RbCa(FeAs)4

High-Entropy Materials HEA

MP-ID: mp-1078332 · Space group: P4/mmm (#123)

Materials Project API

Basic Information

Formula

RbCa(FeAs)4

MP-ID

mp-1078332

Elements

Sites

Density

5.6635

g/cm³

Volume

190.17

Å³

Cell a

3.9391

Cell b

3.9391

Cell c

12.2564

α Angle

90.00

β Angle

90.00

γ Angle

90.00

Space Group

P4/mmm

Point Group

4/mmm

Crystal System

Tetragonal

Bravais Lattice

Stability

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
7.21	12.2564	11.6	(0,0,1)
14.45	6.1282	39.4	(0,0,2)
21.75	4.0855	7.0	(0,0,3)
22.57	3.9391	1.5	(1,0,0)
23.73	3.7502	3.2	(1,0,1)
26.91	3.3136	20.6	(1,0,2)
29.14	3.0641	2.7	(0,0,4)
31.55	2.8357	100.0	(1,0,3)
32.14	2.7854	12.8	(1,1,0)
32.98	2.7161	1.2	(1,1,1)
35.40	2.5357	31.7	(1,1,2)
37.18	2.4185	2.4	(1,0,4)
39.14	2.3014	5.8	(1,1,3)
43.48	2.0812	3.9	(1,0,5)
43.93	2.0611	14.3	(1,1,4)
44.35	2.0427	1.6	(0,0,6)
46.09	1.9695	51.4	(2,0,0)
48.55	1.8751	6.5	(2,0,2)
49.54	1.8402	40.3	(1,1,5)
50.32	1.8134	1.8	(1,0,6)
51.51	1.7741	2.5	(2,0,3)
52.25	1.7509	1.1	(0,0,7)
54.17	1.6931	5.9	(2,1,2)
55.46	1.6568	1.4	(2,0,4)

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Energy Properties

Formation Energy/atom

-0.38734

eV/atom

Energy/atom

-5.94201

eV/atom

Energy above Hull

0.0102

eV/atom

Uncorrected Energy

-5.9420

eV/atom

Volume/atom

19.02

Å³

c/a Ratio

3.1115

Electronic Properties

Metallic

Metal

Band Gap

Direct Gap

CBM

N/A

Magnetic Properties

Magnetic

Yes

Total Mag. Moment

0.9004

μB

Mag. Ordering

Mag. Sites

Magnetization/Volume

0.004730

μB/Å³

Elastic Properties

Elastic data not available

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

1.1936

HEA criterion (>1.0 = high entropy)

Mix Entropy ΔS

9.9232

J/mol·K

Ω Parameter

4.0410

Ω > 1.1 favors solid solution

Atomic Size Mismatch δr

28.253%

δr < 6.6% favors single-phase solid solution

Electronegativity Diff Δχ

0.4669

smaller = more stable mixing

VEC

4.700

valence electron concentration, affects phase stability

Mix Enthalpy ΔH_mix

3.200

kJ/mol; negative = exothermic mixing

Entropy Norm

0.8610

SS Former

Phase Tendency

Related Tasks

Related computation task IDs (1)

aaaejaaf

Citation & References

Materials Project Page

https://materialsproject.org/materials/mp-1078332

Reference Citation

The crystal structure and related material properties of RbCa(FeAs)4 were obtained from the Materials Project database (MP-ID: mp-1078332, 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_RbCa(FeAs)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.93908100
_cell_length_b   3.93908100
_cell_length_c   12.25637600
_cell_angle_alpha   90.00000000
_cell_angle_beta   90.00000000
_cell_angle_gamma   90.00000000
_symmetry_Int_Tables_number   1
_chemical_formula_structural   RbCa(FeAs)4
_chemical_formula_sum   'Rb1 Ca1 Fe4 As4'
_cell_volume   190.17433158
_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  0.50000000  0.50000000  0.50000000  1.0
  Ca  Ca1  1  0.00000000  0.00000000  0.00000000  1.0
  Fe  Fe2  1  0.50000000  0.00000000  0.77998800  1.0
  Fe  Fe3  1  0.00000000  0.50000000  0.77998800  1.0
  Fe  Fe4  1  0.50000000  0.00000000  0.22001200  1.0
  Fe  Fe5  1  0.00000000  0.50000000  0.22001200  1.0
  As  As6  1  0.00000000  0.00000000  0.67853700  1.0
  As  As7  1  0.00000000  0.00000000  0.32146300  1.0
  As  As8  1  0.50000000  0.50000000  0.87629400  1.0
  As  As9  1  0.50000000  0.50000000  0.12370600  1.0

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