K3Ta8O21

High-Entropy Materials HEA Traditional Materials TRA

MP-ID: mp-757546 · Space group: P6_3/mcm (#193)

Materials Project API

Basic Information

Formula

K3Ta8O21

MP-ID

mp-757546

Elements

Sites

Density

7.1569

g/cm³

Volume

882.08

Å³

Cell a

9.1729

Cell b

9.1729

Cell c

12.1050

α Angle

90.00

β Angle

90.00

γ Angle

120.00

Space Group

P6_3/mcm

Point Group

6/mmm

Crystal System

Hexagonal

Bravais Lattice

Hexagonal P

Stability

Yes

Packing Fraction

0.7400

X-ray Diffraction

Diffraction Pattern

Target / Radiation

X-axis: 2θ (°); Y-axis: relative intensity; CuKa ; λ=1.5406 Å

Diffraction Peaks (Top 24)

2θ	d (Å)	I	hkl
11.14	7.9439	31.9	(1,0,-1,0)
14.64	6.0525	91.4	(0,0,0,2)
20.71	4.2889	60.3	(2,-1,-1,1)
22.38	3.9720	17.5	(2,-2,0,0)
22.38	3.9720	35.1	(2,0,-2,0)
24.35	3.6555	23.6	(2,-1,-1,2)
24.35	3.6555	4.7	(1,1,-2,-2)
26.85	3.3208	19.9	(2,-2,0,2)
26.85	3.3208	19.9	(2,0,-2,2)
29.48	3.0295	100.0	(2,-1,-1,3)
29.48	3.0295	20.0	(1,1,-2,-3)
29.52	3.0263	6.1	(0,0,0,4)
29.76	3.0025	42.3	(3,-1,-2,0)
29.76	3.0025	21.1	(2,1,-3,0)
30.68	2.9142	11.5	(3,-2,-1,-1)
30.68	2.9142	46.2	(3,-1,-2,1)
30.68	2.9142	11.5	(2,1,-3,-1)
31.64	2.8280	29.6	(1,0,-1,4)
33.31	2.6897	16.2	(3,-1,-2,2)
33.31	2.6897	8.1	(2,1,-3,2)
33.85	2.6480	9.8	(3,-3,0,0)
33.85	2.6480	19.5	(3,0,-3,0)
35.54	2.5259	12.1	(2,-1,-1,-4)
35.54	2.5259	24.2	(2,-1,-1,4)

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Energy Properties

Formation Energy/atom

-3.22014

eV/atom

Energy/atom

-9.54003

eV/atom

Energy above Hull

0.0000

eV/atom

Uncorrected Energy

-19.6429

eV/atom

Volume/atom

13.78

Å³

c/a Ratio

1.3197

Electronic Properties

Metallic

Metal

Band Gap

Direct Gap

CBM

N/A

Magnetic Properties

Magnetic

Total Mag. Moment

0.0000

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 · 0.656

Element Family

Metalloid-Nonmetal

Solute Fraction

0.344

Interstitial Fraction

0.000

High-Entropy Alloy Features

Composite Radar (normalized)

Element-Class Share

Mix Entropy ΔS/R

0.8449

HEA criterion (>1.0 = high entropy)

Mix Entropy ΔS

7.0246

J/mol·K

Ω Parameter

0.0000

Ω > 1.1 favors solid solution

Atomic Size Mismatch δr

55.966%

δr < 6.6% favors single-phase solid solution

Electronegativity Diff Δχ

1.0250

smaller = more stable mixing

VEC

3.969

valence electron concentration, affects phase stability

Mix Enthalpy ΔH_mix

0.000

kJ/mol; negative = exothermic mixing

Entropy Norm

0.7691

SS Former

Phase Tendency

Traditional Material Features

ROM Blended-Feature Radar

Rating & Classification

Tier

Score

0.608

Family

O-rich Multi-Component

Matrix Element

O · 0.656

Related Tasks

Related computation task IDs (2)

aaabyqpd aaagadgg

Citation & References

Materials Project Page

https://materialsproject.org/materials/mp-757546

Reference Citation

The crystal structure and related material properties of K3Ta8O21 were obtained from the Materials Project database (MP-ID: mp-757546, 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

