NbO2

Niobium dioxide · Niobium(IV) oxide

Niobium dioxide is a stable, semiconducting refractory-metal oxide utilized primarily in electronic research and the development of advanced thin-film materials.

Crystal structure of NbO2 (tetragonal, I41/a (No. 88))
Ground-state structure · Materials Project
Overview

About Niobium dioxide

Niobium dioxide is a thermodynamically stable refractory-metal oxide that exhibits semiconducting behavior. It is a highly studied material due to its structural complexity and the diverse range of phases it can adopt, making it a subject of significant interest in materials science research. Beyond its fundamental physical properties, this compound is valued for its role in developing thin-film devices and electrochromic technologies. Its stability on the convex hull ensures it remains a reliable candidate for applications requiring robust chemical and thermal performance in electronic systems.

At a glance

Key Properties

Cross-validated computational properties for Niobium dioxide, aggregated across 5 databases.

Band Gap

0.04–0.47 eV
Range across DFT structures · ground state: small gap

Energy Above Hull

0.000 eV/atom
Best (lowest) across sources

Stability

Stable
3 DFT sources

Structures

434
5 databases, 41 space groups
Validation

Cross-Source DFT Agreement

How well independent DFT databases agree on the thermodynamics of NbO2. Tight agreement means computed properties can be trusted without re-running calculations.

Agreement Score

1.00 / 1.00
Trust tier: high

Hull Spread

0.000 eV
EAH spread across sources

Sources Compared

3
jarvis, materials_project, oqmd

Space Group Consensus

Mixed (most: I41/a (No. 88))
Crystallography

Reported Structures

Lowest-energy structures reported for NbO2, ranked by energy above hull.

Space GroupCrystal SystemBand Gap (eV)E above hull (eV/atom)E/atom (eV)Density (g/cm³)
——0.470.0000-2.719—
I41/a (No. 88)tetragonal0.280.0000-9.5635.75
P42/mnm (No. 136)tetragonal0.000.0000-2.621—
——0.000.0005-2.719—
I41/a (No. 88)tetragonal0.430.0024-9.5615.73
I41/amd (No. 141)tetragonal0.000.0265-2.595—
——0.000.0276-2.691—
——0.000.0276-2.691—
——0.000.0295-2.690—
P42/mnm (No. 136)tetragonal0.000.0475-9.5165.72
C2/m (No. 12)monoclinic0.000.0526-9.5114.98
——0.000.0628-2.656—
Uses

Applications

Where Niobium dioxide is used.

Electrochromic devicesResistive switching memoryThin-film electronicsCatalysis research
Intellectual Property

Patent Landscape

2 patents reference NbO2 or close compositional variants.

PatentTitleAssigneeGranted
10347471NbO2 sintered compact, sputtering target comprising the sintered compact, and method of producing NbO2 sintere——
4877504Methods for fabricating electro-optically active niobium dioxide (NbO.sub.2 )——
Reference

Frequently Asked Questions

Common questions about Niobium dioxide, answered from cross-validated data.

What is NbO2?

Niobium dioxide is a stable, semiconducting refractory-metal oxide utilized primarily in electronic research and the development of advanced thin-film materials.

More questions
What is NbO2 used for?
Niobium dioxide (NbO2) is used in electrochromic devices, resistive switching memory, thin-film electronics, and catalysis research.
What is the band gap of NbO2?
Niobium dioxide (NbO2) has a DFT-computed band gap of 0.04–0.47 eV across 434 reported structures. Standard DFT underestimates band gaps, so the measured gap is typically larger.
Is NbO2 a metal, semiconductor, or insulator?
DFT predicts a band gap of up to 0.47 eV (a semiconductor). Measured gaps are typically larger.
Is NbO2 thermodynamically stable?
Yes — Niobium dioxide (NbO2) sits on the convex hull (energy above hull 0 eV/atom), i.e. stable.
What is the crystal structure of NbO2?
The reference structure of Niobium dioxide (NbO2) is tetragonal symmetry, space group I41/a (No. 88).
What is the density of NbO2?
The computed density of the ground-state structure of Niobium dioxide (NbO2) is 5.75 g/cm³.
How many polymorphs of NbO2 are known?
434 structures of NbO2 are reported across 5 databases, spanning 41 distinct space groups.
What elements does NbO2 contain?
Niobium dioxide (NbO2) contains Nb and O (2 elements).
Where does the data for NbO2 come from?
NbO2 data is cross-referenced from oqmd, materials_project, jarvis.
Comparison

How It Compares

Within the electrochromic and refractory-metal oxides class.

Within the family of refractory-metal oxides, NbO2 serves as a critical counterpart to more common oxides like V2O5 and WO3. While V2O5 is widely recognized for its prominent electrochromic switching capabilities, NbO2 provides a distinct semiconducting profile that complements the broader Nb2O5 system, offering researchers a different electronic landscape for investigating metal-insulator transitions and resistive switching.

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Related Compounds

Other Electrochromic and Refractory-Metal Oxides in the database.

Data sources & attribution
  • oqmd — Data from the OQMD (oqmd.org). Cite: Saal et al., JOM 65, 1501 (2013); Kirklin et al., npj Comp. Mater. 1, 15010 (2015). (CC-BY-4.0)
  • materials_project — Data from the Materials Project (materialsproject.org). Cite: Jain et al., APL Materials 1, 011002 (2013). (CC-BY-4.0)
  • jarvis — Data from JARVIS (jarvis.nist.gov), NIST. Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020). (LicenseRef-US-Gov-PD)

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