CsK5Ru2O9

High-Entropy Materials HEA

MP-ID: mp-654335 · Space group: Pnma (#62)

Materials Project API

Basic Information

Formula

CsK5Ru2O9

MP-ID

mp-654335

Elements

Sites

Density

3.3939

g/cm³

Volume

1,320.13

Å³

Cell a

8.3633

Cell b

9.1702

Cell c

17.2133

α Angle

90.00

β Angle

90.00

γ Angle

90.00

Space Group

Pnma

Point Group

mmm

Crystal System

Orthorhombic

Bravais Lattice

Stability

Yes

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
14.33	6.1793	16.5	(1,1,0)
14.77	5.9979	2.0	(1,0,2)
15.23	5.8159	3.4	(1,1,1)
17.67	5.0196	19.2	(1,1,2)
19.36	4.5851	28.2	(0,2,0)
20.04	4.4306	3.2	(0,2,1)
20.64	4.3033	28.5	(0,0,4)
21.13	4.2047	4.0	(1,1,3)
21.25	4.1816	27.3	(2,0,0)
21.96	4.0467	7.9	(0,2,2)
23.25	3.8265	3.5	(1,0,4)
23.66	3.7612	7.1	(2,0,2)
24.44	3.6427	2.3	(1,2,2)
24.86	3.5819	4.4	(0,2,3)
25.22	3.5314	7.1	(1,1,4)
25.60	3.4799	1.3	(2,1,2)
28.45	3.1378	62.2	(0,2,4)
28.90	3.0897	100.0	(2,2,0)
29.71	3.0074	2.0	(1,1,5)
29.79	2.9990	79.8	(2,0,4)
30.43	2.9378	5.7	(1,2,4)
30.75	2.9080	5.1	(2,2,2)
31.05	2.8804	4.1	(0,3,2)
31.15	2.8710	5.9	(1,3,0)

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Energy Properties

Formation Energy/atom

-1.65265

eV/atom

Energy/atom

-5.74943

eV/atom

Energy above Hull

0.0000

eV/atom

Uncorrected Energy

-5.3857

eV/atom

Volume/atom

19.41

Å³

c/a Ratio

2.0582

Electronic Properties

Metallic

Metal

Band Gap

Direct Gap

CBM

N/A

Magnetic Properties

Magnetic

Yes

Total Mag. Moment

7.2288

μB

Mag. Ordering

FiM

Mag. Sites

Magnetization/Volume

0.005480

μB/Å³

Elastic Properties

Elastic data not available

Feature Analysis

Composition Overview

Element Composition (atomic fraction)

Composition Info

Major / Matrix Element

O · 0.529

Element Family

Metalloid-Nonmetal

Solute Fraction

0.471

Interstitial Fraction

0.000

High-Entropy Alloy Features

Composite Radar (normalized)

Element-Class Share

Mix Entropy ΔS/R

1.1151

HEA criterion (>1.0 = high entropy)

Mix Entropy ΔS

9.2707

J/mol·K

Ω Parameter

0.0000

Ω > 1.1 favors solid solution

Atomic Size Mismatch δr

60.568%

δr < 6.6% favors single-phase solid solution

Electronegativity Diff Δχ

1.2095

smaller = more stable mixing

VEC

3.412

valence electron concentration, affects phase stability

Mix Enthalpy ΔH_mix

0.000

kJ/mol; negative = exothermic mixing

Entropy Norm

0.8044

SS Former

Phase Tendency

Related Tasks

Related computation task IDs (1)

