66
J. Huang et al. / Thermochimica Acta 405 (2003) 61–66
when Na4FeO3 was heated for a short period of time.
It is in agreement with the experiment result given by
Sridharan.
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5. Conclusion
Vaporization behaviors of Na4FeO3(s) have been
investigated by a high temperature mass spec-
trometer from 590 to 717 K. It was found that
Na4FeO3(s) decomposed into Na3FeO3 and re-
leased sodium vapor. The temperature dependence
of partial vapor pressure of sodium was measured
to be ln PNa = 24.376–17749/T. According to the
present experiment, the Gibbs energy of formation
of Na3FeO3(s) was evaluated as, ꢀfG◦(Na3FeO3) =
−1168629 + 338.34 × T.
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Acknowledgements
The authors are indebted to S. Du, V. Stolyarova and
S. Seetharaman, KTH Sweden, for their early mass
spectrometric studies on sodium iron oxides. We thank
K. Okubo for his assistance in sample preparations and
operation of the X-ray powder diffraction equipment.
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