Ca(NiO2)2
High-Entropy Materials HEA Traditional Materials TRAMP-ID: mp-1040970 · Space group: P1 (#1)
Basic Information
Formula
Ca(NiO2)2
MP-ID
mp-1040970
Elements
3
Sites
42
Density
4.5128
g/cm³
Volume
488.94
ų
Cell a
6.0931
Å
Cell b
6.1965
Å
Cell c
14.8544
Å
α Angle
91.91
°
β Angle
89.75
°
γ Angle
119.27
°
Space Group
P1
Point Group
1
Crystal System
Triclinic
Bravais Lattice
aP
Stability
No
Packing Fraction
-
X-ray Diffraction
Diffraction Pattern
X-axis: 2θ (°); Y-axis: relative intensity; Cu Kα ; λ=1.5418 Å
Diffraction Peaks (Top 24)
| 2θ | d (Å) | I | hkl |
|---|---|---|---|
| 5.95 | 14.8447 | 6.5 | (0,0,1) |
| 11.92 | 7.4223 | 3.1 | (0,0,2) |
| 16.41 | 5.4021 | 3.4 | (0,1,0) |
| 16.68 | 5.3149 | 4.3 | (1,0,0) |
| 16.73 | 5.2996 | 4.6 | (1,-1,0) |
| 17.27 | 5.1359 | 4.5 | (0,1,-1) |
| 17.65 | 5.0259 | 49.5 | (1,0,-1) |
| 17.65 | 5.0253 | 49.8 | (1,-1,1) |
| 17.67 | 5.0190 | 49.5 | (0,1,1) |
| 17.80 | 4.9821 | 3.4 | (1,0,1) |
| 17.89 | 4.9576 | 3.1 | (1,-1,-1) |
| 17.93 | 4.9482 | 100.0 | (0,0,3) |
| 19.98 | 4.4442 | 1.7 | (0,1,-2) |
| 20.38 | 4.3574 | 4.5 | (1,-1,2) |
| 20.42 | 4.3498 | 4.4 | (1,0,-2) |
| 20.68 | 4.2951 | 4.9 | (0,1,2) |
| 23.98 | 3.7112 | 1.0 | (0,0,4) |
| 24.35 | 3.6561 | 1.3 | (1,-1,3) |
| 24.41 | 3.6468 | 1.2 | (1,0,-3) |
| 28.75 | 3.1049 | 23.2 | (1,1,0) |
| 28.84 | 3.0958 | 22.9 | (1,-2,0) |
| 29.08 | 3.0710 | 27.8 | (1,-1,4) |
| 29.16 | 3.0627 | 27.3 | (1,0,-4) |
| 29.32 | 3.0465 | 22.4 | (2,-1,0) |
Energy Properties
Formation Energy/atom
-1.58418
eV/atom
Energy/atom
-6.34957
eV/atom
Energy above Hull
0.0779
eV/atom
Uncorrected Energy
-5.2310
eV/atom
Volume/atom
11.64
ų
c/a Ratio
2.4379
Electronic Properties
Metallic
Metal
Band Gap
0
eV
Direct Gap
No
CBM
N/A
eV
Magnetic Properties
Magnetic
Yes
Total Mag. Moment
14.0001
μB
Mag. Ordering
FiM
Mag. Sites
13
Magnetization/Volume
0.028630
μB/ų
Elastic Properties
Elastic data not available
Feature Analysis
Composition Overview
Element Composition (atomic fraction)
Composition Info
Major / Matrix Element
O · 0.571
Element Family
Metalloid-Nonmetal
Solute Fraction
0.429
Interstitial Fraction
0.000
High-Entropy Alloy Features
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
0
Phase Tendency
IM
Traditional Material Features
ROM Blended-Feature Radar
Rating & Classification
Tier
B
Score
0.510
Family
O-rich Multi-Component
Matrix Element
O · 0.571
Related Tasks
Related computation task IDs (1)
Citation & References
Materials Project Page
https://materialsproject.org/materials/mp-1040970
Reference Citation