aaacxszw

Citation & References

Materials Project Page

https://materialsproject.org/materials/mp-654335

Reference Citation

The crystal structure and related material properties of CsK5Ru2O9 were obtained from the Materials Project database (MP-ID: mp-654335, 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_CsK5Ru2O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.36327800
_cell_length_b   9.17014700
_cell_length_c   17.21324900
_cell_angle_alpha   90.00000000
_cell_angle_beta   90.00000000
_cell_angle_gamma   90.00000000
_symmetry_Int_Tables_number   1
_chemical_formula_structural   CsK5Ru2O9
_chemical_formula_sum   'Cs4 K20 Ru8 O36'
_cell_volume   1320.12690377
_cell_formula_units_Z   4
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
  Cs  Cs0  1  0.25000000  0.75316800  0.27226400  1.0
  Cs  Cs1  1  0.25000000  0.74683200  0.77226400  1.0
  Cs  Cs2  1  0.75000000  0.24683200  0.72773600  1.0
  Cs  Cs3  1  0.75000000  0.25316800  0.22773600  1.0
  K  K4  1  0.98948700  0.02239000  0.39647900  1.0
  K  K5  1  0.98948700  0.47761000  0.89647900  1.0
  K  K6  1  0.51051300  0.47761000  0.89647900  1.0
  K  K7  1  0.99614400  0.96524200  0.10231800  1.0
  K  K8  1  0.48948700  0.97761000  0.60352100  1.0
  K  K9  1  0.75000000  0.74752800  0.97702600  1.0
  K  K10  1  0.25000000  0.24752800  0.52297400  1.0
  K  K11  1  0.48948700  0.52239000  0.10352100  1.0
  K  K12  1  0.00385600  0.46524200  0.39768200  1.0
  K  K13  1  0.50385600  0.53475800  0.60231800  1.0
  K  K14  1  0.51051300  0.02239000  0.39647900  1.0
  K  K15  1  0.99614400  0.53475800  0.60231800  1.0
  K  K16  1  0.01051300  0.97761000  0.60352100  1.0
  K  K17  1  0.25000000  0.25247200  0.02297400  1.0
  K  K18  1  0.49614400  0.03475800  0.89768200  1.0
  K  K19  1  0.00385600  0.03475800  0.89768200  1.0
  K  K20  1  0.49614400  0.46524200  0.39768200  1.0
  K  K21  1  0.75000000  0.75247200  0.47702600  1.0
  K  K22  1  0.01051300  0.52239000  0.10352100  1.0
  K  K23  1  0.50385600  0.96524200  0.10231800  1.0
  Ru  Ru24  1  0.75000000  0.24880200  0.00569700  1.0
  Ru  Ru25  1  0.75000000  0.25119800  0.50569700  1.0
  Ru  Ru26  1  0.25000000  0.29514500  0.75521400  1.0
  Ru  Ru27  1  0.75000000  0.79514500  0.74478600  1.0
  Ru  Ru28  1  0.25000000  0.20485500  0.25521400  1.0
  Ru  Ru29  1  0.25000000  0.75119800  0.99430300  1.0
  Ru  Ru30  1  0.75000000  0.70485500  0.24478600  1.0
  Ru  Ru31  1  0.25000000  0.74880200  0.49430300  1.0
  O  O32  1  0.43985300  0.75382100  0.94204200  1.0
  O  O33  1  0.25000000  0.53811400  0.99137100  1.0
  O  O34  1  0.93985300  0.25382100  0.55795800  1.0
  O  O35  1  0.25000000  0.23475000  0.85623100  1.0
  O  O36  1  0.42222700  0.08546300  0.24375000  1.0
  O  O37  1  0.56014700  0.24617900  0.05795800  1.0
  O  O38  1  0.75000000  0.03529300  0.00219600  1.0
  O  O39  1  0.25000000  0.26525000  0.35623100  1.0
  O  O40  1  0.06014700  0.75382100  0.94204200  1.0
  O  O41  1  0.75000000  0.25376000  0.89913500  1.0
  O  O42  1  0.25000000  0.53529300  0.49780400  1.0
  O  O43  1  0.25000000  0.96470700  0.99780400  1.0
  O  O44  1  0.93985300  0.24617900  0.05795800  1.0
  O  O45  1  0.07777300  0.41453700  0.74375000  1.0
  O  O46  1  0.92222700  0.58546300  0.25625000  1.0
  O  O47  1  0.75000000  0.64624000  0.81232500  1.0
  O  O48  1  0.75000000  0.46470700  0.50219600  1.0
  O  O49  1  0.25000000  0.96188600  0.49137100  1.0
  O  O50  1  0.75000000  0.03811400  0.50862900  1.0
  O  O51  1  0.43985300  0.74617900  0.44204200  1.0
  O  O52  1  0.75000000  0.73475000  0.64376900  1.0
  O  O53  1  0.57777300  0.58546300  0.25625000  1.0
  O  O54  1  0.75000000  0.24624000  0.39913500  1.0
  O  O55  1  0.75000000  0.76525000  0.14376900  1.0
  O  O56  1  0.57777300  0.91453700  0.75625000  1.0
  O  O57  1  0.75000000  0.46188600  0.00862900  1.0
  O  O58  1  0.25000000  0.35376000  0.18767500  1.0
  O  O59  1  0.07777300  0.08546300  0.24375000  1.0
  O  O60  1  0.92222700  0.91453700  0.75625000  1.0
  O  O61  1  0.25000000  0.75376000  0.60086500  1.0
  O  O62  1  0.25000000  0.74624000  0.10086500  1.0
  O  O63  1  0.25000000  0.14624000  0.68767500  1.0
  O  O64  1  0.56014700  0.25382100  0.55795800  1.0
  O  O65  1  0.06014700  0.74617900  0.44204200  1.0
  O  O66  1  0.75000000  0.85376000  0.31232500  1.0
  O  O67  1  0.42222700  0.41453700  0.74375000  1.0

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