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CaAcAlIr2

High-Entropy Materials HEA

MP-ID: mp-3247204 · Space group: Imm2 (#44)

Materials Project API

Basic Information

Formula
CaAcAlIr2
MP-ID
mp-3247204
Elements
4
Sites
5
Density
10.1030
g/cm³
Volume
111.52
ų
Cell a
5.8467
Å
Cell b
5.8467
Å
Cell c
5.8467
Å
α Angle
139.21
°
β Angle
118.90
°
γ Angle
76.09
°
Space Group
Imm2
Point Group
mm2
Crystal System
Orthorhombic
Bravais Lattice
oI
Stability
Yes
Packing Fraction
-

X-ray Diffraction

Diffraction Pattern
X-axis: 2θ (°); Y-axis: relative intensity; Cu Kα ; λ=1.5418 Å
Diffraction Peaks (Top 24)
2θd (Å)Ihkl
17.76 4.9937 52.3 (1,0,0)
19.28 4.6045 38.8 (1,1,-1)
23.88 3.7265 40.3 (0,1,0)
23.88 3.7265 40.3 (1,0,-1)
26.52 3.3609 35.1 (0,0,1)
30.07 2.9717 1.8 (1,-1,1)
32.84 2.7274 13.3 (2,1,-1)
32.84 2.7274 13.3 (1,2,-2)
33.00 2.7147 12.8 (1,1,0)
33.00 2.7147 25.7 (2,0,-1)
33.00 2.7147 12.8 (1,1,-2)
35.97 2.4968 95.6 (2,0,0)
36.65 2.4519 48.5 (1,2,-1)
36.65 2.4519 48.5 (2,1,-2)
38.76 2.3234 100.0 (1,0,1)
38.76 2.3234 33.3 (0,1,-2)
39.13 2.3023 28.0 (2,2,-2)
44.46 2.0375 37.1 (1,-1,-1)
46.91 1.9368 4.4 (2,-1,1)
47.89 1.8994 4.5 (2,2,-1)
47.89 1.8994 2.2 (3,1,-2)
47.89 1.8994 2.2 (2,2,-3)
48.11 1.8912 5.2 (2,1,0)
48.11 1.8912 5.2 (3,0,-1)
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Energy Properties

Formation Energy/atom
-0.75802
eV/atom
Energy/atom
-38.18334
eV/atom
Energy above Hull
0.0000
eV/atom
Uncorrected Energy
-38.1833
eV/atom
Volume/atom
22.30
ų
c/a Ratio
1.0000

Electronic Properties

Metallic
Metal
Band Gap
0
eV
Direct Gap
No
CBM
N/A
eV

Magnetic Properties

Magnetic
No
Total Mag. Moment
0.0000
μB
Mag. Ordering
NM
Mag. Sites
0
Magnetization/Volume
0.000000
μB/ų

Elastic Properties

Elastic data not available

Feature Analysis

Composition Overview

Element Composition (atomic fraction)
Composition Info
Major / Matrix Element
Ir · 0.400
Element Family
5d-TM
Solute Fraction
0.600
Interstitial Fraction
0.000

High-Entropy Alloy Features

Composite Radar (normalized)
Element-Class Share
Mix Entropy ΔS/R
1.3322
HEA criterion (>1.0 = high entropy)
Mix Entropy ΔS
11.0757
J/mol·K
Ω Parameter
1.0513
Ω > 1.1 favors solid solution
Atomic Size Mismatch δr
17.579%
δr < 6.6% favors single-phase solid solution
Electronegativity Diff Δχ
0.5153
smaller = more stable mixing
VEC
5.000
valence electron concentration, affects phase stability
Mix Enthalpy ΔH_mix
-18.646
kJ/mol; negative = exothermic mixing
Entropy Norm
0.9610
SS Former
0
Phase Tendency
AM

Related Tasks

Related computation task IDs (1)
aaahctom

Citation & References

Materials Project Page
https://materialsproject.org/materials/mp-3247204
Reference Citation

The crystal structure and related material properties of CaAcAlIr2 were obtained from the Materials Project database (MP-ID: mp-3247204, 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…

Style: Ball & Stick
Raw CIF Data 
# generated using pymatgen
data_CaAcAlIr2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.84669984
_cell_length_b   5.84670014
_cell_length_c   5.84669896
_cell_angle_alpha   139.20990223
_cell_angle_beta   118.90356278
_cell_angle_gamma   76.08719663
_symmetry_Int_Tables_number   1
_chemical_formula_structural   CaAcAlIr2
_chemical_formula_sum   'Ca1 Ac1 Al1 Ir2'
_cell_volume   111.51838831
_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
  Ca  Ca0  1  0.30227504  0.80227404  0.49999900  1.0
  Ac  Ac1  1  0.69441092  0.19441092  0.50000000  1.0
  Al  Al2  1  0.00253957  0.00253957  1.00000000  1.0
  Ir  Ir3  1  0.74842364  0.50038674  0.24803691  1.0
  Ir  Ir4  1  0.25234983  0.50038574  0.75196309  1.0
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