Ho4AlB4Ir9

High-Entropy Materials HEA

MP-ID: mp-3292196 · Space group: R-3m (#166)

Materials Project API

Basic Information

Formula

Ho4AlB4Ir9

MP-ID

mp-3292196

Elements

Sites

Density

15.3281

g/cm³

Volume

266.49

Å³

Cell a

10.7321

Cell b

10.7321

Cell c

10.7321

α Angle

29.57

β Angle

29.57

γ Angle

29.57

Space Group

R-3m

Point Group

-3m

Crystal System

Trigonal

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
8.62	10.2555	3.9	(1,1,1)
17.29	5.1278	2.5	(2,2,2)
19.58	4.5332	2.6	(1,1,0)
23.68	3.7570	2.3	(2,2,1)
26.07	3.4185	17.6	(3,3,3)
29.91	2.9874	2.7	(2,3,3)
29.91	2.9874	5.4	(3,3,2)
33.88	2.6461	2.6	(2,1,0)
34.75	2.5813	46.3	(4,3,3)
35.00	2.5639	8.1	(4,4,4)
37.22	2.4158	4.4	(3,2,1)
37.32	2.4094	29.1	(4,4,3)
38.05	2.3649	100.0	(1,1,-1)
38.40	2.3442	21.1	(2,0,0)
38.40	2.3442	10.6	(0,2,0)
39.77	2.2666	5.1	(2,2,0)
40.77	2.2132	7.6	(3,1,1)
42.28	2.1374	14.1	(3,2,4)
42.28	2.1374	28.2	(4,3,2)
44.15	2.0511	2.0	(5,5,5)
44.90	2.0188	2.9	(2,2,4)
44.90	2.0188	5.8	(4,2,2)
45.49	1.9940	1.2	(5,5,4)
48.46	1.8785	15.8	(4,4,2)

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Energy Properties

Formation Energy/atom

-0.92375

eV/atom

Energy/atom

-36.41692

eV/atom

Energy above Hull

0.0000

eV/atom

Uncorrected Energy

-36.4169

eV/atom

Volume/atom

14.80

Å³

c/a Ratio

1.0000

Electronic Properties

Metallic

Metal

Band Gap

Direct Gap

CBM

N/A

Magnetic Properties

Magnetic

Total Mag. Moment

0.0024

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

Ir · 0.500

Element Family

5d-TM

Solute Fraction

0.500

Interstitial Fraction

0.222

High-Entropy Alloy Features

Composite Radar (normalized)

Element-Class Share

Mix Entropy ΔS/R

1.1756

HEA criterion (>1.0 = high entropy)

Mix Entropy ΔS

9.7742

J/mol·K

Ω Parameter

2.4522

Ω > 1.1 favors solid solution

Atomic Size Mismatch δr

21.102%

δr < 6.6% favors single-phase solid solution

Electronegativity Diff Δχ

0.3918

smaller = more stable mixing

VEC

7.778

valence electron concentration, affects phase stability

Mix Enthalpy ΔH_mix

-9.282

kJ/mol; negative = exothermic mixing

Entropy Norm

0.8480

SS Former

Phase Tendency

Related Tasks

Related computation task IDs (1)

aaahficy

Citation & References

Materials Project Page

https://materialsproject.org/materials/mp-3292196

Reference Citation

The crystal structure and related material properties of Ho4AlB4Ir9 were obtained from the Materials Project database (MP-ID: mp-3292196, 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_Ho4AlB4Ir9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.73206174
_cell_length_b   10.73206145
_cell_length_c   10.73206242
_cell_angle_alpha   29.57093729
_cell_angle_beta   29.57093978
_cell_angle_gamma   29.57093899
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ho4AlB4Ir9
_chemical_formula_sum   'Ho4 Al1 B4 Ir9'
_cell_volume   266.48799319
_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
  Ho  Ho0  1  0.15014152  0.15014152  0.15014152  1.0
  Ho  Ho1  1  0.95001262  0.95001262  0.95001262  1.0
  Ho  Ho2  1  0.84985848  0.84985848  0.84985848  1.0
  Ho  Ho3  1  0.04998738  0.04998738  0.04998738  1.0
  Al  Al4  1  0.50000000  0.50000000  0.50000000  1.0
  B  B5  1  0.61560191  0.61560191  0.61560191  1.0
  B  B6  1  0.71783549  0.71783549  0.71783549  1.0
  B  B7  1  0.38439809  0.38439809  0.38439809  1.0
  B  B8  1  0.28216451  0.28216451  0.28216451  1.0
  Ir  Ir9  1  0.40103561  0.90167119  0.40103561  1.0
  Ir  Ir10  1  0.90167119  0.40103561  0.40103561  1.0
  Ir  Ir11  1  0.50000000  0.50000000  0.00000000  1.0
  Ir  Ir12  1  0.50000000  0.00000000  0.50000000  1.0
  Ir  Ir13  1  0.00000000  0.50000000  0.50000000  1.0
  Ir  Ir14  1  0.59896439  0.09832881  0.59896439  1.0
  Ir  Ir15  1  0.59896439  0.59896439  0.09832881  1.0
  Ir  Ir16  1  0.09832881  0.59896439  0.59896439  1.0
  Ir  Ir17  1  0.40103561  0.40103561  0.90167119  1.0

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