CaFe4O9

High-Entropy Materials HEA Traditional Materials TRA

MP-ID: mp-1048015 · Space group: P4/n (#85)

Materials Project API

Basic Information

Formula

CaFe4O9

MP-ID

mp-1048015

Elements

Sites

Density

3.5576

g/cm³

Volume

380.36

Å³

Cell a

8.3636

Cell b

8.3636

Cell c

5.4376

α Angle

90.00

β Angle

90.00

γ Angle

90.00

Space Group

P4/n

Point Group

4/m

Crystal System

Tetragonal

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
16.30	5.4376	61.5	(0,0,1)
19.47	4.5588	1.8	(1,0,1)
21.25	4.1818	2.5	(2,0,0)
22.21	4.0028	16.3	(1,1,1)
26.90	3.3149	7.1	(2,0,1)
28.97	3.0817	100.0	(2,1,1)
30.22	2.9570	6.1	(2,2,0)
32.94	2.7188	4.6	(0,0,2)
33.89	2.6448	43.2	(3,1,0)
34.53	2.5977	2.6	(2,2,1)
34.69	2.5856	6.6	(1,0,2)
37.83	2.3784	2.1	(3,1,1)
41.04	2.1992	27.6	(2,1,2)
42.36	2.1336	2.7	(3,2,1)
43.27	2.0909	1.1	(4,0,0)
45.31	2.0014	1.2	(2,2,2)
46.66	1.9465	6.4	(3,0,2)
47.86	1.9005	2.6	(4,1,1)
47.99	1.8958	3.6	(3,1,2)
48.69	1.8702	28.8	(4,2,0)
51.60	1.7714	1.4	(1,0,3)
51.69	1.7685	17.6	(4,2,1)
51.81	1.7647	6.3	(3,2,2)
52.83	1.7330	1.4	(1,1,3)

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Energy Properties

Formation Energy/atom

-1.44306

eV/atom

Energy/atom

-7.18716

eV/atom

Energy above Hull

0.2674

eV/atom

Uncorrected Energy

-6.1009

eV/atom

Volume/atom

13.58

Å³

c/a Ratio

0.6502

Electronic Properties

Metallic

Metal

Band Gap

Direct Gap

CBM

N/A

Magnetic Properties

Magnetic

Yes

Total Mag. Moment

31.9986

μB

Mag. Ordering

FiM

Mag. Sites

Magnetization/Volume

0.084130

μB/Å³

Elastic Properties

Elastic data not available

Feature Analysis

Composition Overview

Element Composition (atomic fraction)

Composition Info

Major / Matrix Element

O · 0.643

Element Family

Metalloid-Nonmetal

Solute Fraction

0.357

Interstitial Fraction

0.000

High-Entropy Alloy Features

Composite Radar (normalized)

Element-Class Share

Mix Entropy ΔS/R

0.8305

HEA criterion (>1.0 = high entropy)

Mix Entropy ΔS

6.9045

J/mol·K

Ω Parameter

2.6740

Ω > 1.1 favors solid solution

Atomic Size Mismatch δr

47.392%

δr < 6.6% favors single-phase solid solution

Electronegativity Diff Δχ

0.8738

smaller = more stable mixing

VEC

5.000

valence electron concentration, affects phase stability

Mix Enthalpy ΔH_mix

1.633

kJ/mol; negative = exothermic mixing

Entropy Norm

0.7559

SS Former

Phase Tendency

Traditional Material Features

ROM Blended-Feature Radar

Rating & Classification

Tier

Score

0.387

Family

O-rich Multi-Component

Matrix Element

O · 0.643

Related Tasks

Related computation task IDs (2)

aaachqkd aaaeasmt

Citation & References

Materials Project Page

https://materialsproject.org/materials/mp-1048015

Reference Citation

The crystal structure and related material properties of CaFe4O9 were obtained from the Materials Project database (MP-ID: mp-1048015, 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_CaFe4O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.36357500
_cell_length_b   8.36357500
_cell_length_c   5.43764000
_cell_angle_alpha   90.00000000
_cell_angle_beta   90.00000000
_cell_angle_gamma   90.00000000
_symmetry_Int_Tables_number   1
_chemical_formula_structural   CaFe4O9
_chemical_formula_sum   'Ca2 Fe8 O18'
_cell_volume   380.35958353
_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  0.50000000  0.00000000  0.83245700  1.0
  Ca  Ca1  1  0.00000000  0.50000000  0.16754300  1.0
  Fe  Fe2  1  0.21449000  0.90837100  0.37640400  1.0
  Fe  Fe3  1  0.90837100  0.78551000  0.62359600  1.0
  Fe  Fe4  1  0.40837100  0.28551000  0.37640400  1.0
  Fe  Fe5  1  0.71449000  0.40837100  0.62359600  1.0
  Fe  Fe6  1  0.78551000  0.09162900  0.37640400  1.0
  Fe  Fe7  1  0.59162900  0.71449000  0.37640400  1.0
  Fe  Fe8  1  0.28551000  0.59162900  0.62359600  1.0
  Fe  Fe9  1  0.09162900  0.21449000  0.62359600  1.0
  O  O10  1  0.00000000  0.00000000  0.50000000  1.0
  O  O11  1  0.50000000  0.50000000  0.50000000  1.0
  O  O12  1  0.07605400  0.26951200  0.94357700  1.0
  O  O13  1  0.23048800  0.57605400  0.94357700  1.0
  O  O14  1  0.76951200  0.42394600  0.94357700  1.0
  O  O15  1  0.92394600  0.73048800  0.94357700  1.0
  O  O16  1  0.42394600  0.23048800  0.05642300  1.0
  O  O17  1  0.26951200  0.92394600  0.05642300  1.0
  O  O18  1  0.73048800  0.07605400  0.05642300  1.0
  O  O19  1  0.57605400  0.76951200  0.05642300  1.0
  O  O20  1  0.70620200  0.89546900  0.53540900  1.0
  O  O21  1  0.60453100  0.20620200  0.53540900  1.0
  O  O22  1  0.39546900  0.79379800  0.53540900  1.0
  O  O23  1  0.29379800  0.10453100  0.53540900  1.0
  O  O24  1  0.20620200  0.39546900  0.46459100  1.0
  O  O25  1  0.89546900  0.29379800  0.46459100  1.0
  O  O26  1  0.10453100  0.70620200  0.46459100  1.0
  O  O27  1  0.79379800  0.60453100  0.46459100  1.0

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