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Updated: Dec 26, 2025
08:23
Niobium Oxide Films Deposited by Reactive Sputtering: Effect of Oxygen Flow Rate
Published on: September 28, 2019
7.7K
Temperature-Pressure Phase Relationships in Niobium Pentoxide.
J L Waring1, R S Roth1, H S Parker1
1Institute for Materials Research, National Bureau of Standards, Washington, D.C. 20234.
Summary
Researchers mapped the phase equilibrium diagram for niobium pentoxide (Nb2O5) under varying pressure and temperature. This study characterized four distinct phases, including detailed structural analysis of L-Nb2O5.
Area of Science:
- Materials Science
- Solid-State Chemistry
- Crystallography
Background:
- Niobium pentoxide (Nb2O5) exhibits complex phase behavior critical for its applications.
- Understanding the pressure-temperature (P-T) phase diagram is essential for controlling its structural properties.
Purpose of the Study:
- To determine a pressure-temperature (P-T) section of the Nb2O5 phase equilibrium diagram.
- To characterize the single-phase regions within this diagram.
- To elucidate the superstructure of the L-Nb2O5 phase.
Main Methods:
- X-ray powder diffraction (XRD) was employed to identify and characterize single-phase regions.
- Single crystal electron diffraction was used to confirm structural details.
- Indexing of the L-Nb2O5 superstructure was performed based on comparisons with L-Ta2O5.
Main Results:
- Four single-phase regions were identified: H-Nb2O5, B-Nb2O5, and two distinct L-Nb2O5 regions.
- The superstructure of L-Nb2O5 was determined to be orthorhombic.
- The unit cell parameters for L-Nb2O5 were established as a = 6.168 Å, b = 29.312 Å, c = 3.938 Å, with the b-axis being 8 times the subcell length.
Conclusions:
- The study successfully mapped a P-T section of the Nb2O5 phase diagram.
- The structural characterization of L-Nb2O5 provides crucial crystallographic data.
- This work contributes to a fundamental understanding of Nb2O5 polymorphism.
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