Sr2AlTlFe2O7

High-Entropy Materials HEA

MP-ID: mp-1045986 · Space group: P4/mmm (#123)

Materials Project API

Basic Information

Formula

Sr2AlTlFe2O7

MP-ID

mp-1045986

Elements

Sites

Density

5.6910

g/cm³

Volume

183.91

Å³

Cell a

3.7370

Cell b

3.7370

Cell c

13.1689

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
6.71	13.1689	55.0	(0,0,1)
13.45	6.5845	7.9	(0,0,2)
20.23	4.3896	5.0	(0,0,3)
23.81	3.7370	8.4	(1,0,0)
24.77	3.5951	4.3	(1,0,1)
27.08	3.2922	1.8	(0,0,4)
27.44	3.2501	34.2	(1,0,2)
31.44	2.8455	100.0	(1,0,3)
33.92	2.6425	50.2	(1,1,0)
34.04	2.6338	23.1	(0,0,5)
34.62	2.5908	22.3	(1,1,1)
36.37	2.4703	1.6	(1,0,4)
39.82	2.2639	2.3	(1,1,3)
41.13	2.1948	7.6	(0,0,6)
41.97	2.1528	3.0	(1,0,5)
43.94	2.0608	7.1	(1,1,4)
48.08	1.8926	1.0	(1,0,6)
48.73	1.8685	27.3	(2,0,0)
48.82	1.8654	18.0	(1,1,5)
49.25	1.8500	2.7	(2,0,1)
50.79	1.7975	1.2	(2,0,2)
53.28	1.7192	1.5	(2,0,3)
54.34	1.6884	22.9	(1,1,6)
54.62	1.6804	1.9	(1,0,7)

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Energy Properties

Formation Energy/atom

-2.07659

eV/atom

Energy/atom

-6.77488

eV/atom

Energy above Hull

0.3480

eV/atom

Uncorrected Energy

-6.0579

eV/atom

Volume/atom

14.15

Å³

c/a Ratio

3.5239

Electronic Properties

Metallic

Metal

Band Gap

Direct Gap

CBM

N/A

Magnetic Properties

Magnetic

Yes

Total Mag. Moment

9.8566

μB

Mag. Ordering

Mag. Sites

Magnetization/Volume

0.053590

μB/Å³

Elastic Properties

Elastic data not available

Feature Analysis

Composition Overview

Element Composition (atomic fraction)

Composition Info

Major / Matrix Element

O · 0.538

Element Family

Metalloid-Nonmetal

Solute Fraction

0.462

Interstitial Fraction

0.000

High-Entropy Alloy Features

Composite Radar (normalized)

Element-Class Share

Mix Entropy ΔS/R

1.3039

HEA criterion (>1.0 = high entropy)

Mix Entropy ΔS

10.8404

J/mol·K

Ω Parameter

11.3140

Ω > 1.1 favors solid solution

Atomic Size Mismatch δr

51.243%

δr < 6.6% favors single-phase solid solution

Electronegativity Diff Δχ

1.0169

smaller = more stable mixing

VEC

4.154

valence electron concentration, affects phase stability

Mix Enthalpy ΔH_mix

0.561

kJ/mol; negative = exothermic mixing

Entropy Norm

0.8101

SS Former

Phase Tendency

Related Tasks

Related computation task IDs (3)

aaachnjc aaaduqbv aaadxqbc

Citation & References

Materials Project Page

https://materialsproject.org/materials/mp-1045986

Reference Citation

The crystal structure and related material properties of Sr2AlTlFe2O7 were obtained from the Materials Project database (MP-ID: mp-1045986, 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_Sr2AlTlFe2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.73703700
_cell_length_b   3.73703700
_cell_length_c   13.16892000
_cell_angle_alpha   90.00000000
_cell_angle_beta   90.00000000
_cell_angle_gamma   90.00000000
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Sr2AlTlFe2O7
_chemical_formula_sum   'Sr2 Al1 Tl1 Fe2 O7'
_cell_volume   183.90983507
_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
  Sr  Sr0  1  0.50000000  0.50000000  0.81323800  1.0
  Sr  Sr1  1  0.50000000  0.50000000  0.18676200  1.0
  Al  Al2  1  0.50000000  0.50000000  0.50000000  1.0
  Tl  Tl3  1  0.00000000  0.00000000  0.00000000  1.0
  Fe  Fe4  1  0.00000000  0.00000000  0.63913700  1.0
  Fe  Fe5  1  0.00000000  0.00000000  0.36086300  1.0
  O  O6  1  0.50000000  0.00000000  0.59280000  1.0
  O  O7  1  0.00000000  0.50000000  0.59280000  1.0
  O  O8  1  0.50000000  0.00000000  0.40720000  1.0
  O  O9  1  0.00000000  0.50000000  0.40720000  1.0
  O  O10  1  0.00000000  0.00000000  0.78550600  1.0
  O  O11  1  0.00000000  0.00000000  0.21449400  1.0
  O  O12  1  0.50000000  0.50000000  0.00000000  1.0

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