CaAl9Co2

High-Entropy Materials HEA Traditional Materials TRA Elasticity Data ELA

MP-ID: mp-11350 · Space group: P6/mmm (#191)

Materials Project API

Basic Information

Formula

CaAl9Co2

MP-ID

mp-11350

Elements

Sites

Density

3.2676

g/cm³

Volume

203.67

Å³

Cell a

7.8208

Cell b

7.8208

Cell c

3.8449

α Angle

90.00

β Angle

90.00

γ Angle

120.00

Space Group

P6/mmm

Point Group

6/mmm

Crystal System

Hexagonal

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
13.07	6.7730	100.0	(1,0,-1,0)
22.74	3.9104	82.0	(2,-1,-1,0)
23.13	3.8449	12.0	(0,0,0,1)
26.66	3.3437	3.6	(1,0,-1,1)
32.66	2.7416	97.9	(2,-1,-1,1)
35.05	2.5600	6.3	(3,-1,-2,0)
35.05	2.5600	1.3	(1,-3,2,0)
35.32	2.5413	51.6	(2,0,-2,1)
39.93	2.2577	1.4	(3,0,-3,0)
39.93	2.2577	2.8	(3,-3,0,0)
42.42	2.1309	26.0	(3,-1,-2,1)
42.42	2.1309	52.0	(3,-2,-1,1)
46.44	1.9552	38.5	(4,-2,-2,0)
46.44	1.9552	19.2	(2,-4,2,0)
46.65	1.9469	22.9	(3,0,-3,1)
46.65	1.9469	45.7	(3,-3,0,1)
47.28	1.9225	38.8	(0,0,0,2)
48.46	1.8785	6.6	(4,-1,-3,0)
48.46	1.8785	6.6	(3,-4,1,0)
49.27	1.8494	6.3	(1,0,-1,2)
52.51	1.7428	30.2	(4,-2,-2,1)
52.51	1.7428	15.1	(2,-4,2,1)
53.08	1.7252	9.6	(2,-1,-1,2)
53.08	1.7252	4.8	(1,-2,1,2)

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Energy Properties

Formation Energy/atom

-0.38118

eV/atom

Energy/atom

-8.22249

eV/atom

Energy above Hull

0.0000

eV/atom

Uncorrected Energy

-8.2225

eV/atom

Volume/atom

16.97

Å³

c/a Ratio

0.4916

Electronic Properties

Metallic

Metal

Band Gap

Direct Gap

CBM

N/A

Magnetic Properties

Magnetic

Yes

Total Mag. Moment

0.0000

μB

Mag. Ordering

Unknown

Mag. Sites

Magnetization/Volume

0.000000

μB/Å³

Elastic Properties

K_VRH

87.080

GPa

G_VRH

56.558

GPa

Young's Modulus E

139.477

GPa

Poisson Ratio ν

0.233

Pugh Ratio K/G

1.540

Vickers Hardness Est.

9.792

GPa

Ductility

Ductile

Anisotropy

0.094

Lame λ

49.375

GPa

Feature Analysis

Composition Overview

Element Composition (atomic fraction)

Composition Info

Major / Matrix Element

Al · 0.750

Element Family

PostTransition-Noble

Solute Fraction

0.250

Interstitial Fraction

0.000

High-Entropy Alloy Features

Composite Radar (normalized)

Element-Class Share

Mix Entropy ΔS/R

0.7215

HEA criterion (>1.0 = high entropy)

Mix Entropy ΔS

5.9982

J/mol·K

Ω Parameter

0.4316

Ω > 1.1 favors solid solution

Atomic Size Mismatch δr

11.881%

δr < 6.6% favors single-phase solid solution

Electronegativity Diff Δχ

0.2077

smaller = more stable mixing

VEC

3.917

valence electron concentration, affects phase stability

Mix Enthalpy ΔH_mix

-15.116

kJ/mol; negative = exothermic mixing

Entropy Norm

0.6567

SS Former

Phase Tendency

Traditional Material Features

ROM Blended-Feature Radar

Rating & Classification

Tier

Score

0.833

Family

Al-based Alloy

Matrix Element

Al · 0.750

Elasticity Features

Elastic Modulus Comparison (GPa)

Elastic Features

Elastic Anisotropy A^U

0.0940

Homogeneous Poisson ν

0.2330

Debye Temperature

533.9

Sound Velocity

4,609.8

m/s

Homogeneity

0.2330

Related Tasks

Related computation task IDs (5)

aaadnakz aaadsmlb aaaemuur aaaeuacs aaafwymo

Citation & References

Materials Project Page

https://materialsproject.org/materials/mp-11350

Reference Citation

The crystal structure and related material properties of CaAl9Co2 were obtained from the Materials Project database (MP-ID: mp-11350, 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_CaAl9Co2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.82078903
_cell_length_b   7.82078740
_cell_length_c   3.84492519
_cell_angle_alpha   90.00000000
_cell_angle_beta   90.00000000
_cell_angle_gamma   119.99999442
_symmetry_Int_Tables_number   1
_chemical_formula_structural   CaAl9Co2
_chemical_formula_sum   'Ca1 Al9 Co2'
_cell_volume   203.66650048
_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  -0.00000000  -0.00000000  0.00000000  1.0
  Al  Al1  1  0.50000000  -0.00000000  0.00000000  1.0
  Al  Al2  1  0.50000000  0.50000000  0.00000000  1.0
  Al  Al3  1  -0.00000000  0.50000000  0.00000000  1.0
  Al  Al4  1  0.21341441  0.42682582  0.50000000  1.0
  Al  Al5  1  0.78658559  0.21341441  0.50000000  1.0
  Al  Al6  1  0.42682582  0.21341441  0.50000000  1.0
  Al  Al7  1  0.57317418  0.78658559  0.50000000  1.0
  Al  Al8  1  0.21341441  0.78658559  0.50000000  1.0
  Al  Al9  1  0.78658559  0.57317418  0.50000000  1.0
  Co  Co10  1  0.33333300  0.66666700  0.00000000  1.0
  Co  Co11  1  0.66666700  0.33333300  0.00000000  1.0

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