Ba(NiO2)4

High-Entropy Materials HEA Traditional Materials TRA

MP-ID: mp-1047829 · Space group: P-31m (#162)

Materials Project API

Basic Information

Formula

Ba(NiO2)4

MP-ID

mp-1047829

Elements

Sites

Density

4.1191

g/cm³

Volume

201.60

Å³

Cell a

5.4845

Cell b

5.4845

Cell c

7.7391

α Angle

90.00

β Angle

90.00

γ Angle

120.00

Space Group

P-31m

Point Group

-3m

Crystal System

Trigonal

Bravais Lattice

Stability

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
11.43	7.7391	66.7	(0,0,0,1)
18.68	4.7498	1.5	(1,0,-1,0)
21.96	4.0481	36.3	(1,0,-1,1)
22.98	3.8695	17.4	(0,0,0,2)
29.78	3.0000	100.0	(1,0,-1,2)
32.65	2.7423	88.6	(2,-1,-1,0)
34.71	2.5848	50.0	(2,-1,-1,1)
34.78	2.5797	4.8	(0,0,0,3)
39.70	2.2704	6.9	(2,0,-2,1)
39.76	2.2669	15.1	(1,0,-1,3)
40.31	2.2374	2.1	(2,-1,-1,2)
40.31	2.2374	1.0	(1,1,-2,2)
44.78	2.0241	26.3	(2,0,-2,2)
46.96	1.9348	14.6	(0,0,0,4)
48.45	1.8790	1.7	(2,-1,-1,3)
52.31	1.7488	7.3	(3,-1,-2,1)
52.36	1.7472	8.7	(2,0,-2,3)
56.51	1.6285	19.8	(3,-1,-2,2)
56.51	1.6285	9.9	(2,1,-3,2)
58.28	1.5833	9.1	(3,-3,0,0)
58.28	1.5833	18.2	(3,0,-3,0)
58.37	1.5809	33.3	(2,-1,-1,4)
59.60	1.5511	1.9	(3,-3,0,1)
59.60	1.5511	3.8	(3,0,-3,1)

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Energy Properties

Formation Energy/atom

-0.82650

eV/atom

Energy/atom

-5.79752

eV/atom

Energy above Hull

0.4371

eV/atom

Uncorrected Energy

-4.5929

eV/atom

Volume/atom

15.51

Å³

c/a Ratio

1.4111

Electronic Properties

Metallic

Metal

Band Gap

Direct Gap

CBM

N/A

Magnetic Properties

Magnetic

Yes

Total Mag. Moment

9.9987

μB

Mag. Ordering

Mag. Sites

Magnetization/Volume

0.049600

μB/Å³

Elastic Properties

Elastic data not available

Feature Analysis

Composition Overview

Element Composition (atomic fraction)

Composition Info

Major / Matrix Element

O · 0.615

Element Family

Metalloid-Nonmetal

Solute Fraction

0.385

Interstitial Fraction

0.000

High-Entropy Alloy Features

Composite Radar (normalized)

Element-Class Share

Mix Entropy ΔS/R

0.8587

HEA criterion (>1.0 = high entropy)

Mix Entropy ΔS

7.1396

J/mol·K

Ω Parameter

0.0000

Ω > 1.1 favors solid solution

Atomic Size Mismatch δr

50.125%

δr < 6.6% favors single-phase solid solution

Electronegativity Diff Δχ

0.8807

smaller = more stable mixing

VEC

5.692

valence electron concentration, affects phase stability

Mix Enthalpy ΔH_mix

0.000

kJ/mol; negative = exothermic mixing

Entropy Norm

0.7817

SS Former

Phase Tendency

Traditional Material Features

ROM Blended-Feature Radar

Rating & Classification

Tier

Score

0.394

Family

O-rich Multi-Component

Matrix Element

O · 0.615

Related Tasks

Related computation task IDs (3)

aaachqbl aaaduywa aaaeagvb

Citation & References

Materials Project Page

https://materialsproject.org/materials/mp-1047829

Reference Citation

The crystal structure and related material properties of Ba(NiO2)4 were obtained from the Materials Project database (MP-ID: mp-1047829, 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

Loading 3D structure…

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Raw CIF Data

# generated using pymatgen
data_Ba(NiO2)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.48453866
_cell_length_b   5.48453866
_cell_length_c   7.73908300
_cell_angle_alpha   90.00000000
_cell_angle_beta   90.00000000
_cell_angle_gamma   120.00000798
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ba(NiO2)4
_chemical_formula_sum   'Ba1 Ni4 O8'
_cell_volume   201.60453897
_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
  Ba  Ba0  1  0.00000000  0.00000000  0.00000000  1.0
  Ni  Ni1  1  0.33333300  0.66666700  0.76474800  1.0
  Ni  Ni2  1  0.66666700  0.33333300  0.76474800  1.0
  Ni  Ni3  1  0.33333300  0.66666700  0.23525200  1.0
  Ni  Ni4  1  0.66666700  0.33333300  0.23525200  1.0
  O  O5  1  0.35977400  0.35977400  0.70717000  1.0
  O  O6  1  0.64022600  0.00000000  0.70717000  1.0
  O  O7  1  0.00000000  0.64022600  0.70717000  1.0
  O  O8  1  0.64022600  0.64022600  0.29283000  1.0
  O  O9  1  0.00000000  0.35977400  0.29283000  1.0
  O  O10  1  0.35977400  0.00000000  0.29283000  1.0
  O  O11  1  0.33333300  0.66666700  0.00000000  1.0
  O  O12  1  0.66666700  0.33333300  0.00000000  1.0

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