BibTeX

@article{Horton2025,
  author  = {Horton, Matthew K. and Huck, Patrick and Yang, Ruo Xi and Munro, Jason M. and Dwaraknath, Shyam and Ganose, Alex M. and Kingsbury, Ryan S. and Wen, Mingjian and Shen, Jimmy X. and Mathis, Tyler S. and Kaplan, Aaron D. and Berket, Karlo and Riebesell, Janosh and George, Janine and Rosen, Andrew S. and Spotte-Smith, Evan W. C. and McDermott, Matthew J. and Cohen, Orion A. and Dunn, Alex and Kuner, Matthew C. and Rignanese, Gian-Marco and Petretto, Guido and Waroquiers, David and Griffin, Sinead M. and Neaton, Jeffrey B. and Chrzan, Daryl C. and Asta, Mark and Hautier, Geoffroy and Cholia, Shreyas and Ceder, Gerbrand and Ong, Shyue Ping and Jain, Anubhav and Persson, Kristin A.},
  title   = {Accelerated data-driven materials science with the Materials Project},
  journal = {Nature Materials},
  year    = {2025},
  volume  = {24},
  number  = {10},
  pages   = {1522--1532},
  month   = {oct},
  doi     = {10.1038/s41563-025-02272-0},
  issn    = {1476-4660},
  url     = {https://doi.org/10.1038/s41563-025-02272-0},
  abstract = {The Materials Project was launched formally in 2011 to drive materials discovery forwards through high-throughput computation and open data. More than a decade later, the Materials Project has become an indispensable tool used by more than 600,000 materials researchers around the world. This Perspective describes how the Materials Project, as a data platform and a software ecosystem, has helped to shape research in data-driven materials science. We cover how sustainable software and computational methods have accelerated materials design while becoming more open source and collaborative in nature. Next, we present cases where the Materials Project was used to understand and discover functional materials. We then describe our efforts to meet the needs of an expanding user base, through technical infrastructure updates ranging from data architecture and cloud resources to interactive web applications. Finally, we discuss opportunities to better aid the research community, with the vision that more accessible and easy-to-understand materials data will result in democratized materials knowledge and an increasingly collaborative community.}
}

