RbMg6CoO8
High-Entropy Materials HEAMP-ID: mp-1032377 · Space group: P4/mmm (#123)
Basic Information
Formula
RbMg6CoO8
MP-ID
mp-1032377
Elements
4
Sites
16
Density
3.8362
g/cm³
Volume
181.03
ų
Cell a
8.6659
Å
Cell b
4.5706
Å
Cell c
4.5706
Å
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
tP
Stability
No
Packing Fraction
-
X-ray Diffraction
Diffraction Pattern
X-axis: 2θ (°); Y-axis: relative intensity; Cu Kα ; λ=1.5418 Å
Diffraction Peaks (Top 24)
| 2θ | d (Å) | I | hkl |
|---|---|---|---|
| 19.42 | 4.5706 | 31.2 | (0,1,0) |
| 20.50 | 4.3330 | 15.0 | (2,0,0) |
| 21.99 | 4.0427 | 1.3 | (1,1,0) |
| 27.60 | 3.2319 | 13.4 | (0,1,1) |
| 28.38 | 3.1445 | 26.8 | (2,1,0) |
| 29.50 | 3.0282 | 1.1 | (1,1,1) |
| 30.96 | 2.8886 | 2.0 | (3,0,0) |
| 34.62 | 2.5906 | 46.0 | (2,1,1) |
| 36.81 | 2.4418 | 2.5 | (3,1,0) |
| 39.43 | 2.2853 | 100.0 | (0,2,0) |
| 41.69 | 2.1665 | 39.3 | (4,0,0) |
| 44.32 | 2.0440 | 7.1 | (0,2,1) |
| 44.84 | 2.0214 | 7.4 | (2,2,0) |
| 46.38 | 1.9577 | 4.8 | (4,1,0) |
| 49.29 | 1.8487 | 10.9 | (2,2,1) |
| 50.73 | 1.7996 | 3.8 | (4,1,1) |
| 50.95 | 1.7922 | 1.8 | (3,2,0) |
| 55.04 | 1.6685 | 1.4 | (3,2,1) |
| 56.99 | 1.6159 | 29.9 | (0,2,2) |
| 58.72 | 1.5723 | 50.7 | (4,2,0) |
| 60.80 | 1.5235 | 1.3 | (0,3,0) |
| 61.22 | 1.5141 | 2.8 | (2,2,2) |
| 62.47 | 1.4868 | 4.0 | (4,2,1) |
| 64.47 | 1.4453 | 2.2 | (0,3,1) |
Energy Properties
Formation Energy/atom
-2.23609
eV/atom
Energy/atom
-5.82862
eV/atom
Energy above Hull
0.4001
eV/atom
Uncorrected Energy
-5.3827
eV/atom
Volume/atom
11.31
ų
c/a Ratio
0.5274
Electronic Properties
Metallic
Metal
Band Gap
0
eV
Direct Gap
No
CBM
N/A
eV
Magnetic Properties
Magnetic
Yes
Total Mag. Moment
3.5294
μB
Mag. Ordering
FM
Mag. Sites
1
Magnetization/Volume
0.019500
μB/ų
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
0
Phase Tendency
IM
Related Tasks
Citation & References
Materials Project Page
https://materialsproject.org/materials/mp-1032377
Reference Citation
The crystal structure and related material properties of RbMg6CoO8 were obtained from the Materials Project database (MP-ID: mp-1032377, 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 8.66592234
_cell_length_b 4.57056960
_cell_length_c 4.57056960
_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 181.03204033
_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 0.50000000 0.00000000 -0.00000000 1.0
Mg Mg1 1 -0.00000000 0.50000000 0.50000000 1.0
Mg Mg2 1 0.50000000 0.50000000 0.50000000 1.0
Mg Mg3 1 0.24205262 0.00000000 0.50000000 1.0
Mg Mg4 1 0.75794738 -0.00000000 0.50000000 1.0
Mg Mg5 1 0.24205262 0.50000000 0.00000000 1.0
Mg Mg6 1 0.75794738 0.50000000 -0.00000000 1.0
Co Co7 1 -0.00000000 0.00000000 -0.00000000 1.0
O O8 1 0.21384199 -0.00000000 0.00000000 1.0
O O9 1 0.78615801 0.00000000 -0.00000000 1.0
O O10 1 0.24802917 0.50000000 0.50000000 1.0
O O11 1 0.75197083 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
