Ca(NiO2)2

高熵材料 HEA 传统材料 TRA

MP-ID: mp-1042020 · Space group: Imma (#74)

Materials Project API

Basic Information

Formula

Ca(NiO2)2

MP-ID

mp-1042020

Elements

Sites

Density

4.4868

g/cm³

Volume

163.92

Å³

Cell a

6.1083

Cell b

6.1083

Cell c

6.1083

α Angle

118.90

β Angle

118.73

γ Angle

92.06

Space Group

Imma

Point Group

mmm

Crystal System

Orthorhombic

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
17.67	5.0184	3.4	(0,1,-1)
17.70	5.0103	19.9	(1,0,-1)
28.68	3.1124	6.0	(1,-1,1)
28.75	3.1047	25.0	(1,-1,-1)
29.26	3.0522	49.2	(1,1,-2)
33.91	2.6438	100.0	(1,-2,1)
33.95	2.6403	68.1	(2,-1,-1)
34.85	2.5742	26.5	(1,2,-2)
34.87	2.5731	46.6	(2,1,-2)
35.79	2.5092	10.8	(0,2,-2)
35.85	2.5052	3.6	(2,0,-2)
41.06	2.1981	26.3	(2,-2,0)
42.64	2.1205	10.9	(2,2,-2)
45.79	1.9817	1.5	(3,0,-2)
46.54	1.9515	4.3	(3,-1,-1)
47.61	1.9099	1.6	(2,2,-3)
51.17	1.7851	10.4	(1,-3,2)
51.26	1.7822	10.1	(3,-1,-2)
52.20	1.7524	7.9	(1,3,-3)
52.24	1.7510	1.7	(3,1,-3)
54.26	1.6905	13.7	(2,-3,1)
54.32	1.6890	26.9	(3,-2,-1)
54.89	1.6728	7.4	(0,3,-3)
54.98	1.6701	10.8	(3,0,-3)

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Energy Properties

Formation Energy/atom

-1.42470

eV/atom

Energy/atom

-6.19009

eV/atom

Energy above Hull

0.2374

eV/atom

Uncorrected Energy

-5.0715

eV/atom

Volume/atom

11.71

Å³

c/a Ratio

1.0000

Electronic Properties

Metallic

Metal

Band Gap

Direct Gap

CBM

N/A

Magnetic Properties

Magnetic

Yes

Total Mag. Moment

8.0000

μB

Mag. Ordering

Mag. Sites

Magnetization/Volume

0.048800

μB/Å³

Elastic Properties

Elastic data not available

Feature Analysis

Element Composition (atomic fraction)

Composition Info

Major / Matrix Element

O · 0.571

Element Family

Metalloid-Nonmetal

Solute Fraction

0.429

Interstitial Fraction

0.000

Composite Radar (normalized)

Element-Class Share

Mix Entropy ΔS/R

0.9557

HEA criterion (>1.0 = high entropy)

Mix Entropy ΔS

7.9457

J/mol·K

Ω Parameter

1.6573

Ω > 1.1 favors solid solution

Atomic Size Mismatch δr

50.254%

δr < 6.6% favors single-phase solid solution

Electronegativity Diff Δχ

0.9497

smaller = more stable mixing

VEC

5.429

valence electron concentration, affects phase stability

Mix Enthalpy ΔH_mix

-3.281

kJ/mol; negative = exothermic mixing

Entropy Norm

0.8699

SS Former

Phase Tendency

Related Tasks

Related computation task IDs (3)

aaachhnb aaadupue aaaefvrs

Citation & References

Materials Project Page

https://materialsproject.org/materials/mp-1042020

Reference Citation

The crystal structure and related material properties of Ca(NiO2)2 were obtained from the Materials Project database (MP-ID: mp-1042020, 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_Ca(NiO2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.10834330
_cell_length_b   6.10834330
_cell_length_c   6.10834330
_cell_angle_alpha   118.90148836
_cell_angle_beta   118.73475066
_cell_angle_gamma   92.05962322
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ca(NiO2)2
_chemical_formula_sum   'Ca2 Ni4 O8'
_cell_volume   163.92324021
_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
  Ca  Ca0  1  0.50000000  0.00000000  0.00000000  1.0
  Ca  Ca1  1  0.50000000  0.50000000  0.50000000  1.0
  Ni  Ni2  1  0.88926100  0.13926100  0.75000000  1.0
  Ni  Ni3  1  0.11073900  0.86073900  0.25000000  1.0
  Ni  Ni4  1  0.50000000  0.50000000  0.00000000  1.0
  Ni  Ni5  1  0.00000000  0.50000000  0.50000000  1.0
  O  O6  1  0.73801400  0.72778100  0.01023300  1.0
  O  O7  1  0.23262300  0.72371200  0.99108900  1.0
  O  O8  1  0.21754800  0.72778100  0.48976700  1.0
  O  O9  1  0.23262300  0.24153400  0.50891100  1.0
  O  O10  1  0.76737700  0.75846600  0.49108900  1.0
  O  O11  1  0.76737700  0.27628800  0.00891100  1.0
  O  O12  1  0.78245200  0.27221900  0.51023300  1.0
  O  O13  1  0.26198600  0.27221900  0.98976700  1.0

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