CaPa5(Al3Os)8

High-Entropy Materials HEA

MP-ID: mp-3292465 · Space group: Amm2 (#38)

Materials Project API

Basic Information

Formula

CaPa5(Al3Os)8

MP-ID

mp-3292465

Elements

Sites

Density

8.8135

g/cm³

Volume

633.93

Å³

Cell a

8.8263

Cell b

8.8263

Cell c

9.3805

α Angle

90.00

β Angle

90.00

γ Angle

119.83

Space Group

Amm2

Point Group

mm2

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
9.43	9.3805	5.0	(0,0,0,1)
11.56	7.6567	4.0	(0,1,-1,0)
11.56	7.6567	4.0	(1,0,-1,0)
11.59	7.6373	1.3	(1,-1,0,0)
14.94	5.9316	7.8	(0,1,-1,1)
14.94	5.9316	7.8	(1,0,-1,1)
14.96	5.9226	32.8	(1,-1,0,1)
18.92	4.6902	4.3	(0,0,0,2)
20.07	4.4243	4.0	(1,1,-2,0)
22.23	3.9995	2.7	(1,0,-1,2)
22.26	3.9933	1.9	(2,-1,-1,1)
23.23	3.8283	15.1	(0,2,-2,0)
23.23	3.8283	15.1	(2,0,-2,0)
23.29	3.8187	10.4	(2,-2,0,0)
25.12	3.5445	31.8	(2,0,-2,1)
25.18	3.5368	13.6	(2,-2,0,1)
27.72	3.2184	4.8	(1,1,-2,2)
27.76	3.2140	1.1	(2,-1,-1,2)
30.13	2.9658	100.0	(2,0,-2,2)
30.18	2.9613	60.3	(2,-2,0,2)
30.88	2.8961	7.2	(2,1,-3,0)
30.89	2.8947	4.9	(1,0,-1,3)
30.90	2.8937	7.6	(1,-1,0,3)
30.93	2.8908	4.0	(1,-3,2,0)

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Energy Properties

Formation Energy/atom

-0.60897

eV/atom

Energy/atom

-26.31346

eV/atom

Energy above Hull

0.0000

eV/atom

Uncorrected Energy

-26.3135

eV/atom

Volume/atom

16.68

Å³

c/a Ratio

1.0628

Electronic Properties

Metallic

Metal

Band Gap

Direct Gap

CBM

N/A

Magnetic Properties

Magnetic

Total Mag. Moment

0.0197

μB

Mag. Ordering

Mag. Sites

Magnetization/Volume

0.000030

μB/Å³

Elastic Properties

Elastic data not available

Feature Analysis

Composition Overview

Element Composition (atomic fraction)

Composition Info

Major / Matrix Element

Al · 0.632

Element Family

PostTransition-Noble

Solute Fraction

0.368

Interstitial Fraction

0.000

High-Entropy Alloy Features

Composite Radar (normalized)

Element-Class Share

Mix Entropy ΔS/R

0.9808

HEA criterion (>1.0 = high entropy)

Mix Entropy ΔS

8.1548

J/mol·K

Ω Parameter

2.5590

Ω > 1.1 favors solid solution

Atomic Size Mismatch δr

10.693%

δr < 6.6% favors single-phase solid solution

Electronegativity Diff Δχ

0.2755

smaller = more stable mixing

VEC

4.182

valence electron concentration, affects phase stability

Mix Enthalpy ΔH_mix

-4.962

kJ/mol; negative = exothermic mixing

Entropy Norm

0.7075

SS Former

Phase Tendency

Related Tasks

Related computation task IDs (1)

aaahfinh

Citation & References

Materials Project Page

https://materialsproject.org/materials/mp-3292465

Reference Citation

The crystal structure and related material properties of CaPa5(Al3Os)8 were obtained from the Materials Project database (MP-ID: mp-3292465, 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_CaPa5(Al3Os)8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.82626129
_cell_length_b   8.82626346
_cell_length_c   9.38044673
_cell_angle_alpha   90.00000000
_cell_angle_beta   90.00000000
_cell_angle_gamma   119.83222237
_symmetry_Int_Tables_number   1
_chemical_formula_structural   CaPa5(Al3Os)8
_chemical_formula_sum   'Ca1 Pa5 Al24 Os8'
_cell_volume   633.92747506
_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  0.80381509  0.19618491  0.75000000  1.0
  Pa  Pa1  1  0.19479801  0.39552551  0.25000000  1.0
  Pa  Pa2  1  0.79839363  0.60697465  0.75000000  1.0
  Pa  Pa3  1  0.60447449  0.80520199  0.25000000  1.0
  Pa  Pa4  1  0.39302535  0.20160637  0.75000000  1.0
  Pa  Pa5  1  0.19957960  0.80042040  0.25000000  1.0
  Al  Al6  1  0.33508357  0.66491643  0.01043324  1.0
  Al  Al7  1  0.67032688  0.32967312  0.98180205  1.0
  Al  Al8  1  0.67032688  0.32967312  0.51819795  1.0
  Al  Al9  1  0.33508357  0.66491643  0.48956676  1.0
  Al  Al10  1  0.16064739  0.32390472  0.57847299  1.0
  Al  Al11  1  0.83701629  0.67509884  0.42035323  1.0
  Al  Al12  1  0.67609528  0.83935261  0.57847299  1.0
  Al  Al13  1  0.83701629  0.67509884  0.07964677  1.0
  Al  Al14  1  0.32490116  0.16298371  0.42035323  1.0
  Al  Al15  1  0.16064739  0.32390472  0.92152701  1.0
  Al  Al16  1  0.16237578  0.83762422  0.58122246  1.0
  Al  Al17  1  0.32490116  0.16298371  0.07964677  1.0
  Al  Al18  1  0.83783317  0.16216683  0.42270502  1.0
  Al  Al19  1  0.67609528  0.83935261  0.92152701  1.0
  Al  Al20  1  0.83783317  0.16216683  0.07729498  1.0
  Al  Al21  1  0.16237578  0.83762422  0.91877754  1.0
  Al  Al22  1  0.56488460  0.12968889  0.25000000  1.0
  Al  Al23  1  0.44169389  0.88167152  0.75000000  1.0
  Al  Al24  1  0.87031111  0.43511540  0.25000000  1.0
  Al  Al25  1  0.11832848  0.55830611  0.75000000  1.0
  Al  Al26  1  0.56174186  0.43825814  0.25000000  1.0
  Al  Al27  1  0.43413814  0.56586186  0.75000000  1.0
  Al  Al28  1  0.00038409  0.99961591  0.25000000  1.0
  Al  Al29  1  0.00067354  0.99932646  0.75000000  1.0
  Os  Os30  1  0.49517870  0.99446025  0.00686169  1.0
  Os  Os31  1  0.00553975  0.50482130  0.00686169  1.0
  Os  Os32  1  0.49517870  0.99446025  0.49313831  1.0
  Os  Os33  1  0.50152606  0.49847394  0.99761685  1.0
  Os  Os34  1  0.00553975  0.50482130  0.49313831  1.0
  Os  Os35  1  0.50152606  0.49847394  0.50238315  1.0
  Os  Os36  1  0.00035754  0.99964246  0.00024220  1.0
  Os  Os37  1  0.00035754  0.99964246  0.49975780  1.0

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