Ca7Mg(CoO3)8

High-Entropy Materials HEA

MP-ID: mp-1076128 · Space group: Pm-3m (#221)

Materials Project API

Basic Information

Formula

Ca7Mg(CoO3)8

MP-ID

mp-1076128

Elements

Sites

Density

4.4806

g/cm³

Volume

430.02

Å³

Cell a

7.5480

Cell b

7.5480

Cell c

7.5480

α Angle

90.00

β Angle

90.00

γ Angle

90.00

Space Group

Pm-3m

Point Group

m-3m

Crystal System

Cubic

Bravais Lattice

Stability

Packing Fraction

0.5236

X-ray Diffraction

Diffraction Pattern

Target / Radiation

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

Diffraction Peaks (Top 9)

2θ	d (Å)	I	hkl
23.57	3.7740	26.6	(2,0,0)
33.58	2.6686	100.0	(2,2,0)
41.44	2.1789	3.2	(2,2,2)
48.23	1.8870	50.4	(4,0,0)
54.36	1.6878	8.8	(4,2,0)
60.05	1.5407	35.0	(4,2,2)
70.59	1.3343	26.6	(4,4,0)
75.59	1.2580	3.5	(4,4,2)
80.48	1.1934	14.4	(6,2,0)

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Energy Properties

Formation Energy/atom

-1.84178

eV/atom

Energy/atom

-6.62899

eV/atom

Energy above Hull

0.1863

eV/atom

Uncorrected Energy

-5.8892

eV/atom

Volume/atom

10.75

Å³

c/a Ratio

1.0000

Electronic Properties

Metallic

Metal

Band Gap

Direct Gap

CBM

N/A

Magnetic Properties

Magnetic

Yes

Total Mag. Moment

10.9365

μB

Mag. Ordering

Mag. Sites

Magnetization/Volume

0.025430

μB/Å³

Elastic Properties

Elastic data not available

Feature Analysis

Composition Overview

Element Composition (atomic fraction)

Composition Info

Major / Matrix Element

O · 0.600

Element Family

Metalloid-Nonmetal

Solute Fraction

0.400

Interstitial Fraction

0.000

High-Entropy Alloy Features

Composite Radar (normalized)

Element-Class Share

Mix Entropy ΔS/R

1.0256

HEA criterion (>1.0 = high entropy)

Mix Entropy ΔS

8.5270

J/mol·K

Ω Parameter

2.4373

Ω > 1.1 favors solid solution

Atomic Size Mismatch δr

53.396%

δr < 6.6% favors single-phase solid solution

Electronegativity Diff Δχ

1.0072

smaller = more stable mixing

VEC

4.600

valence electron concentration, affects phase stability

Mix Enthalpy ΔH_mix

-2.116

kJ/mol; negative = exothermic mixing

Entropy Norm

0.7398

SS Former

Phase Tendency

Related Tasks

Related computation task IDs (2)

aaacjfyi aaadzibp

Citation & References

Materials Project Page

https://materialsproject.org/materials/mp-1076128

Reference Citation

The crystal structure and related material properties of Ca7Mg(CoO3)8 were obtained from the Materials Project database (MP-ID: mp-1076128, 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_Ca7Mg(CoO3)8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.54794700
_cell_length_b   7.54794700
_cell_length_c   7.54794700
_cell_angle_alpha   90.00000000
_cell_angle_beta   90.00000000
_cell_angle_gamma   90.00000000
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ca7Mg(CoO3)8
_chemical_formula_sum   'Ca7 Mg1 Co8 O24'
_cell_volume   430.01789206
_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
  Ca  Ca0  1  0.50000000  0.00000000  0.50000000  1.0
  Ca  Ca1  1  0.50000000  0.00000000  0.00000000  1.0
  Ca  Ca2  1  0.50000000  0.50000000  0.00000000  1.0
  Ca  Ca3  1  0.00000000  0.00000000  0.50000000  1.0
  Ca  Ca4  1  0.00000000  0.00000000  0.00000000  1.0
  Ca  Ca5  1  0.00000000  0.50000000  0.50000000  1.0
  Ca  Ca6  1  0.00000000  0.50000000  0.00000000  1.0
  Mg  Mg7  1  0.50000000  0.50000000  0.50000000  1.0
  Co  Co8  1  0.25029200  0.74970800  0.25029200  1.0
  Co  Co9  1  0.25029200  0.74970800  0.74970800  1.0
  Co  Co10  1  0.25029200  0.25029200  0.25029200  1.0
  Co  Co11  1  0.25029200  0.25029200  0.74970800  1.0
  Co  Co12  1  0.74970800  0.74970800  0.25029200  1.0
  Co  Co13  1  0.74970800  0.74970800  0.74970800  1.0
  Co  Co14  1  0.74970800  0.25029200  0.25029200  1.0
  Co  Co15  1  0.74970800  0.25029200  0.74970800  1.0
  O  O16  1  0.50000000  0.74918900  0.25081100  1.0
  O  O17  1  0.50000000  0.74918900  0.74918900  1.0
  O  O18  1  0.50000000  0.25081100  0.25081100  1.0
  O  O19  1  0.50000000  0.25081100  0.74918900  1.0
  O  O20  1  0.00000000  0.75003900  0.24996100  1.0
  O  O21  1  0.00000000  0.75003900  0.75003900  1.0
  O  O22  1  0.00000000  0.24996100  0.24996100  1.0
  O  O23  1  0.00000000  0.24996100  0.75003900  1.0
  O  O24  1  0.24996100  0.00000000  0.24996100  1.0
  O  O25  1  0.24996100  0.00000000  0.75003900  1.0
  O  O26  1  0.25081100  0.50000000  0.25081100  1.0
  O  O27  1  0.25081100  0.50000000  0.74918900  1.0
  O  O28  1  0.75003900  0.00000000  0.24996100  1.0
  O  O29  1  0.75003900  0.00000000  0.75003900  1.0
  O  O30  1  0.74918900  0.50000000  0.25081100  1.0
  O  O31  1  0.74918900  0.50000000  0.74918900  1.0
  O  O32  1  0.25081100  0.74918900  0.50000000  1.0
  O  O33  1  0.24996100  0.75003900  0.00000000  1.0
  O  O34  1  0.25081100  0.25081100  0.50000000  1.0
  O  O35  1  0.24996100  0.24996100  0.00000000  1.0
  O  O36  1  0.74918900  0.74918900  0.50000000  1.0
  O  O37  1  0.75003900  0.75003900  0.00000000  1.0
  O  O38  1  0.74918900  0.25081100  0.50000000  1.0
  O  O39  1  0.75003900  0.24996100  0.00000000  1.0

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