K2BaNb3O9

High-Entropy Materials HEA

MP-ID: mp-3292070 · Space group: P-3m1 (#164)

Materials Project API

Basic Information

Formula

K2BaNb3O9

MP-ID

mp-3292070

Elements

Sites

Density

5.2554

g/cm³

Volume

201.66

Å³

Cell a

5.7483

Cell b

5.7483

Cell c

7.0471

α Angle

90.00

β Angle

90.00

γ Angle

120.00

Space Group

P-3m1

Point Group

-3m

Crystal System

Trigonal

Bravais Lattice

Stability

Yes

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
12.56	7.0471	20.5	(0,0,0,1)
17.82	4.9782	10.7	(1,-1,0,0)
17.82	4.9782	10.7	(0,1,-1,0)
17.82	4.9782	10.7	(1,0,-1,0)
21.86	4.0660	7.3	(1,-1,0,1)
21.86	4.0660	27.6	(1,-1,0,-1)
21.86	4.0660	21.1	(1,0,-1,1)
21.86	4.0660	7.3	(0,1,-1,1)
25.28	3.5236	3.8	(0,0,0,2)
31.10	2.8760	68.8	(1,-1,0,2)
31.10	2.8760	3.1	(0,1,-1,-2)
31.10	2.8760	3.1	(1,-1,0,-2)
31.10	2.8760	71.9	(1,0,-1,2)
31.10	2.8760	68.8	(0,1,-1,2)
31.12	2.8742	68.8	(1,-2,1,0)
31.12	2.8742	68.8	(2,-1,-1,0)
31.12	2.8742	68.8	(1,1,-2,0)
33.68	2.6613	2.0	(1,-2,1,1)
33.68	2.6613	2.0	(2,-1,-1,1)
33.68	2.6613	4.0	(2,-1,-1,-1)
33.68	2.6613	2.0	(1,1,-2,-1)
33.68	2.6613	2.0	(1,1,-2,1)
36.08	2.4891	1.9	(2,-2,0,0)
36.08	2.4891	1.9	(0,2,-2,0)

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Energy Properties

Formation Energy/atom

-2.81495

eV/atom

Energy/atom

-13.91436

eV/atom

Energy above Hull

0.0000

eV/atom

Uncorrected Energy

-13.9144

eV/atom

Volume/atom

13.44

Å³

c/a Ratio

1.2259

Electronic Properties

Metallic

Metal

Band Gap

Direct Gap

CBM

N/A

Magnetic Properties

Magnetic

Total Mag. Moment

0.0006

μB

Mag. Ordering

Mag. Sites

Magnetization/Volume

0.000000

μB/Å³

Elastic Properties

Elastic data not available

Feature Analysis

Composition Overview

Element Composition (atomic fraction)

Composition Info

Major / Matrix Element

O · 0.600

Element Family

Metalloid-Nonmetal

Solute Fraction

0.400

Interstitial Fraction

0.000

High-Entropy Alloy Features

Composite Radar (normalized)

Element-Class Share

Mix Entropy ΔS/R

1.0776

HEA criterion (>1.0 = high entropy)

Mix Entropy ΔS

8.9589

J/mol·K

Ω Parameter

0.0000

Ω > 1.1 favors solid solution

Atomic Size Mismatch δr

58.861%

δr < 6.6% favors single-phase solid solution

Electronegativity Diff Δχ

1.1129

smaller = more stable mixing

VEC

3.667

valence electron concentration, affects phase stability

Mix Enthalpy ΔH_mix

0.000

kJ/mol; negative = exothermic mixing

Entropy Norm

0.7773

SS Former

Phase Tendency

Related Tasks

Related computation task IDs (1)

aaahfhyc

Citation & References

Materials Project Page

https://materialsproject.org/materials/mp-3292070

Reference Citation

The crystal structure and related material properties of K2BaNb3O9 were obtained from the Materials Project database (MP-ID: mp-3292070, 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_K2BaNb3O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.74832814
_cell_length_b   5.74833092
_cell_length_c   7.04711063
_cell_angle_alpha   90.00014208
_cell_angle_beta   89.99991634
_cell_angle_gamma   120.00022234
_symmetry_Int_Tables_number   1
_chemical_formula_structural   K2BaNb3O9
_chemical_formula_sum   'K2 Ba1 Nb3 O9'
_cell_volume   201.66199585
_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
  K  K0  1  0.66666708  0.33333227  0.33603486  1.0
  K  K1  1  0.33333292  0.66666773  0.66396514  1.0
  Ba  Ba2  1  0.00000000  0.00000000  0.00000000  1.0
  Nb  Nb3  1  0.00000000  0.00000000  0.50000000  1.0
  Nb  Nb4  1  0.66666947  0.33333486  0.82924241  1.0
  Nb  Nb5  1  0.33333053  0.66666514  0.17075759  1.0
  O  O6  1  0.66905227  0.83452719  0.33112932  1.0
  O  O7  1  0.33094773  0.16547281  0.66887068  1.0
  O  O8  1  0.00000000  0.50000000  0.00000000  1.0
  O  O9  1  0.83452677  0.66905056  0.66887038  1.0
  O  O10  1  0.50000000  0.00000000  0.00000000  1.0
  O  O11  1  0.16547323  0.33094944  0.33112962  1.0
  O  O12  1  0.83452586  0.16547490  0.66887010  1.0
  O  O13  1  0.50000000  0.50000000  0.00000000  1.0
  O  O14  1  0.16547414  0.83452510  0.33112990  1.0

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