Ac2(Si2Pd7)3

High-Entropy Materials HEA Traditional Materials TRA

MP-ID: mp-3292723 · Space group: Fm-3m (#225)

Materials Project API

Basic Information

Formula

Ac2(Si2Pd7)3

MP-ID

mp-3292723

Elements

Sites

Density

10.1836

g/cm³

Volume

465.92

Å³

Cell a

8.7018

Cell b

8.7018

Cell c

8.7018

α Angle

120.00

β Angle

90.00

γ Angle

120.00

Space Group

Fm-3m

Point Group

m-3m

Crystal System

Cubic

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
14.40	6.1531	5.0	(1,-1,1)
20.41	4.3509	3.5	(2,-1,0)
32.54	2.7517	48.7	(3,-1,-1)
35.74	2.5120	45.7	(3,-1,1)
37.99	2.3683	100.0	(3,-2,2)
41.51	2.1754	36.9	(4,-2,0)
43.51	2.0801	27.6	(4,-2,1)
44.16	2.0510	4.1	(3,0,-3)
46.68	1.9458	1.8	(4,-1,-2)
46.68	1.9458	3.6	(3,-2,3)
48.51	1.8767	1.4	(4,-1,1)
49.11	1.8552	21.2	(4,-2,2)
53.15	1.7232	1.2	(4,-3,3)
55.91	1.6445	2.7	(5,-2,1)
60.15	1.5383	6.1	(4,-4,4)
61.70	1.5034	1.3	(5,-2,2)
62.21	1.4923	16.3	(5,-1,-3)
64.22	1.4503	37.6	(6,-3,0)
65.71	1.4210	12.9	(6,-3,1)
66.20	1.4116	3.4	(6,-2,0)
69.60	1.3508	7.1	(5,-4,4)
71.98	1.3118	1.9	(6,-1,0)
73.40	1.2900	3.3	(6,-4,3)
75.73	1.2560	21.9	(6,-2,2)

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Energy Properties

Formation Energy/atom

-0.71930

eV/atom

Energy/atom

-23.89472

eV/atom

Energy above Hull

0.0000

eV/atom

Uncorrected Energy

-23.8947

eV/atom

Volume/atom

16.07

Å³

c/a Ratio

1.0000

Electronic Properties

Metallic

Metal

Band Gap

Direct Gap

CBM

N/A

Magnetic Properties

Magnetic

Total Mag. Moment

0.0026

μB

Mag. Ordering

Mag. Sites

Magnetization/Volume

0.000010

μB/Å³

Elastic Properties

Elastic data not available

Feature Analysis

Composition Overview

Element Composition (atomic fraction)

Composition Info

Major / Matrix Element

Pd · 0.724

Element Family

4d-TM

Solute Fraction

0.276

Interstitial Fraction

0.207

High-Entropy Alloy Features

Composite Radar (normalized)

Element-Class Share

Mix Entropy ΔS/R

0.7441

HEA criterion (>1.0 = high entropy)

Mix Entropy ΔS

6.1867

J/mol·K

Ω Parameter

1.0082

Ω > 1.1 favors solid solution

Atomic Size Mismatch δr

12.963%

δr < 6.6% favors single-phase solid solution

Electronegativity Diff Δχ

0.2882

smaller = more stable mixing

VEC

8.207

valence electron concentration, affects phase stability

Mix Enthalpy ΔH_mix

-10.825

kJ/mol; negative = exothermic mixing

Entropy Norm

0.6773

SS Former

Phase Tendency

Traditional Material Features

ROM Blended-Feature Radar

Rating & Classification

Tier

Score

0.650

Family

Interstitial Alloy

Matrix Element

Pd · 0.724

Related Tasks

Related computation task IDs (1)

aaahfixf

Citation & References

Materials Project Page

https://materialsproject.org/materials/mp-3292723

Reference Citation

The crystal structure and related material properties of Ac2(Si2Pd7)3 were obtained from the Materials Project database (MP-ID: mp-3292723, 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_Ac2(Si2Pd7)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.70177215
_cell_length_b   8.70177194
_cell_length_c   8.70177215
_cell_angle_alpha   120.00000079
_cell_angle_beta   90.00000000
_cell_angle_gamma   120.00000079
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ac2(Si2Pd7)3
_chemical_formula_sum   'Ac2 Si6 Pd21'
_cell_volume   465.91651373
_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  0.75000000  0.50000000  0.25000000  1.0
  Ac  Ac1  1  0.25000000  0.50000000  0.75000000  1.0
  Si  Si2  1  0.26327737  0.00000000  0.26327737  1.0
  Si  Si3  1  0.73672263  0.00000000  0.26327737  1.0
  Si  Si4  1  0.26327737  0.52655374  0.26327737  1.0
  Si  Si5  1  0.73672263  0.00000000  0.73672263  1.0
  Si  Si6  1  0.26327737  0.00000000  0.73672263  1.0
  Si  Si7  1  0.73672263  0.47344626  0.73672263  1.0
  Pd  Pd8  1  0.00000000  0.00000000  0.00000000  1.0
  Pd  Pd9  1  0.34413376  0.00000000  0.00000000  1.0
  Pd  Pd10  1  0.65586624  0.00000000  0.00000000  1.0
  Pd  Pd11  1  0.00000000  0.34413376  0.00000000  1.0
  Pd  Pd12  1  0.34413376  0.34413376  0.00000000  1.0
  Pd  Pd13  1  1.00000000  0.65586624  1.00000000  1.0
  Pd  Pd14  1  0.65586624  0.65586624  1.00000000  1.0
  Pd  Pd15  1  0.38725398  0.77450897  0.16176195  1.0
  Pd  Pd16  1  0.00000000  0.00000000  0.34413376  1.0
  Pd  Pd17  1  0.00000000  0.34413376  0.34413376  1.0
  Pd  Pd18  1  0.34413376  0.34413376  0.34413376  1.0
  Pd  Pd19  1  0.61274602  0.22549103  0.38725398  1.0
  Pd  Pd20  1  0.16176195  0.77450897  0.38725398  1.0
  Pd  Pd21  1  0.61274602  0.77450897  0.38725398  1.0
  Pd  Pd22  1  0.38725398  0.22549103  0.61274602  1.0
  Pd  Pd23  1  0.83823805  0.22549103  0.61274602  1.0
  Pd  Pd24  1  0.38725398  0.77450897  0.61274602  1.0
  Pd  Pd25  1  0.00000000  0.00000000  0.65586624  1.0
  Pd  Pd26  1  1.00000000  0.65586624  0.65586624  1.0
  Pd  Pd27  1  0.65586624  0.65586624  0.65586624  1.0
  Pd  Pd28  1  0.61274602  0.22549103  0.83823805  1.0

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