NaNiO2

High-Entropy Materials HEA Traditional Materials TRA

MP-ID: mp-971634 · Space group: P6_3/mmc (#194)

Materials Project API

Basic Information

Formula

NaNiO2

MP-ID

mp-971634

Elements

Sites

Density

4.5396

g/cm³

Volume

83.17

Å³

Cell a

2.9988

Cell b

2.9988

Cell c

10.6790

α Angle

90.00

β Angle

90.00

γ Angle

120.00

Space Group

P6_3/mmc

Point Group

6/mmm

Crystal System

Hexagonal

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 19)

2θ	d (Å)	I	hkl
16.60	5.3395	78.1	(0,0,0,2)
33.57	2.6698	19.5	(0,0,0,4)
34.54	2.5970	17.4	(1,0,-1,0)
38.55	2.3354	100.0	(1,0,-1,2)
43.12	2.0980	31.1	(1,0,-1,3)
48.93	1.8616	39.2	(1,0,-1,4)
55.72	1.6496	2.1	(1,0,-1,5)
61.88	1.4994	29.7	(2,-1,-1,0)
63.35	1.4681	32.1	(1,0,-1,6)
64.56	1.4436	6.5	(2,-1,-1,2)
64.56	1.4436	3.3	(1,1,-2,2)
70.55	1.3349	4.1	(0,0,0,8)
72.27	1.3073	12.6	(2,-1,-1,4)
72.84	1.2985	2.2	(2,0,-2,0)
75.32	1.2617	12.3	(2,0,-2,2)
78.39	1.2199	3.4	(2,0,-2,3)
80.98	1.1872	5.1	(1,0,-1,8)
82.63	1.1677	2.4	(2,-2,0,4)
82.63	1.1677	4.8	(2,0,-2,4)

Get direct link

Energy Properties

Formation Energy/atom

-1.30498

eV/atom

Energy/atom

-5.55942

eV/atom

Energy above Hull

0.0282

eV/atom

Uncorrected Energy

-4.5807

eV/atom

Volume/atom

10.40

Å³

c/a Ratio

3.5611

Electronic Properties

Metallic

Metal

Band Gap

Direct Gap

CBM

N/A

Magnetic Properties

Magnetic

Yes

Total Mag. Moment

2.0050

μB

Mag. Ordering

Mag. Sites

Magnetization/Volume

0.024110

μB/Å³

Elastic Properties

Elastic data not available

Feature Analysis

Composition Overview

Element Composition (atomic fraction)

Composition Info

Major / Matrix Element

O · 0.500

Element Family

Metalloid-Nonmetal

Solute Fraction

0.500

Interstitial Fraction

0.000

High-Entropy Alloy Features

Composite Radar (normalized)

Element-Class Share

Mix Entropy ΔS/R

1.0397

HEA criterion (>1.0 = high entropy)

Mix Entropy ΔS

8.6442

J/mol·K

Ω Parameter

0.7906

Ω > 1.1 favors solid solution

Atomic Size Mismatch δr

48.664%

δr < 6.6% favors single-phase solid solution

Electronegativity Diff Δχ

1.0678

smaller = more stable mixing

VEC

4.750

valence electron concentration, affects phase stability

Mix Enthalpy ΔH_mix

-6.037

kJ/mol; negative = exothermic mixing

Entropy Norm

0.9464

SS Former

Phase Tendency

Traditional Material Features

ROM Blended-Feature Radar

Rating & Classification

Tier

Score

0.450

Family

O-rich Multi-Component

Matrix Element

O · 0.500

Related Tasks

Related computation task IDs (5)

aaadbttd aaadongx aaadvutf aaaepnem aaafbibb

Citation & References

Materials Project Page

https://materialsproject.org/materials/mp-971634

Reference Citation

The crystal structure and related material properties of NaNiO2 were obtained from the Materials Project database (MP-ID: mp-971634, 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…

Style: Ball & Stick | Drag to rotate · Scroll to zoom · Right-click to pan

Raw CIF Data

# generated using pymatgen
data_NaNiO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.99877806
_cell_length_b   2.99877806
_cell_length_c   10.67902100
_cell_angle_alpha   90.00000000
_cell_angle_beta   90.00000000
_cell_angle_gamma   120.00000137
_symmetry_Int_Tables_number   1
_chemical_formula_structural   NaNiO2
_chemical_formula_sum   'Na2 Ni2 O4'
_cell_volume   83.16693881
_cell_formula_units_Z   2
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
  Na  Na0  1  0.66666700  0.33333300  0.25000000  1.0
  Na  Na1  1  0.33333300  0.66666700  0.75000000  1.0
  Ni  Ni2  1  0.00000000  0.00000000  0.50000000  1.0
  Ni  Ni3  1  0.00000000  0.00000000  0.00000000  1.0
  O  O4  1  0.33333300  0.66666700  0.40289600  1.0
  O  O5  1  0.66666700  0.33333300  0.59710400  1.0
  O  O6  1  0.66666700  0.33333300  0.90289600  1.0
  O  O7  1  0.33333300  0.66666700  0.09710400  1.0

Get direct link