Rb5(CoO2)2

High-Entropy Materials HEA Traditional Materials TRA

MP-ID: mp-795772 · Space group: P-1 (#2)

Materials Project API

Basic Information

Formula

Rb5(CoO2)2

MP-ID

mp-795772

Elements

Sites

Density

3.8310

g/cm³

Volume

528.12

Å³

Cell a

7.0614

Cell b

9.3232

Cell c

9.7255

α Angle

118.06

β Angle

89.67

γ Angle

108.44

Space Group

P-1

Point Group

-1

Crystal System

Triclinic

Bravais Lattice

Stability

Packing Fraction

X-ray Diffraction

Diffraction Pattern

Target / Radiation

X-axis: 2θ (°); Y-axis: relative intensity; Cu Kα ; λ=1.5418 Å

Diffraction Peaks (Top 24)

2θ	d (Å)	I	hkl
11.09	7.9800	31.6	(0,1,-1)
15.55	5.7002	91.1	(1,-1,1)
15.56	5.6964	1.3	(1,0,-1)
18.28	4.8526	2.4	(0,1,-2)
19.15	4.6353	20.4	(1,1,-1)
19.63	4.5217	1.3	(1,-1,-1)
20.61	4.3085	2.6	(1,1,0)
21.01	4.2282	2.7	(0,0,2)
22.28	3.9900	66.0	(0,2,-2)
22.43	3.9634	16.1	(1,-1,2)
22.96	3.8736	6.8	(1,0,-2)
23.13	3.8451	28.1	(0,2,0)
23.54	3.7795	17.0	(1,-2,2)
25.30	3.5197	3.3	(2,-1,0)
26.92	3.3125	41.5	(1,0,2)
27.01	3.3012	4.0	(2,-1,1)
27.28	3.2693	23.4	(2,0,-1)
27.65	3.2261	36.3	(1,2,-1)
28.12	3.1736	97.2	(2,-2,1)
28.34	3.1494	100.0	(1,-2,-1)
28.56	3.1257	3.4	(0,2,-3)
29.30	3.0477	8.7	(1,-3,1)
29.65	3.0129	13.0	(1,-3,2)
30.40	2.9403	1.9	(1,-2,3)

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Energy Properties

Formation Energy/atom

1.82044

eV/atom

Energy/atom

-1.72150

eV/atom

Energy above Hull

3.1010

eV/atom

Uncorrected Energy

-1.1739

eV/atom

Volume/atom

24.01

Å³

c/a Ratio

1.3773

Electronic Properties

Metallic

Metal

Band Gap

Direct Gap

CBM

N/A

Magnetic Properties

Magnetic

Yes

Total Mag. Moment

9.6401

μB

Mag. Ordering

Mag. Sites

Magnetization/Volume

0.018250

μB/Å³

Elastic Properties

Elastic data not available

Feature Analysis

Composition Overview

Element Composition (atomic fraction)

Composition Info

Major / Matrix Element

Rb · 0.455

Element Family

Alkali-AlkEarth

Solute Fraction

0.545

Interstitial Fraction

0.000

High-Entropy Alloy Features

Composite Radar (normalized)

Element-Class Share

Mix Entropy ΔS/R

1.0362

HEA criterion (>1.0 = high entropy)

Mix Entropy ΔS

8.6150

J/mol·K

Ω Parameter

0.0000

Ω > 1.1 favors solid solution

Atomic Size Mismatch δr

52.610%

δr < 6.6% favors single-phase solid solution

Electronegativity Diff Δχ

1.1783

smaller = more stable mixing

VEC

3.545

valence electron concentration, affects phase stability

Mix Enthalpy ΔH_mix

0.000

kJ/mol; negative = exothermic mixing

Entropy Norm

0.9432

SS Former

Phase Tendency

Traditional Material Features

ROM Blended-Feature Radar

Rating & Classification

Tier

Score

0.240

Family

Rb-rich Multi-Component

Matrix Element

Rb · 0.455

Related Tasks

Related computation task IDs (2)

aaabtheq aaabwdjm

Citation & References

Materials Project Page

https://materialsproject.org/materials/mp-795772

Reference Citation

The crystal structure and related material properties of Rb5(CoO2)2 were obtained from the Materials Project database (MP-ID: mp-795772, database version v2026.04.13).

Literature Citation

Horton, M.K., Huck, P., Yang, R.X. et al. Accelerated data-driven materials science with the Materials Project. Nat. Mater. 24, 1522–1532 (2025). https://doi.org/10.1038/s41563-025-02272-0

3D Crystal Structure Rendering

Loading 3D structure…

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Raw CIF Data

# generated using pymatgen
data_Rb5(CoO2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.06137700
_cell_length_b   9.32316657
_cell_length_c   9.72549129
_cell_angle_alpha   118.05706487
_cell_angle_beta   89.66912512
_cell_angle_gamma   108.44379706
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Rb5(CoO2)2
_chemical_formula_sum   'Rb10 Co4 O8'
_cell_volume   528.12251702
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Rb  Rb0  1  0.09669000  0.38819600  0.22168100  1.0
  Rb  Rb1  1  0.90331000  0.61180400  0.77831900  1.0
  Rb  Rb2  1  0.09778700  0.99333400  0.22224500  1.0
  Rb  Rb3  1  0.90221300  0.00666600  0.77775500  1.0
  Rb  Rb4  1  0.27009700  0.09814000  0.97564200  1.0
  Rb  Rb5  1  0.72990300  0.90186000  0.02435800  1.0
  Rb  Rb6  1  0.61885300  0.62937500  0.36339600  1.0
  Rb  Rb7  1  0.38114700  0.37062500  0.63660400  1.0
  Rb  Rb8  1  0.37825200  0.93395700  0.61599300  1.0
  Rb  Rb9  1  0.62174800  0.06604300  0.38400700  1.0
  Co  Co10  1  0.40001600  0.63468500  0.97394900  1.0
  Co  Co11  1  0.59998400  0.36531500  0.02605100  1.0
  Co  Co12  1  0.01539500  0.63643300  0.57748600  1.0
  Co  Co13  1  0.98460500  0.36356700  0.42251400  1.0
  O  O14  1  0.31081600  0.82305200  0.95469000  1.0
  O  O15  1  0.68918400  0.17694800  0.04531000  1.0
  O  O16  1  0.77094600  0.16588900  0.52090100  1.0
  O  O17  1  0.22905400  0.83411100  0.47909900  1.0
  O  O18  1  0.68248900  0.54631100  0.04737300  1.0
  O  O19  1  0.31751100  0.45368900  0.95262700  1.0
  O  O20  1  0.18921100  0.57371700  0.31445500  1.0
  O  O21  1  0.81078900  0.42628300  0.68554500  1.0

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