H. Zhang et al. / Journal of Alloys and Compounds 484 (2009) 352–355
355
absorber of Na for unpressed sample which facilitates the decom-
[4] Y. Nakamori, K. Miwa, A. Ninomiya, H. Li, N. Ohba, S. Towata, A. Züttel, S. Orimo,
Phys. Rev. B 74 (2006) 045126.
position of NaH to an absorber of Na O for pressed samples which
2
[
5] Y.H. Shang, R. Chen, Energy Fuels 20 (2006) 2149.
[6] T. Czujko, R.A. Varin, Z. Wronski, Z. Zaranski, T. Durejko, J. Alloys Compd. 427
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facilitates the formation of NaBH4.
(
[
[
[
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4
. Conclusions
The present work proposes a synthesis route for the prepara-
[
[
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tion of NaBH4 based on a solid-state reaction, i.e., by calcining
the 4NaH–NaBO –2SiO2 ternary mixture. It is found that NaBH4 is
2
Compd. 427 (2005) 404.
successfully synthesized under Ar, instead of H2 atmosphere. The
pressure applied to the reactant pellet is of crucial for the reaction
pathway: for unpressed samples, NaH decomposes to H2 and Na;
for the pressed samples, the reaction route changes gradually to
the formation of NaBH4 with the increase of the pressing pressure.
When the pressing pressure is elevated from 10 MPa to 30 MPa, the
yield for NaBH4 is increased from 8% to 32%. A higher yield can be
expected with a further increase in the pressure. Moreover, the role
of SiO2 changes from the absorber of Na for the unpressed samples
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[
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4
to the absorber of Na O for the pressed samples.
2
[
[
Acknowledgments
1
[
This work was supported by the National Natural Science Foun-
dation of China (Nos. 10776004, 20833009) and the Shanghai
Leading Academic Discipline Project (No. B113).
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[
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