

1. F. Galasso, U. Kuntz, and W.J. Croft, J. Am. Ceram. Soc. 55 [8] (1972) 431.        [ Links ]

2. K.S. Mazdiyasni and C.M. Cooke, J.A. Ceram, Soc. 56 [12] (1973) 628.        [ Links ]

3. K. Hajime, S. Shinichi, and I. Takao,         [ Links ] Japan Patent No. JP58115008 (1983).

4. W.–C. Lee and S.–L. Chung, J. of Materials Research 12 [3] (1997) 805.        [ Links ]

5. K. Tang et al., Advanced Materials 11 [8] (1999) 653.        [ Links ]

6. A. de Pablos, J. Bermuda, and M.I. Osendi, J. Am. Ceram. Soc. 84 [5] (2001) 1033.        [ Links ]

7. Y.G. Cao et al., J. of Crystal Growth 234 (2002) 9.        [ Links ]

8. C. Dianying, Z. Baolin, Z. Hanrui, L. Wenlan, and X. Suying, Materials Research Bulletin 37 | (2002) 1481.        [ Links ]

9. H. Arik, J. of the Eur. Cer. Soc. 23 (2003) 2005.        [ Links ]

10. Y. Gu, L. Chen, and Y. Qian, J. Am. Ceram. Soc. 87 [9] (2004) 1810.        [ Links ]

11. I.G. Cano and M.A. Rodríguez, Scripta Materialia 50 (2004) 383.        [ Links ]

12. A.L. Leal–Cruz and M.I. Pech–Canul, Mater. Chem. and Phys. 98 (2006) 27.        [ Links ]

13. R.C.G. Swann, R.R. Mehta, and T.P Cauge, J. Electrochem. Soc.: Solid State Science. 114 [7] (1967) 713.        [ Links ]

14. E.A. Taft, J. Electrochem. Soc. 118 [8] (1971) 1341.        [ Links ]

15. A.K. Sinha, H.J. Levinstein, T.E. Smith, G. Quintana, and S. E. Haszko, J. Electrochem. Soc.: Solid–State Science and Technology 125 [4] (1973) 601.        [ Links ]

16. A.K. Sinha and T.E. Smith, J. Appl. Phys. 49 [5] (1978) 2756.        [ Links ]

17. H. Nakayama and T. Enomoto, Japanese J. of Appl. Phys. 18 [9] (1979) 1773.        [ Links ]

18. S. Fujita, M. Nishihara, W–L Hoi, and A. Sasaki, Japanese J. of Appl. Phys. 20 [5] (1981) 917.        [ Links ]

19. M. Maeada and Y. Arita, J. Appl. Phys. 53 [10] (1982) 6852.        [ Links ]

20. A.J. Lowe, M.J. Powell, and S.R. Elliot, J. Appl. Phys. 59 [4] (1986) 1251.        [ Links ]

21. Y Manabe and T. Mitsuyu, J. Appl. Phys. 66 [6] (1989) 2475.        [ Links ]

22. R.K. Pandey, L.S. Patil, J.P. Bange, and D.K. Gautam, Optical Materials 27 (2004) 139.        [ Links ]

23. W.E. Lee and W.M. Rainforth, Ceramic microstructures, property control by processing (Chapman & Hall, New York, 1994).        [ Links ]

24. K.L. Choy, Progress in Materials Science 48 (2003) 57.        [ Links ]

25. R.C. Weast, C.R.C. Handbook of Chemistry and Physics, 51 ed. (The Chemical Rubber Co., Cleveland OH, 1970).        [ Links ]

26. F.S. Galasso, R.D. Veltri, and W.J. Croft, Am. Ceram. Soc. Bull. 57 [4] (1978) 453.        [ Links ]

27. M. Vanka and J. Vachuska, Termochimica Acta 36 (1980) 387.        [ Links ]

28. P. Chiotti, Journal of Less–Common Metals 80 (1981) 105.        [ Links ]

29. Y Kashiwaya and A.W. Cramb, Metall. and Mater. Trans. 33B (2002) 129.        [ Links ]

30. A.L. Leal–Cruz and M.I. Pech–Canul, J. Solid State Ionics 177 (2007) 3529.        [ Links ]

31. R. Roy, A Primer on the Taguchi Method, Society of Manufacturing Engineers (Dearborn Michigan, 1990).        [ Links ]

32. F.S. Galasso, R.D. Veltri, and W.J. Croft, J. Amer. Ceram. Soc. 57 [4] (1978) 453.        [ Links ]

33. J.D. Wu et al.,Thin Solid Films 350 (1999) 101.        [ Links ]

34. M. Vila, C. Prieto, P. Miranzo, M.I. Osendi, and R. Ramírez, Surface and Coatings Tech. 151–152 (2002) 67.        [ Links ]

35. R.K. Pandey, L.S. Patil, Jaspal P. Bange, D.K., J. Optical Materials 27 (2004) 139.        [ Links ]

36. B.S. Sahu, P. Srivastava, O.P. Agnihotri, and S.M. Shivaprasad, J. of non–crystalline solids 351 (2005) 771.        [ Links ]

37. J.D. McDonald, C.H. Williams, J.C. Thompson, and J.L. Margrave, Advan. Chem. Ser. 72 (1968) 261.        [ Links ]