Cs2O

cesium oxide · dicesium oxide

Cesium oxide is a stable semiconducting binary compound formed from cesium and oxygen.

CsO
Crystal structure of Cs2O (trigonal, R-3m (No. 166))
Ground-state structure · Materials Project
Overview

About cesium oxide

Cesium oxide is a binary inorganic compound composed of cesium and oxygen. As a thermodynamically stable material located on the convex hull, it represents a well-defined phase within the alkali metal oxide family, characterized by its distinct semiconducting electronic nature.

With extensive documentation across multiple structural databases, this compound is a significant subject of study for understanding alkali metal bonding and coordination chemistry. Its stable configuration makes it a primary reference point for researchers investigating the fundamental properties of heavy alkali oxides.

At a glance

Key Properties

Cross-validated computational properties for cesium oxide, aggregated across 3 databases.

Band Gap

0.27–1.92 eV
Range across DFT structures

Energy Above Hull

0.000 eV/atom
Best (lowest) across sources

Stability

On hull (stable)
2 DFT sources

Structures

70
3 databases, 13 space groups
Crystallography

Reported Structures

Lowest-energy structures reported for Cs2O, ranked by energy above hull.

Space GroupCrystal SystemBand Gap (eV)E above hull (eV/atom)E/atom (eV)Density (g/cm³)
R-3m (No. 166)trigonal0.580.0000-3.4354.58
Pnma (No. 62)orthorhombic1.920.0570-3.3785.06
Pnnm (No. 58)orthorhombic0.270.0583-3.3774.75
Imm2 (No. 44)Orthorhombic2.23
R-3m (No. 166)Trigonal4.15
Pnnm (No. 58)Orthorhombic4.36
P-1 (No. 2)Triclinic1.87
P-1 (No. 2)Triclinic2.03
R3m (No. 160)Trigonal3.68
Pnnm (No. 58)Orthorhombic4.45
C2/m (No. 12)Monoclinic2.64
P2/m (No. 10)Monoclinic2.50
Synthesis

Synthesis Routes

Literature-extracted synthesis procedures targeting Cs2O.

Sol-Gel
Procedure available · ceder_solid_state
Sol-Gel
Procedure available · ceder_solid_state
Uses

Applications

Where cesium oxide is used.

photocathode materialsspecialized optical coatingscatalysis research
Reference

Frequently Asked Questions

Common questions about cesium oxide, answered from cross-validated data.

What is Cs2O?

Cesium oxide is a stable semiconducting binary compound formed from cesium and oxygen.

More questions
What is Cs2O used for?
cesium oxide (Cs2O) is used in photocathode materials, specialized optical coatings, and catalysis research.
What is the band gap of Cs2O?
cesium oxide (Cs2O) has a DFT-computed band gap of 0.27–1.92 eV across 70 reported structures.
Is Cs2O a metal, semiconductor, or insulator?
With a band gap up to 1.92 eV it is a semiconductor.
Is Cs2O thermodynamically stable?
Yes — cesium oxide (Cs2O) sits on the convex hull (energy above hull 0 eV/atom), i.e. on hull (stable).
What is the crystal structure of Cs2O?
The lowest-energy reported polymorph of cesium oxide (Cs2O) is trigonal symmetry, space group R-3m (No. 166).
What is the density of Cs2O?
The computed density of the ground-state structure of cesium oxide (Cs2O) is 4.58 g/cm³.
How many polymorphs of Cs2O are known?
70 structures of Cs2O are reported across 3 databases, spanning 13 distinct space groups.
How is Cs2O synthesized?
Literature-reported routes for Cs2O include sol-gel (2 procedures documented).
What elements does Cs2O contain?
cesium oxide (Cs2O) contains Cs and O (2 elements).
Where does the data for Cs2O come from?
Cs2O data is cross-referenced from materials_project, mpaloe.
Comparison

How It Compares

As a foundational binary oxide, cesium oxide serves as a critical benchmark for evaluating the structural and electronic trends observed in the broader class of alkali metal oxides, providing essential insights into how cation size and electronegativity influence stability.

Data sources & attribution
  • materials_project — Data from the Materials Project. Cite: Jain et al., APL Materials 1, 011002 (2013).
  • mpaloe — Data from mpaloe.

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