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. 1966 Jan-Feb;70A(1):11-16.
doi: 10.6028/jres.070A.003.

Phase Equilibria in the System Niobium Pentoxide- Boric Acid

Ernest M Levin

Phase Equilibria in the System Niobium Pentoxide- Boric Acid

Ernest M Levin. J Res Natl Bur Stand A Phys Chem. 1966 Jan-Feb.

Abstract

The phase-equilibrium diagram for the system Nb2O5-B2O3 was determined experimentally using the quenching technique and examining the samples by optical microscopy and x-ray powder diffractometry. The system contains one binary compound of approximate composition "3Nb2O5 · B2O3," which melts incongruently at about 1150 °C to H -Nb2O5 and B2O3-rich liquid. A large region of liquid immiscibility extends, at 1352 °C, from 10 mole percent Nb2O5 to 65.7 mole percent Nb2O5. The theoretically calculated extent of immiscibility is in reasonable agreement with the experimentally determined value.

Keywords: Boric oxide; immiscibility; niobium pentoxide; oxides; phase equilibria.

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Figures

Figure 1.
Figure 1.. Phase diagram for the system Nb2O5–B2O3.
● –No melting; ◐ –partial melting; ◯ –complete melting; ▼ – chemically analyzed value of mechanically separated phases in two liquid regions.
See this image and copyright information in PMC

References

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