Co(NiO2)2

High-Entropy Materials HEA Traditional Materials TRA

MP-ID: mp-863417 · Space group: P2_1/c (#14)

Materials Project API

Basic Information

Formula

Co(NiO2)2

MP-ID

mp-863417

Elements

Sites

Density

5.6745

g/cm³

Volume

281.30

Å³

Cell a

5.8761

Cell b

5.0405

Cell c

10.5927

α Angle

63.72

β Angle

90.00

γ Angle

90.00

Space Group

P2_1/c

Point Group

2/m

Crystal System

Monoclinic

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
18.69	4.7488	39.2	(0,0,2)
19.64	4.5193	12.4	(0,1,0)
20.26	4.3837	26.6	(0,1,2)
31.88	2.8068	9.9	(2,0,1)
32.86	2.7260	38.3	(0,1,-2)
34.00	2.6370	34.1	(0,1,4)
35.37	2.5379	100.0	(2,1,1)
35.65	2.5185	49.5	(0,2,2)
35.94	2.4985	1.7	(2,0,2)
37.89	2.3744	15.4	(0,0,4)
39.97	2.2557	28.4	(2,1,-1)
41.19	2.1918	14.8	(0,2,4)
41.95	2.1535	43.4	(2,0,3)
48.85	1.8645	4.4	(2,2,3)
50.74	1.7993	1.1	(0,1,-4)
51.95	1.7603	17.4	(0,2,-2)
52.27	1.7501	45.2	(2,1,-3)
53.32	1.7180	37.5	(2,1,5)
54.05	1.6968	23.5	(0,2,6)
55.44	1.6574	22.5	(2,2,-1)
55.97	1.6430	1.2	(0,3,4)
56.95	1.6169	15.2	(2,2,5)
57.80	1.5952	1.4	(2,0,5)
61.56	1.5064	9.3	(0,3,0)

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Energy Properties

Formation Energy/atom

-1.07082

eV/atom

Energy/atom

-6.56875

eV/atom

Energy above Hull

0.0902

eV/atom

Uncorrected Energy

-5.2162

eV/atom

Volume/atom

10.05

Å³

c/a Ratio

1.8027

Electronic Properties

Metallic

Metal

Band Gap

Direct Gap

CBM

N/A

Magnetic Properties

Magnetic

Yes

Total Mag. Moment

19.9990

μB

Mag. Ordering

Mag. Sites

Magnetization/Volume

0.071100

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

0.0000

Ω > 1.1 favors solid solution

Atomic Size Mismatch δr

36.357%

δr < 6.6% favors single-phase solid solution

Electronegativity Diff Δχ

0.7622

smaller = more stable mixing

VEC

6.429

valence electron concentration, affects phase stability

Mix Enthalpy ΔH_mix

0.000

kJ/mol; negative = exothermic mixing

Entropy Norm

0.8699

SS Former

Phase Tendency

Traditional Material Features

ROM Blended-Feature Radar

Rating & Classification

Tier

Score

0.502

Family

O-rich Multi-Component

Matrix Element

O · 0.571

Related Tasks

Related computation task IDs (2)

aaabzcpd aaaefloy

Citation & References

Materials Project Page

https://materialsproject.org/materials/mp-863417

Reference Citation

The crystal structure and related material properties of Co(NiO2)2 were obtained from the Materials Project database (MP-ID: mp-863417, 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_Co(NiO2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.87605700
_cell_length_b   5.04046000
_cell_length_c   10.59271718
_cell_angle_alpha   63.71585995
_cell_angle_beta   90.00000000
_cell_angle_gamma   90.00000000
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Co(NiO2)2
_chemical_formula_sum   'Co4 Ni8 O16'
_cell_volume   281.29801252
_cell_formula_units_Z   4
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
  Co  Co0  1  0.35728900  0.20550000  0.02852700  1.0
  Co  Co1  1  0.85728900  0.79450000  0.47147300  1.0
  Co  Co2  1  0.14271100  0.20550000  0.52852700  1.0
  Co  Co3  1  0.64271100  0.79450000  0.97147300  1.0
  Ni  Ni4  1  0.36973200  0.78199700  0.47041600  1.0
  Ni  Ni5  1  0.88020200  0.49215300  0.75179300  1.0
  Ni  Ni6  1  0.86973200  0.21800300  0.02958400  1.0
  Ni  Ni7  1  0.38020200  0.50784700  0.74820700  1.0
  Ni  Ni8  1  0.61979800  0.49215300  0.25179300  1.0
  Ni  Ni9  1  0.13026800  0.78199700  0.97041600  1.0
  Ni  Ni10  1  0.11979800  0.50784700  0.24820700  1.0
  Ni  Ni11  1  0.63026800  0.21800300  0.52958400  1.0
  O  O12  1  0.63287100  0.05081700  0.37540100  1.0
  O  O13  1  0.37810000  0.47666600  0.11307500  1.0
  O  O14  1  0.13268400  0.49754100  0.88726800  1.0
  O  O15  1  0.11077400  0.06271700  0.38473300  1.0
  O  O16  1  0.61077400  0.93728300  0.11526700  1.0
  O  O17  1  0.63268400  0.50245900  0.61273200  1.0
  O  O18  1  0.87810000  0.52333400  0.38692500  1.0
  O  O19  1  0.13287100  0.94918300  0.12459900  1.0
  O  O20  1  0.86712900  0.05081700  0.87540100  1.0
  O  O21  1  0.12190000  0.47666600  0.61307500  1.0
  O  O22  1  0.36731600  0.49754100  0.38726800  1.0
  O  O23  1  0.38922600  0.06271700  0.88473300  1.0
  O  O24  1  0.88922600  0.93728300  0.61526700  1.0
  O  O25  1  0.86731600  0.50245900  0.11273200  1.0
  O  O26  1  0.62190000  0.52333400  0.88692500  1.0
  O  O27  1  0.36712900  0.94918300  0.62459900  1.0

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