Sm2CoNiH8

High-Entropy Materials HEA

MP-ID: mp-3251891 · Space group: Amm2 (#38)

Materials Project API

Basic Information

Formula

Sm2CoNiH8

MP-ID

mp-3251891

Elements

Sites

Density

6.8068

g/cm³

Volume

104.02

Å³

Cell a

6.1385

Cell b

6.1385

Cell c

4.8379

α Angle

90.00

β Angle

90.00

γ Angle

145.21

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
23.85	3.7302	36.0	(1,-1,1)
25.43	3.5028	8.3	(1,0,0)
30.52	2.9288	47.0	(2,-2,0)
31.53	2.8372	100.0	(1,0,1)
33.50	2.6746	11.2	(1,-2,0)
33.50	2.6746	11.2	(2,-1,0)
35.84	2.5055	9.4	(2,-2,1)
37.17	2.4189	33.3	(0,0,2)
38.46	2.3407	61.3	(2,-1,1)
45.57	1.9905	2.2	(0,1,2)
45.57	1.9905	2.2	(1,0,2)
48.83	1.8651	25.9	(2,-2,2)
49.67	1.8354	15.3	(1,1,0)
49.87	1.8285	9.1	(2,-3,1)
49.87	1.8285	9.1	(3,-2,1)
50.40	1.8107	8.7	(3,-3,1)
50.90	1.7941	14.4	(2,-1,2)
55.83	1.6468	7.8	(2,0,1)
59.43	1.5552	13.9	(3,-1,0)
59.45	1.5548	3.3	(1,-1,3)
60.83	1.5228	10.0	(4,-3,0)
62.76	1.4806	3.4	(3,-1,1)
63.51	1.4648	13.1	(1,0,3)
63.53	1.4644	3.0	(4,-4,0)

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Energy Properties

Formation Energy/atom

-0.52958

eV/atom

Energy/atom

-9.88981

eV/atom

Energy above Hull

0.0000

eV/atom

Uncorrected Energy

-9.8898

eV/atom

Volume/atom

8.67

Å³

c/a Ratio

0.7881

Electronic Properties

Metallic

Metal

Band Gap

Direct Gap

CBM

N/A

Magnetic Properties

Magnetic

Yes

Total Mag. Moment

0.9999

μB

Mag. Ordering

FiM

Mag. Sites

Magnetization/Volume

0.009610

μB/Å³

Elastic Properties

Elastic data not available

Feature Analysis

Composition Overview

Element Composition (atomic fraction)

Composition Info

Major / Matrix Element

H · 0.667

Element Family

Alkali-AlkEarth

Solute Fraction

0.333

Interstitial Fraction

0.000

High-Entropy Alloy Features

Composite Radar (normalized)

Element-Class Share

Mix Entropy ΔS/R

0.9831

HEA criterion (>1.0 = high entropy)

Mix Entropy ΔS

8.1734

J/mol·K

Ω Parameter

0.0000

Ω > 1.1 favors solid solution

Atomic Size Mismatch δr

93.201%

δr < 6.6% favors single-phase solid solution

Electronegativity Diff Δχ

0.3780

smaller = more stable mixing

VEC

3.250

valence electron concentration, affects phase stability

Mix Enthalpy ΔH_mix

0.000

kJ/mol; negative = exothermic mixing

Entropy Norm

0.7091

SS Former

Phase Tendency

Related Tasks

Related computation task IDs (1)

aaahdamt

Citation & References

Materials Project Page

https://materialsproject.org/materials/mp-3251891

Reference Citation

The crystal structure and related material properties of Sm2CoNiH8 were obtained from the Materials Project database (MP-ID: mp-3251891, 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_Sm2CoNiH8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.13847083
_cell_length_b   6.13847104
_cell_length_c   4.83788288
_cell_angle_alpha   90.00000000
_cell_angle_beta   90.00000000
_cell_angle_gamma   145.20568392
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Sm2CoNiH8
_chemical_formula_sum   'Sm2 Co1 Ni1 H8'
_cell_volume   104.02361925
_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
  Sm  Sm0  1  0.86662883  0.13337117  0.75000000  1.0
  Sm  Sm1  1  0.13253750  0.86746250  0.25000000  1.0
  Co  Co2  1  0.40515917  0.59484083  0.25000000  1.0
  Ni  Ni3  1  0.59416239  0.40583761  0.75000000  1.0
  H  H4  1  0.08738557  0.91261443  0.75000000  1.0
  H  H5  1  0.91323711  0.08676289  0.25000000  1.0
  H  H6  1  0.69086145  0.30913855  0.50701629  1.0
  H  H7  1  0.30843005  0.69156995  0.49265728  1.0
  H  H8  1  0.69086145  0.30913855  0.99298371  1.0
  H  H9  1  0.30843005  0.69156995  0.00734272  1.0
  H  H10  1  0.50115321  0.49884679  0.99839704  1.0
  H  H11  1  0.50115321  0.49884679  0.50160296  1.0

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