AcAl9Co2

High-Entropy Materials HEA Traditional Materials TRA

MP-ID: mp-3294360 · Space group: P6/mmm (#191)

Materials Project API

Basic Information

Formula

AcAl9Co2

MP-ID

mp-3294360

Elements

Sites

Density

4.6970

g/cm³

Volume

207.77

Å³

Cell a

7.8034

Cell b

7.8034

Cell c

3.9399

α Angle

90.00

β Angle

90.00

γ Angle

120.00

Space Group

P6/mmm

Point Group

6/mmm

Crystal System

Hexagonal

Bravais Lattice

Stability

Yes

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
13.10	6.7579	22.5	(1,0,-1,0)
13.10	6.7579	11.3	(1,-1,0,0)
22.57	3.9399	25.0	(0,0,0,1)
22.79	3.9017	100.0	(2,-1,-1,0)
26.18	3.4037	36.4	(1,0,-1,1)
26.38	3.3790	22.8	(2,0,-2,0)
32.29	2.7723	97.6	(2,-1,-1,1)
34.98	2.5649	66.3	(2,0,-2,1)
35.13	2.5543	24.2	(3,-1,-2,0)
35.13	2.5543	12.1	(2,-3,1,0)
40.03	2.2526	4.8	(3,0,-3,0)
40.03	2.2526	9.5	(3,-3,0,0)
42.16	2.1433	1.4	(3,-1,-2,1)
46.08	1.9700	19.0	(0,0,0,2)
46.43	1.9556	51.4	(3,0,-3,1)
46.55	1.9508	33.0	(4,-2,-2,0)
48.11	1.8912	3.6	(1,0,-1,2)
48.57	1.8743	1.9	(4,-1,-3,0)
52.00	1.7585	21.8	(2,-1,-1,2)
52.33	1.7483	36.2	(4,-2,-2,1)
53.87	1.7019	6.9	(2,0,-2,2)
54.19	1.6926	15.2	(4,-1,-3,1)
54.30	1.6895	9.4	(4,0,-4,0)
59.23	1.5599	17.0	(3,-1,-2,2)

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Energy Properties

Formation Energy/atom

-0.42762

eV/atom

Energy/atom

-13.40219

eV/atom

Energy above Hull

0.0000

eV/atom

Uncorrected Energy

-13.4022

eV/atom

Volume/atom

17.31

Å³

c/a Ratio

0.5049

Electronic Properties

Metallic

Metal

Band Gap

Direct Gap

CBM

N/A

Magnetic Properties

Magnetic

Total Mag. Moment

0.0001

μB

Mag. Ordering

Mag. Sites

Magnetization/Volume

0.000000

μB/Å³

Elastic Properties

Elastic data not available

Feature Analysis

Composition Overview

Element Composition (atomic fraction)

Composition Info

Major / Matrix Element

Al · 0.750

Element Family

PostTransition-Noble

Solute Fraction

0.250

Interstitial Fraction

0.000

High-Entropy Alloy Features

Composite Radar (normalized)

Element-Class Share

Mix Entropy ΔS/R

0.7215

HEA criterion (>1.0 = high entropy)

Mix Entropy ΔS

5.9982

J/mol·K

Ω Parameter

0.6977

Ω > 1.1 favors solid solution

Atomic Size Mismatch δr

11.543%

δr < 6.6% favors single-phase solid solution

Electronegativity Diff Δχ

0.1839

smaller = more stable mixing

VEC

3.917

valence electron concentration, affects phase stability

Mix Enthalpy ΔH_mix

-9.500

kJ/mol; negative = exothermic mixing

Entropy Norm

0.6567

SS Former

Phase Tendency

Traditional Material Features

ROM Blended-Feature Radar

Rating & Classification

Tier

Score

0.807

Family

Al-based Alloy

Matrix Element

Al · 0.750

Related Tasks

Related computation task IDs (1)

aaahflie

Citation & References

Materials Project Page

https://materialsproject.org/materials/mp-3294360

Reference Citation

The crystal structure and related material properties of AcAl9Co2 were obtained from the Materials Project database (MP-ID: mp-3294360, 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_AcAl9Co2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.80336881
_cell_length_b   7.80336850
_cell_length_c   3.93991734
_cell_angle_alpha   90.00000000
_cell_angle_beta   90.00000000
_cell_angle_gamma   119.99999716
_symmetry_Int_Tables_number   1
_chemical_formula_structural   AcAl9Co2
_chemical_formula_sum   'Ac1 Al9 Co2'
_cell_volume   207.76960039
_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
  Ac  Ac0  1  0.00000000  0.00000000  0.00000000  1.0
  Al  Al1  1  0.78490540  0.56980980  0.50000000  1.0
  Al  Al2  1  0.21509460  0.78490540  0.50000000  1.0
  Al  Al3  1  0.56980980  0.78490540  0.50000000  1.0
  Al  Al4  1  0.50000000  0.00000000  0.00000000  1.0
  Al  Al5  1  0.50000000  0.50000000  0.00000000  1.0
  Al  Al6  1  0.00000000  0.50000000  0.00000000  1.0
  Al  Al7  1  0.21509460  0.43019020  0.50000000  1.0
  Al  Al8  1  0.78490540  0.21509460  0.50000000  1.0
  Al  Al9  1  0.43019020  0.21509460  0.50000000  1.0
  Co  Co10  1  0.66666700  0.33333300  0.00000000  1.0
  Co  Co11  1  0.33333300  0.66666700  0.00000000  1.0

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