Ca2Nb2BiO8

High-Entropy Materials HEA

MP-ID: mp-1042164 · Space group: C2/c (#15)

Materials Project API

Basic Information

Formula

Ca2Nb2BiO8

MP-ID

mp-1042164

Elements

Sites

Density

5.3854

g/cm³

Volume

371.82

Å³

Cell a

10.5965

Cell b

10.5965

Cell c

5.5839

α Angle

88.90

β Angle

88.90

γ Angle

36.38

Space Group

C2/c

Point Group

2/m

Crystal System

Monoclinic

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
8.79	10.0648	100.0	(1,1,0)
17.62	5.0324	4.3	(2,2,0)
18.84	4.7110	56.0	(2,1,0)
21.22	4.1871	8.8	(1,0,1)
21.35	4.1610	8.1	(1,0,-1)
24.55	3.6258	92.4	(2,1,1)
24.90	3.5756	75.3	(2,1,-1)
25.91	3.4392	57.9	(3,2,0)
26.57	3.3549	10.5	(3,3,0)
26.95	3.3080	23.2	(1,-1,0)
28.40	3.1426	9.1	(2,0,0)
30.29	2.9509	96.2	(3,2,1)
30.77	2.9059	94.2	(3,2,-1)
31.43	2.8459	92.5	(1,-1,1)
32.06	2.7914	61.1	(0,0,2)
32.39	2.7643	6.2	(3,1,0)
32.61	2.7459	6.7	(2,0,1)
32.79	2.7312	6.6	(2,0,-1)
33.13	2.7039	3.3	(1,1,2)
33.49	2.6760	8.4	(1,1,-2)
35.09	2.5571	1.6	(1,0,2)
35.68	2.5162	15.8	(4,4,0)
36.10	2.4882	8.7	(3,1,1)
36.43	2.4664	1.8	(3,1,-1)

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Energy Properties

Formation Energy/atom

-2.83402

eV/atom

Energy/atom

-8.04076

eV/atom

Energy above Hull

0.1667

eV/atom

Uncorrected Energy

-7.6180

eV/atom

Volume/atom

14.30

Å³

c/a Ratio

0.5270

Electronic Properties

Metallic

Metal

Band Gap

Direct Gap

CBM

N/A

Magnetic Properties

Magnetic

Yes

Total Mag. Moment

2.0005

μB

Mag. Ordering

Mag. Sites

Magnetization/Volume

0.005380

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

1.0720

HEA criterion (>1.0 = high entropy)

Mix Entropy ΔS

8.9127

J/mol·K

Ω Parameter

3.4511

Ω > 1.1 favors solid solution

Atomic Size Mismatch δr

53.972%

δr < 6.6% favors single-phase solid solution

Electronegativity Diff Δχ

1.0013

smaller = more stable mixing

VEC

3.923

valence electron concentration, affects phase stability

Mix Enthalpy ΔH_mix

1.731

kJ/mol; negative = exothermic mixing

Entropy Norm

0.7733

SS Former

Phase Tendency

Related Tasks

Related computation task IDs (2)

aaachhvw aaaeatzw

Citation & References

Materials Project Page

https://materialsproject.org/materials/mp-1042164

Reference Citation

The crystal structure and related material properties of Ca2Nb2BiO8 were obtained from the Materials Project database (MP-ID: mp-1042164, 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_Ca2Nb2BiO8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.59644551
_cell_length_b   10.59644551
_cell_length_c   5.58391897
_cell_angle_alpha   88.90348164
_cell_angle_beta   88.90348164
_cell_angle_gamma   36.38105876
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ca2Nb2BiO8
_chemical_formula_sum   'Ca4 Nb4 Bi2 O16'
_cell_volume   371.82446292
_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  0.87323300  0.55803500  0.75442800  1.0
  Ca  Ca1  1  0.44196500  0.12676700  0.74557200  1.0
  Ca  Ca2  1  0.12676700  0.44196500  0.24557200  1.0
  Ca  Ca3  1  0.55803500  0.87323300  0.25442800  1.0
  Nb  Nb4  1  0.02780100  0.73168600  0.74223500  1.0
  Nb  Nb5  1  0.26831400  0.97219900  0.75776500  1.0
  Nb  Nb6  1  0.97219900  0.26831400  0.25776500  1.0
  Nb  Nb7  1  0.73168600  0.02780100  0.24223500  1.0
  Bi  Bi8  1  0.67737300  0.32262700  0.75000000  1.0
  Bi  Bi9  1  0.32262700  0.67737300  0.25000000  1.0
  O  O10  1  0.02937600  0.82538800  0.06152400  1.0
  O  O11  1  0.17461200  0.97062400  0.43847600  1.0
  O  O12  1  0.97062400  0.17461200  0.93847600  1.0
  O  O13  1  0.82538800  0.02937600  0.56152400  1.0
  O  O14  1  0.28980400  0.58229300  0.60705500  1.0
  O  O15  1  0.41770700  0.71019600  0.89294500  1.0
  O  O16  1  0.71019600  0.41770700  0.39294500  1.0
  O  O17  1  0.58229300  0.28980400  0.10705500  1.0
  O  O18  1  0.89260000  0.73793700  0.47189700  1.0
  O  O19  1  0.26206300  0.10740000  0.02810300  1.0
  O  O20  1  0.47448300  0.14756800  0.35219800  1.0
  O  O21  1  0.85243200  0.52551700  0.14780200  1.0
  O  O22  1  0.52551700  0.85243200  0.64780200  1.0
  O  O23  1  0.14756800  0.47448300  0.85219800  1.0
  O  O24  1  0.73793700  0.89260000  0.97189700  1.0
  O  O25  1  0.10740000  0.26206300  0.52810300  1.0

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