RbMg6CoO8

High-Entropy Materials HEA

MP-ID: mp-1032333 · Space group: P4/mmm (#123)

Materials Project API

Basic Information

Formula

RbMg6CoO8

MP-ID

mp-1032333

Elements

Sites

Density

3.9304

g/cm³

Volume

176.69

Å³

Cell a

9.0564

Cell b

4.4171

Cell c

4.4171

α Angle

90.00

β Angle

90.00

γ Angle

90.00

Space Group

P4/mmm

Point Group

4/mmm

Crystal System

Tetragonal

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
9.77	9.0564	48.3	(1,0,0)
19.60	4.5282	18.9	(2,0,0)
20.10	4.4171	1.9	(0,1,0)
22.39	3.9700	1.7	(1,1,0)
28.22	3.1619	2.1	(2,1,0)
28.58	3.1233	13.7	(0,1,1)
29.59	3.0188	15.2	(3,0,0)
30.27	2.9527	25.3	(1,1,1)
34.90	2.5711	48.8	(2,1,1)
36.04	2.4923	2.4	(3,1,0)
39.81	2.2641	49.7	(4,0,0)
40.86	2.2085	100.0	(0,2,0)
41.61	2.1706	7.3	(3,1,1)
42.11	2.1457	6.2	(1,2,0)
45.71	1.9850	8.0	(2,2,0)
49.74	1.8331	5.7	(4,1,1)
51.25	1.7825	11.8	(3,2,0)
55.60	1.6529	1.3	(3,2,1)
58.37	1.5810	56.6	(4,2,0)
58.95	1.5669	5.3	(5,1,1)
59.16	1.5617	29.4	(0,2,2)
60.12	1.5390	2.1	(1,2,2)
61.43	1.5094	1.4	(6,0,0)
62.96	1.4763	2.9	(2,2,2)

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Energy Properties

Formation Energy/atom

-2.24948

eV/atom

Energy/atom

-5.84201

eV/atom

Energy above Hull

0.3867

eV/atom

Uncorrected Energy

-5.3961

eV/atom

Volume/atom

11.04

Å³

c/a Ratio

0.4877

Electronic Properties

Metallic

Metal

Band Gap

Direct Gap

CBM

N/A

Magnetic Properties

Magnetic

Yes

Total Mag. Moment

2.6667

μB

Mag. Ordering

Mag. Sites

Magnetization/Volume

0.015090

μB/Å³

Elastic Properties

Elastic data not available

Feature Analysis

Composition Overview

Element Composition (atomic fraction)

Composition Info

Major / Matrix Element

O · 0.500

Element Family

Metalloid-Nonmetal

Solute Fraction

0.500

Interstitial Fraction

0.000

High-Entropy Alloy Features

Composite Radar (normalized)

Element-Class Share

Mix Entropy ΔS/R

1.0610

HEA criterion (>1.0 = high entropy)

Mix Entropy ΔS

8.8208

J/mol·K

Ω Parameter

1.5850

Ω > 1.1 favors solid solution

Atomic Size Mismatch δr

50.062%

δr < 6.6% favors single-phase solid solution

Electronegativity Diff Δχ

1.0765

smaller = more stable mixing

VEC

3.375

valence electron concentration, affects phase stability

Mix Enthalpy ΔH_mix

-2.802

kJ/mol; negative = exothermic mixing

Entropy Norm

0.7653

SS Former

Phase Tendency

Related Tasks

Related computation task IDs (2)

aaacgtdd aaacgtfy

Citation & References

Materials Project Page

https://materialsproject.org/materials/mp-1032333

Reference Citation

The crystal structure and related material properties of RbMg6CoO8 were obtained from the Materials Project database (MP-ID: mp-1032333, 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

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Raw CIF Data

# generated using pymatgen
data_RbMg6CoO8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.05642871
_cell_length_b   4.41706245
_cell_length_c   4.41706245
_cell_angle_alpha   90.00000000
_cell_angle_beta   90.00000000
_cell_angle_gamma   90.00000000
_symmetry_Int_Tables_number   1
_chemical_formula_structural   RbMg6CoO8
_chemical_formula_sum   'Rb1 Mg6 Co1 O8'
_cell_volume   176.69491518
_cell_formula_units_Z   1
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  0.00000000  0.50000000  0.50000000  1.0
  Mg  Mg1  1  0.50000000  0.00000000  0.00000000  1.0
  Mg  Mg2  1  0.50000000  0.50000000  0.50000000  1.0
  Mg  Mg3  1  0.26697655  0.00000000  0.50000000  1.0
  Mg  Mg4  1  0.73302345  0.00000000  0.50000000  1.0
  Mg  Mg5  1  0.26697655  0.50000000  0.00000000  1.0
  Mg  Mg6  1  0.73302345  0.50000000  0.00000000  1.0
  Co  Co7  1  0.00000000  0.00000000  0.00000000  1.0
  O  O8  1  0.25428556  0.00000000  0.00000000  1.0
  O  O9  1  0.74571444  0.00000000  0.00000000  1.0
  O  O10  1  0.28042398  0.50000000  0.50000000  1.0
  O  O11  1  0.71957602  0.50000000  0.50000000  1.0
  O  O12  1  0.00000000  0.00000000  0.50000000  1.0
  O  O13  1  0.50000000  0.00000000  0.50000000  1.0
  O  O14  1  0.00000000  0.50000000  0.00000000  1.0
  O  O15  1  0.50000000  0.50000000  0.00000000  1.0

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