FeCo3O8

High-Entropy Materials HEA Traditional Materials TRA

MP-ID: mp-761579 · Space group: P6_3mc (#186)

Materials Project API

Basic Information

Formula

FeCo3O8

MP-ID

mp-761579

Elements

Sites

Density

4.9279

g/cm³

Volume

243.05

Å³

Cell a

5.6135

Cell b

5.6135

Cell c

8.9063

α Angle

90.00

β Angle

90.00

γ Angle

120.00

Space Group

P6_3mc

Point Group

6mm

Crystal System

Hexagonal

Bravais Lattice

Stability

Packing Fraction

0.7405

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
19.94	4.4532	82.3	(0,0,0,2)
20.82	4.2671	100.0	(1,0,-1,1)
27.16	3.2837	33.5	(1,0,-1,2)
35.43	2.5337	32.6	(1,0,-1,3)
36.98	2.4307	16.8	(2,0,-2,0)
37.89	2.3745	49.8	(2,-1,-1,2)
38.39	2.3450	19.5	(2,-2,0,1)
38.39	2.3449	39.1	(2,0,-2,1)
40.51	2.2266	6.2	(0,0,0,4)
42.36	2.1336	12.9	(2,-2,0,2)
42.36	2.1336	25.9	(2,0,-2,2)
44.77	2.0244	1.1	(1,0,-1,4)
48.40	1.8807	18.3	(2,-2,0,3)
48.40	1.8807	36.5	(2,0,-2,3)
50.73	1.7996	7.7	(3,-1,-2,1)
52.46	1.7444	2.7	(2,-1,-1,4)
52.46	1.7444	1.4	(1,1,-2,4)
53.99	1.6985	10.2	(3,-1,-2,2)
56.01	1.6419	7.0	(2,-2,0,4)
56.01	1.6419	14.0	(2,0,-2,4)
59.13	1.5624	12.6	(3,-1,-2,3)
59.13	1.5624	6.3	(2,1,-3,3)
60.83	1.5228	3.8	(3,-3,0,2)
60.83	1.5228	7.6	(3,0,-3,2)

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Energy Properties

Formation Energy/atom

-1.07785

eV/atom

Energy/atom

-6.86568

eV/atom

Energy above Hull

0.0821

eV/atom

Uncorrected Energy

-5.8102

eV/atom

Volume/atom

10.13

Å³

c/a Ratio

1.5866

Electronic Properties

Metallic

Metal

Band Gap

Direct Gap

CBM

N/A

Magnetic Properties

Magnetic

Yes

Total Mag. Moment

14.0001

μB

Mag. Ordering

Mag. Sites

Magnetization/Volume

0.057600

μB/Å³

Elastic Properties

Elastic data not available

Feature Analysis

Composition Overview

Element Composition (atomic fraction)

Composition Info

Major / Matrix Element

O · 0.667

Element Family

Metalloid-Nonmetal

Solute Fraction

0.333

Interstitial Fraction

0.000

High-Entropy Alloy Features

Composite Radar (normalized)

Element-Class Share

Mix Entropy ΔS/R

0.8240

HEA criterion (>1.0 = high entropy)

Mix Entropy ΔS

6.8504

J/mol·K

Ω Parameter

51.7440

Ω > 1.1 favors solid solution

Atomic Size Mismatch δr

37.627%

δr < 6.6% favors single-phase solid solution

Electronegativity Diff Δχ

0.7414

smaller = more stable mixing

VEC

5.583

valence electron concentration, affects phase stability

Mix Enthalpy ΔH_mix

-0.083

kJ/mol; negative = exothermic mixing

Entropy Norm

0.7500

SS Former

Phase Tendency

Traditional Material Features

ROM Blended-Feature Radar

Rating & Classification

Tier

Score

0.565

Family

O-rich Multi-Component

Matrix Element

O · 0.667

Related Tasks

Related computation task IDs (2)

aaabyqjp aaaegbxv

Citation & References

Materials Project Page

https://materialsproject.org/materials/mp-761579

Reference Citation

The crystal structure and related material properties of FeCo3O8 were obtained from the Materials Project database (MP-ID: mp-761579, 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_FeCo3O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.61348062
_cell_length_b   5.61348062
_cell_length_c   8.90632000
_cell_angle_alpha   90.00000000
_cell_angle_beta   90.00000000
_cell_angle_gamma   120.00000731
_symmetry_Int_Tables_number   1
_chemical_formula_structural   FeCo3O8
_chemical_formula_sum   'Fe2 Co6 O16'
_cell_volume   243.04872663
_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
  Fe  Fe0  1  0.33333300  0.66666700  0.49571100  1.0
  Fe  Fe1  1  0.66666700  0.33333300  0.99571100  1.0
  Co  Co2  1  0.16779600  0.83220400  0.21214500  1.0
  Co  Co3  1  0.16779600  0.33559200  0.21214500  1.0
  Co  Co4  1  0.66440800  0.83220400  0.21214500  1.0
  Co  Co5  1  0.33559200  0.16779600  0.71214500  1.0
  Co  Co6  1  0.83220400  0.66440800  0.71214500  1.0
  Co  Co7  1  0.83220400  0.16779600  0.71214500  1.0
  O  O8  1  0.16012800  0.83987200  0.60557100  1.0
  O  O9  1  0.03913100  0.51956500  0.32977800  1.0
  O  O10  1  0.33333300  0.66666700  0.10046400  1.0
  O  O11  1  0.00000000  0.00000000  0.31907100  1.0
  O  O12  1  0.00000000  0.00000000  0.81907100  1.0
  O  O13  1  0.16012800  0.32025700  0.60557100  1.0
  O  O14  1  0.48043500  0.96086900  0.32977800  1.0
  O  O15  1  0.48043500  0.51956500  0.32977800  1.0
  O  O16  1  0.32025700  0.16012800  0.10557100  1.0
  O  O17  1  0.67974300  0.83987200  0.60557100  1.0
  O  O18  1  0.51956500  0.48043500  0.82977800  1.0
  O  O19  1  0.51956500  0.03913100  0.82977800  1.0
  O  O20  1  0.66666700  0.33333300  0.60046400  1.0
  O  O21  1  0.83987200  0.67974300  0.10557100  1.0
  O  O22  1  0.96086900  0.48043500  0.82977800  1.0
  O  O23  1  0.83987200  0.16012800  0.10557100  1.0

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