Rb(FeAs)2

High-Entropy Materials HEA Traditional Materials TRA Elasticity Data ELA

MP-ID: mp-975359 · Space group: I4/mmm (#139)

Materials Project API

Basic Information

Formula

Rb(FeAs)2

MP-ID

mp-975359

Elements

Sites

Density

5.6455

g/cm³

Volume

102.07

Å³

Cell a

8.1291

Cell b

8.1291

Cell c

8.1291

α Angle

154.14

β Angle

154.14

γ Angle

36.90

Space Group

I4/mmm

Point Group

4/mmm

Crystal System

Tetragonal

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
11.48	7.7113	31.3	(1,1,-1)
23.07	3.8557	6.1	(2,2,-2)
30.09	2.9697	100.0	(2,1,-1)
34.88	2.5725	9.2	(0,0,1)
34.91	2.5704	2.7	(3,3,-3)
36.83	2.4403	25.5	(1,1,0)
38.25	2.3527	6.7	(3,2,-2)
42.23	2.1399	17.2	(2,2,-1)
47.14	1.9278	7.8	(4,4,-4)
48.29	1.8846	1.7	(4,3,-3)
50.15	1.8191	27.2	(1,-1,1)
50.17	1.8183	46.1	(3,3,-2)
51.63	1.7705	2.4	(2,0,0)
55.89	1.6452	1.8	(3,1,-1)
59.60	1.5512	27.7	(2,1,0)
59.64	1.5503	8.2	(5,4,-4)
59.98	1.5423	2.0	(5,5,-5)
62.56	1.4849	2.2	(4,2,-2)
64.78	1.4391	2.8	(3,2,-1)
71.28	1.3231	8.6	(5,3,-3)
72.17	1.3088	1.0	(4,3,-2)
72.21	1.3083	4.3	(6,5,-5)
73.65	1.2863	8.3	(0,0,2)
73.72	1.2852	2.1	(6,6,-6)

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Energy Properties

Formation Energy/atom

-0.26476

eV/atom

Energy/atom

-5.71692

eV/atom

Energy above Hull

0.0000

eV/atom

Uncorrected Energy

-14.6620

eV/atom

Volume/atom

20.41

Å³

c/a Ratio

1.0000

Electronic Properties

Metallic

Metal

Band Gap

Direct Gap

CBM

N/A

Magnetic Properties

Magnetic

Yes

Total Mag. Moment

3.0980

μB

Mag. Ordering

Unknown

Mag. Sites

Magnetization/Volume

0.030350

μB/Å³

Elastic Properties

K_VRH

39.583

GPa

G_VRH

24.942

GPa

Young's Modulus E

61.838

GPa

Poisson Ratio ν

0.240

Pugh Ratio K/G

1.587

Vickers Hardness Est.

4.648

GPa

Ductility

Ductile

Anisotropy

0.596

Lame λ

22.955

GPa

Feature Analysis

Composition Overview

Element Composition (atomic fraction)

Composition Info

Major / Matrix Element

Fe · 0.400

Element Family

3d-TM

Solute Fraction

0.600

Interstitial Fraction

0.000

High-Entropy Alloy Features

Composite Radar (normalized)

Element-Class Share

Mix Entropy ΔS/R

1.0549

HEA criterion (>1.0 = high entropy)

Mix Entropy ΔS

8.7706

J/mol·K

Ω Parameter

0.0000

Ω > 1.1 favors solid solution

Atomic Size Mismatch δr

32.122%

δr < 6.6% favors single-phase solid solution

Electronegativity Diff Δχ

0.4992

smaller = more stable mixing

VEC

4.600

valence electron concentration, affects phase stability

Mix Enthalpy ΔH_mix

0.000

kJ/mol; negative = exothermic mixing

Entropy Norm

0.9602

SS Former

Phase Tendency

Traditional Material Features

ROM Blended-Feature Radar

Rating & Classification

Tier

Score

0.553

Family

Fe-rich Multi-Component

Matrix Element

Fe · 0.400

Elasticity Features

Elastic Modulus Comparison (GPa)

Elastic Features

Elastic Anisotropy A^U

0.5960

Homogeneous Poisson ν

0.2400

Debye Temperature

370.4

Sound Velocity

2,330.7

m/s

Homogeneity

0.2400

Related Tasks

Related computation task IDs (5)

aaadmeyv aaadwedb aaaelxip aaaeslse aaafsgxk

Citation & References

Materials Project Page

https://materialsproject.org/materials/mp-975359

Reference Citation

The crystal structure and related material properties of Rb(FeAs)2 were obtained from the Materials Project database (MP-ID: mp-975359, 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_Rb(FeAs)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.12910941
_cell_length_b   8.12910941
_cell_length_c   8.12910941
_cell_angle_alpha   154.13879400
_cell_angle_beta   154.13879400
_cell_angle_gamma   36.89790161
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Rb(FeAs)2
_chemical_formula_sum   'Rb1 Fe2 As2'
_cell_volume   102.06604932
_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
  Rb  Rb0  1  -0.00000000  -0.00000000  0.00000000  1.0
  Fe  Fe1  1  0.75000000  0.25000000  0.50000000  1.0
  Fe  Fe2  1  0.25000000  0.75000000  0.50000000  1.0
  As  As3  1  0.34952521  0.34952521  0.00000000  1.0
  As  As4  1  0.65047479  0.65047479  -0.00000000  1.0

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