3D Crystal Structure Rendering

Loading 3D structure…

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Raw CIF Data

# generated using pymatgen
data_K3Ta8O21
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.17286550
_cell_length_b   9.17286545
_cell_length_c   12.10500708
_cell_angle_alpha   89.99999109
_cell_angle_beta   90.00000486
_cell_angle_gamma   120.00001866
_symmetry_Int_Tables_number   1
_chemical_formula_structural   K3Ta8O21
_chemical_formula_sum   'K6 Ta16 O42'
_cell_volume   882.07527098
_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
  K  K0  1  -0.00000015  0.59223230  0.25000233  1.0
  K  K1  1  0.00000001  0.40776703  0.74999766  1.0
  K  K2  1  0.40776736  0.40776768  0.25000231  1.0
  K  K3  1  0.59223287  0.59223276  0.74999764  1.0
  K  K4  1  0.40776780  0.00000023  0.74999764  1.0
  K  K5  1  0.59223247  -0.00000014  0.25000214  1.0
  Ta  Ta6  1  -0.00000008  0.75214930  0.59475935  1.0
  Ta  Ta7  1  -0.00000003  0.75216113  0.90518991  1.0
  Ta  Ta8  1  0.00000006  0.24785025  0.40524079  1.0
  Ta  Ta9  1  0.00000001  0.24783850  0.09480977  1.0
  Ta  Ta10  1  0.33333303  0.66666681  0.49999981  1.0
  Ta  Ta11  1  0.33333313  0.66666677  0.00000022  1.0
  Ta  Ta12  1  0.24783924  0.24783926  0.90518995  1.0
  Ta  Ta13  1  0.24785119  0.24785116  0.59475949  1.0
  Ta  Ta14  1  0.24783849  0.00000009  0.09480981  1.0
  Ta  Ta15  1  0.24785035  0.00000010  0.40524068  1.0
  Ta  Ta16  1  0.75216128  0.75216130  0.09480974  1.0
  Ta  Ta17  1  0.75214930  0.75214939  0.40524062  1.0
  Ta  Ta18  1  0.66666693  0.33333331  0.49999972  1.0
  Ta  Ta19  1  0.66666680  0.33333336  0.00000024  1.0
  Ta  Ta20  1  0.75214916  -0.00000013  0.59475941  1.0
  Ta  Ta21  1  0.75216100  -0.00000002  0.90518999  1.0
  O  O22  1  -0.00000021  0.80162871  0.07419021  1.0
  O  O23  1  -0.00000007  0.80163435  0.42582869  1.0
  O  O24  1  -0.00000017  0.79239813  0.74998165  1.0
  O  O25  1  0.16781622  0.68654818  0.90505151  1.0
  O  O26  1  0.16782211  0.68655471  0.59492309  1.0
  O  O27  1  0.00000021  0.20760181  0.25001824  1.0
  O  O28  1  0.31345202  0.83218402  0.09494831  1.0
  O  O29  1  0.31344547  0.83217808  0.40507701  1.0
  O  O30  1  0.00000010  0.19836582  0.57417130  1.0
  O  O31  1  0.00000010  0.19837133  0.92580980  1.0
  O  O32  1  0.16781591  0.48126820  0.09494828  1.0
  O  O33  1  0.16782177  0.48126767  0.40507709  1.0
  O  O34  1  0.31345211  0.48126842  0.90505149  1.0
  O  O35  1  0.31344558  0.48126779  0.59492309  1.0
  O  O36  1  0.19837142  0.19837136  0.07419031  1.0
  O  O37  1  0.19836612  0.19836601  0.42582871  1.0
  O  O38  1  0.51873227  0.83217787  0.59492304  1.0
  O  O39  1  0.51873175  0.83218386  0.90505165  1.0
  O  O40  1  0.20760186  0.20760186  0.74998174  1.0
  O  O41  1  0.51873230  0.68655426  0.40507709  1.0
  O  O42  1  0.51873161  0.68654754  0.09494833  1.0
  O  O43  1  0.19837137  0.00000016  0.92580977  1.0
  O  O44  1  0.19836603  0.00000016  0.57417124  1.0
  O  O45  1  0.20760181  0.00000022  0.25001822  1.0
  O  O46  1  0.48126836  0.31345222  0.90505161  1.0
  O  O47  1  0.48126782  0.31344559  0.59492306  1.0
  O  O48  1  0.79239812  0.79239812  0.25001818  1.0
  O  O49  1  0.48126816  0.16781588  0.09494830  1.0
  O  O50  1  0.48126766  0.16782195  0.40507709  1.0
  O  O51  1  0.80163377  0.80163392  0.57417127  1.0
  O  O52  1  0.80162851  0.80162850  0.92580970  1.0
  O  O53  1  0.68654760  0.51873165  0.09494838  1.0
  O  O54  1  0.68655416  0.51873227  0.40507699  1.0
  O  O55  1  0.83217793  0.51873241  0.59492305  1.0
  O  O56  1  0.83218381  0.51873179  0.90505156  1.0
  O  O57  1  0.68655477  0.16782224  0.59492302  1.0
  O  O58  1  0.68654821  0.16781632  0.90505155  1.0
  O  O59  1  0.83217821  0.31344565  0.40507707  1.0
  O  O60  1  0.83218400  0.31345207  0.09494831  1.0
  O  O61  1  0.79239809  -0.00000022  0.74998174  1.0
  O  O62  1  0.80163424  -0.00000010  0.42582871  1.0
  O  O63  1  0.80162867  -0.00000022  0.07419029  1.0

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