AcAl8Fe2Si

High-Entropy Materials HEA

MP-ID: mp-3293597 · Space group: Cmmm (#65)

Materials Project API

Basic Information

Formula

AcAl8Fe2Si

MP-ID

mp-3293597

Elements

Sites

Density

4.7038

g/cm³

Volume

205.68

Å³

Cell a

7.8090

Cell b

7.7384

Cell c

3.9422

α Angle

90.00

β Angle

90.00

γ Angle

120.30

Space Group

Cmmm

Point Group

mmm

Crystal System

Orthorhombic

Bravais Lattice

Stability

Yes

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
13.13	6.7421	32.9	(1,-1,0)
13.25	6.6811	24.1	(0,1,0)
22.55	3.9422	39.3	(0,0,1)
22.78	3.9045	52.0	(2,-1,0)
22.99	3.8690	100.0	(1,-2,0)
26.19	3.4032	37.6	(1,-1,1)
26.25	3.3952	22.9	(0,1,1)
26.44	3.3711	27.8	(2,-2,0)
26.69	3.3406	11.0	(0,2,0)
32.27	2.7742	52.0	(2,-1,1)
32.42	2.7613	98.3	(1,-2,1)
35.02	2.5621	78.9	(2,-2,1)
35.12	2.5550	19.0	(3,-2,0)
35.21	2.5486	31.5	(0,2,1)
35.36	2.5383	17.9	(2,-3,0)
35.50	2.5285	22.8	(1,-3,0)
40.12	2.2474	7.4	(3,-3,0)
40.12	2.2474	7.4	(3,0,0)
40.51	2.2270	6.4	(0,3,0)
42.47	2.1283	2.1	(1,-3,1)
46.05	1.9711	30.3	(0,0,2)
46.51	1.9524	51.4	(3,-3,1)
46.52	1.9523	17.8	(4,-2,0)
46.85	1.9390	27.0	(0,3,1)

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Energy Properties

Formation Energy/atom

-0.32711

eV/atom

Energy/atom

-13.66835

eV/atom

Energy above Hull

0.0000

eV/atom

Uncorrected Energy

-13.6684

eV/atom

Volume/atom

17.14

Å³

c/a Ratio

0.5048

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 · 0.667

Element Family

PostTransition-Noble

Solute Fraction

0.333

Interstitial Fraction

0.083

High-Entropy Alloy Features

Composite Radar (normalized)

Element-Class Share

Mix Entropy ΔS/R

0.9831

HEA criterion (>1.0 = high entropy)

Mix Entropy ΔS

8.1734

J/mol·K

Ω Parameter

1.1153

Ω > 1.1 favors solid solution

Atomic Size Mismatch δr

12.751%

δr < 6.6% favors single-phase solid solution

Electronegativity Diff Δχ

0.1908

smaller = more stable mixing

VEC

3.833

valence electron concentration, affects phase stability

Mix Enthalpy ΔH_mix

-8.611

kJ/mol; negative = exothermic mixing

Entropy Norm

0.7091

SS Former

Phase Tendency

Related Tasks

Related computation task IDs (1)

aaahfkev

Citation & References

Materials Project Page

https://materialsproject.org/materials/mp-3293597

Reference Citation

The crystal structure and related material properties of AcAl8Fe2Si were obtained from the Materials Project database (MP-ID: mp-3293597, 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_AcAl8Fe2Si
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.80902977
_cell_length_b   7.73838572
_cell_length_c   3.94223549
_cell_angle_alpha   90.00000000
_cell_angle_beta   90.00000000
_cell_angle_gamma   120.30245276
_symmetry_Int_Tables_number   1
_chemical_formula_structural   AcAl8Fe2Si
_chemical_formula_sum   'Ac1 Al8 Fe2 Si1'
_cell_volume   205.67852897
_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  0.00000000  0.50000100  0.00000000  1.0
  Al  Al2  1  0.50000000  0.50000100  0.00000000  1.0
  Al  Al3  1  0.42692296  0.21235718  0.49999900  1.0
  Al  Al4  1  0.78543522  0.21235718  0.49999900  1.0
  Al  Al5  1  0.21775774  0.43551647  0.49999900  1.0
  Al  Al6  1  0.78224226  0.56448353  0.49999900  1.0
  Al  Al7  1  0.21456578  0.78764282  0.49999900  1.0
  Al  Al8  1  0.57307704  0.78764282  0.49999900  1.0
  Fe  Fe9  1  0.65997864  0.31995628  0.00000000  1.0
  Fe  Fe10  1  0.34002236  0.68004372  0.00000000  1.0
  Si  Si11  1  0.50000000  0.00000000  0.00000000  1.0

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