Ca(CoO2)2

High-Entropy Materials HEA Traditional Materials TRA

MP-ID: mp-1048946 · Space group: R3m (#160)

Materials Project API

Basic Information

Formula

Ca(CoO2)2

MP-ID

mp-1048946

Elements

Sites

Density

4.3055

g/cm³

Volume

171.20

Å³

Cell a

6.3683

Cell b

6.3683

Cell c

6.3683

α Angle

57.28

β Angle

57.28

γ Angle

57.28

Space Group

R3m

Point Group

Crystal System

Trigonal

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
16.72	5.3039	78.2	(1,1,1)
17.68	5.0174	17.0	(1,0,0)
20.17	4.4034	2.6	(1,1,0)
20.17	4.4034	5.1	(1,0,1)
28.07	3.1787	40.6	(2,1,1)
28.07	3.1787	20.3	(1,1,2)
29.26	3.0525	9.1	(1,-1,0)
29.26	3.0525	18.1	(1,0,-1)
32.85	2.7265	82.9	(2,2,1)
33.80	2.6519	5.8	(2,2,2)
33.88	2.6457	90.4	(2,1,0)
33.88	2.6456	45.2	(1,0,2)
34.39	2.6078	100.0	(1,1,-1)
35.79	2.5087	27.3	(2,0,0)
40.99	2.2017	27.3	(2,2,0)
40.99	2.2017	54.6	(2,0,2)
43.33	2.0883	5.0	(3,2,2)
43.33	2.0883	2.5	(2,2,3)
45.30	2.0020	8.1	(3,2,1)
48.93	1.8616	6.7	(3,3,2)
51.15	1.7857	16.7	(3,1,0)
51.70	1.7680	5.3	(3,3,3)
51.88	1.7624	2.9	(2,-1,-1)
51.88	1.7624	1.4	(1,1,-2)

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Energy Properties

Formation Energy/atom

-1.71607

eV/atom

Energy/atom

-6.86811

eV/atom

Energy above Hull

0.1625

eV/atom

Uncorrected Energy

-6.0075

eV/atom

Volume/atom

12.23

Å³

c/a Ratio

1.0000

Electronic Properties

Metallic

Metal

Band Gap

Direct Gap

CBM

N/A

Magnetic Properties

Magnetic

Yes

Total Mag. Moment

4.0001

μB

Mag. Ordering

Mag. Sites

Magnetization/Volume

0.023370

μB/Å³

Elastic Properties

Elastic data not available

Feature Analysis

Composition Overview

Element Composition (atomic fraction)

Composition Info

Major / Matrix Element

O · 0.571

Element Family

Metalloid-Nonmetal

Solute Fraction

0.429

Interstitial Fraction

0.000

High-Entropy Alloy Features

Composite Radar (normalized)

Element-Class Share

Mix Entropy ΔS/R

0.9557

HEA criterion (>1.0 = high entropy)

Mix Entropy ΔS

7.9457

J/mol·K

Ω Parameter

3.0530

Ω > 1.1 favors solid solution

Atomic Size Mismatch δr

50.265%

δr < 6.6% favors single-phase solid solution

Electronegativity Diff Δχ

0.9565

smaller = more stable mixing

VEC

5.143

valence electron concentration, affects phase stability

Mix Enthalpy ΔH_mix

-1.811

kJ/mol; negative = exothermic mixing

Entropy Norm

0.8699

SS Former

Phase Tendency

Traditional Material Features

ROM Blended-Feature Radar

Rating & Classification

Tier

Score

0.454

Family

O-rich Multi-Component

Matrix Element

O · 0.571

Related Tasks

Related computation task IDs (3)

aaachrss aaaduyif aaaeabav

Citation & References

Materials Project Page

https://materialsproject.org/materials/mp-1048946

Reference Citation

The crystal structure and related material properties of Ca(CoO2)2 were obtained from the Materials Project database (MP-ID: mp-1048946, 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_Ca(CoO2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.36827020
_cell_length_b   6.36827020
_cell_length_c   6.36826937
_cell_angle_alpha   57.28361409
_cell_angle_beta   57.28361409
_cell_angle_gamma   57.28361323
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ca(CoO2)2
_chemical_formula_sum   'Ca2 Co4 O8'
_cell_volume   171.19850334
_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
  Ca  Ca0  1  0.00169900  0.00169900  0.00169900  1.0
  Ca  Ca1  1  0.62580200  0.62580200  0.62580200  1.0
  Co  Co2  1  0.23502700  0.23502700  0.23502700  1.0
  Co  Co3  1  0.62714400  0.62714400  0.12130300  1.0
  Co  Co4  1  0.12130300  0.62714400  0.62714400  1.0
  Co  Co5  1  0.62714400  0.12130300  0.62714400  1.0
  O  O6  1  0.36896100  0.84175200  0.36896100  1.0
  O  O7  1  0.84175200  0.36896100  0.36896100  1.0
  O  O8  1  0.36896100  0.36896100  0.84175200  1.0
  O  O9  1  0.38167800  0.38167800  0.38167800  1.0
  O  O10  1  0.86188400  0.86188400  0.86188400  1.0
  O  O11  1  0.87904900  0.87904900  0.43054800  1.0
  O  O12  1  0.43054800  0.87904900  0.87904900  1.0
  O  O13  1  0.87904900  0.43054800  0.87904900  1.0

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