Ac3SiS2

High-Entropy Materials HEA

MP-ID: mp-3249591 · Space group: Immm (#71)

Materials Project API

Basic Information

Formula

Ac3SiS2

MP-ID

mp-3249591

Elements

Sites

Density

6.9612

g/cm³

Volume

184.44

Å³

Cell a

7.6450

Cell b

7.6450

Cell c

7.6450

α Angle

146.04

β Angle

131.76

γ Angle

60.30

Space Group

Immm

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
24.50	3.6330	78.5	(1,-1,0)
24.72	3.6014	76.8	(2,1,-1)
28.45	3.1368	100.0	(1,2,-1)
28.57	3.1240	49.5	(1,-1,1)
40.40	2.2328	19.6	(1,-1,-1)
40.76	2.2135	76.5	(2,1,0)
40.96	2.2036	18.8	(3,3,-3)
47.94	1.8977	28.1	(0,3,-1)
48.21	1.8875	13.8	(2,-2,1)
48.31	1.8841	27.4	(3,3,-2)
48.34	1.8830	13.7	(3,0,0)
50.22	1.8165	21.1	(2,-2,0)
50.70	1.8007	20.5	(4,2,-2)
58.88	1.5684	6.6	(2,4,-2)
58.88	1.5684	6.6	(4,2,-4)
59.15	1.5620	6.5	(2,-2,2)
64.34	1.4480	6.0	(2,-2,-1)
64.76	1.4395	11.7	(1,2,-4)
65.07	1.4335	5.8	(4,2,-1)
65.07	1.4335	5.8	(1,5,-4)
65.24	1.4301	5.7	(5,4,-4)
66.27	1.4103	9.3	(0,3,0)
66.73	1.4017	13.6	(3,3,-1)
66.73	1.4017	4.5	(3,3,-5)

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Energy Properties

Formation Energy/atom

-1.81449

eV/atom

Energy/atom

-40.27354

eV/atom

Energy above Hull

0.0000

eV/atom

Uncorrected Energy

-40.2735

eV/atom

Volume/atom

30.74

Å³

c/a Ratio

1.0000

Electronic Properties

Metallic

Metal

Band Gap

Direct Gap

CBM

N/A

Magnetic Properties

Magnetic

Total Mag. Moment

0.0000

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

Ac · 0.500

Element Family

Actinide

Solute Fraction

0.500

Interstitial Fraction

0.167

High-Entropy Alloy Features

Composite Radar (normalized)

Element-Class Share

Mix Entropy ΔS/R

1.0114

HEA criterion (>1.0 = high entropy)

Mix Entropy ΔS

8.4088

J/mol·K

Ω Parameter

2.1132

Ω > 1.1 favors solid solution

Atomic Size Mismatch δr

29.019%

δr < 6.6% favors single-phase solid solution

Electronegativity Diff Δχ

0.6664

smaller = more stable mixing

VEC

3.667

valence electron concentration, affects phase stability

Mix Enthalpy ΔH_mix

-4.266

kJ/mol; negative = exothermic mixing

Entropy Norm

0.9206

SS Former

Phase Tendency

Related Tasks

Related computation task IDs (1)

aaahcxch

Citation & References

Materials Project Page

https://materialsproject.org/materials/mp-3249591

Reference Citation

The crystal structure and related material properties of Ac3SiS2 were obtained from the Materials Project database (MP-ID: mp-3249591, 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_Ac3SiS2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.64501690
_cell_length_b   7.64501685
_cell_length_c   7.64501651
_cell_angle_alpha   146.03727420
_cell_angle_beta   131.76298139
_cell_angle_gamma   60.30044848
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ac3SiS2
_chemical_formula_sum   'Ac3 Si1 S2'
_cell_volume   184.44412604
_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
  Ac  Ac1  1  0.66509362  0.66509362  1.00000000  1.0
  Ac  Ac2  1  0.33490638  0.33490638  0.00000000  1.0
  Si  Si3  1  0.50000000  0.00000000  0.50000000  1.0
  S  S4  1  0.16561418  0.66561418  0.50000000  1.0
  S  S5  1  0.83438582  0.33438582  0.50000000  1.0

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