The crystal structure and related material properties of Ca(NiO2)2 were obtained from the Materials Project database (MP-ID: mp-1040970, 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_Ca(NiO2)2
_symmetry_space_group_name_H-M 'P 1'
_cell_length_a 6.09314500
_cell_length_b 6.19648250
_cell_length_c 14.85435992
_cell_angle_alpha 91.91185045
_cell_angle_beta 89.75402756
_cell_angle_gamma 119.26570736
_symmetry_Int_Tables_number 1
_chemical_formula_structural Ca(NiO2)2
_chemical_formula_sum 'Ca6 Ni12 O24'
_cell_volume 488.93864021
_cell_formula_units_Z 6
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 0.83247500 0.66653900 0.95792600 1.0
Ca Ca1 1 0.50244900 0.00011600 0.61339600 1.0
Ca Ca2 1 0.50122300 0.00304700 0.00362300 1.0
Ca Ca3 1 0.16493000 0.33076900 0.27354400 1.0
Ca Ca4 1 0.83140900 0.66345500 0.71688900 1.0
Ca Ca5 1 0.50050300 0.00282600 0.36888400 1.0
Ni Ni6 1 0.33078700 0.16166600 0.83006700 1.0
Ni Ni7 1 0.33378500 0.66927400 0.82757300 1.0
Ni Ni8 1 0.00356000 0.50121500 0.49734500 1.0
Ni Ni9 1 0.83085300 0.16244200 0.82944400 1.0
Ni Ni10 1 0.16621000 0.32745900 0.66390000 1.0
Ni Ni11 1 0.00288900 0.00403200 0.49763200 1.0
Ni Ni12 1 0.66963200 0.82536900 0.17135200 1.0
Ni Ni13 1 0.49878800 0.50009200 0.49710900 1.0
Ni Ni14 1 0.15509800 0.82441300 0.17169600 1.0
Ni Ni15 1 0.83578100 0.67601400 0.33934300 1.0
Ni Ni16 1 0.67220400 0.34564400 0.17224700 1.0
Ni Ni17 1 0.16673900 0.33358300 0.04724700 1.0
O O18 1 0.64603200 0.29504200 0.89245200 1.0
O O19 1 0.49481600 0.99383000 0.75591100 1.0
O O20 1 0.19871100 0.85012400 0.89173700 1.0
O O21 1 0.65095400 0.84941100 0.88975100 1.0
O O22 1 0.02539000 0.46161300 0.76044500 1.0
O O23 1 0.31384300 0.61016400 0.57328100 1.0
O O24 1 0.43260600 0.45924700 0.75818100 1.0
O O25 1 0.16828000 0.33413800 0.92211700 1.0
O O26 1 0.89475300 0.18766300 0.57416300 1.0
O O27 1 0.17685000 0.36221300 0.42851500 1.0
O O28 1 0.02802000 0.05391700 0.76226400 1.0
O O29 1 0.29475300 0.17895000 0.57019100 1.0
O O30 1 0.70791100 0.82680500 0.42419700 1.0
O O31 1 0.96710100 0.93381700 0.26064500 1.0
O O32 1 0.11390100 0.81919200 0.42259800 1.0
O O33 1 0.82382500 0.63623400 0.56639200 1.0
O O34 1 0.82937200 0.65638100 0.10795400 1.0
O O35 1 0.56419000 0.54153300 0.26103400 1.0
O O36 1 0.69356500 0.39948300 0.41778100 1.0
O O37 1 0.96985800 0.53630500 0.26126500 1.0
O O38 1 0.32409400 0.17412500 0.10056000 1.0
O O39 1 0.50324200 0.00864600 0.22244600 1.0
O O40 1 0.84835100 0.17224200 0.09966300 1.0
O O41 1 0.33026600 0.66097500 0.09724100 1.0
