Na8Si7O18

High-Entropy Materials HEA Traditional Materials TRA

MP-ID: mp-652025 · Space group: P1 (#1)

Materials Project API

Basic Information

Formula

Na8Si7O18

MP-ID

mp-652025

Elements

Sites

Density

1.9571

g/cm³

Volume

567.21

Å³

Cell a

6.2781

Cell b

9.0687

Cell c

10.9707

α Angle

103.33

β Angle

101.12

γ Angle

104.51

Space Group

Point Group

Crystal System

Triclinic

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
10.54	8.3928	100.0	(0,1,0)
15.12	5.8590	44.1	(1,0,0)
15.28	5.7976	35.7	(1,0,-1)
15.46	5.7320	2.3	(0,1,1)
15.54	5.7015	24.0	(1,-1,0)
17.23	5.1454	3.8	(0,0,2)
17.33	5.1178	35.3	(1,-1,-1)
17.37	5.1048	36.7	(0,1,-2)
18.23	4.8661	5.0	(1,-1,1)
19.32	4.5933	2.5	(1,0,1)
19.70	4.5057	1.5	(1,0,-2)
19.80	4.4849	19.6	(1,1,-1)
20.37	4.3587	7.0	(0,2,-1)
21.00	4.2298	13.6	(1,1,0)
21.17	4.1964	5.4	(0,2,0)
21.91	4.0560	4.5	(1,-2,0)
22.58	3.9380	3.7	(1,-1,-2)
22.75	3.9085	3.5	(1,-2,1)
22.77	3.9055	5.7	(0,1,2)
23.09	3.8527	1.9	(0,2,-2)
23.98	3.7117	2.3	(1,-1,2)
24.38	3.6515	4.6	(1,-2,-1)
25.00	3.5625	1.3	(0,1,-3)
25.16	3.5394	7.0	(0,2,1)

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Energy Properties

Formation Energy/atom

-1.89400

eV/atom

Energy/atom

-6.06898

eV/atom

Energy above Hull

0.9707

eV/atom

Uncorrected Energy

-5.9812

eV/atom

Volume/atom

17.19

Å³

c/a Ratio

1.7474

Electronic Properties

Metallic

Metal

Band Gap

Direct Gap

CBM

N/A

Magnetic Properties

Magnetic

Total Mag. Moment

0.5552

μB

Mag. Ordering

Mag. Sites

Magnetization/Volume

0.000980

μB/Å³

Elastic Properties

Elastic data not available

Feature Analysis

Composition Overview

Element Composition (atomic fraction)

Composition Info

Major / Matrix Element

O · 0.545

Element Family

Metalloid-Nonmetal

Solute Fraction

0.455

Interstitial Fraction

0.212

High-Entropy Alloy Features

Composite Radar (normalized)

Element-Class Share

Mix Entropy ΔS/R

1.0031

HEA criterion (>1.0 = high entropy)

Mix Entropy ΔS

8.3395

J/mol·K

Ω Parameter

0.5433

Ω > 1.1 favors solid solution

Atomic Size Mismatch δr

50.814%

δr < 6.6% favors single-phase solid solution

Electronegativity Diff Δχ

1.0751

smaller = more stable mixing

VEC

3.273

valence electron concentration, affects phase stability

Mix Enthalpy ΔH_mix

-7.332

kJ/mol; negative = exothermic mixing

Entropy Norm

0.9130

SS Former

Phase Tendency

Traditional Material Features

ROM Blended-Feature Radar

Rating & Classification

Tier

Score

0.294

Family

Interstitial Alloy

Matrix Element

O · 0.545

Related Tasks

Related computation task IDs (1)

aaaecota

Citation & References

Materials Project Page

https://materialsproject.org/materials/mp-652025

Reference Citation

The crystal structure and related material properties of Na8Si7O18 were obtained from the Materials Project database (MP-ID: mp-652025, 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_Na8Si7O18
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.27812200
_cell_length_b   9.06869643
_cell_length_c   10.97065986
_cell_angle_alpha   103.32741023
_cell_angle_beta   101.11638746
_cell_angle_gamma   104.50908253
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Na8Si7O18
_chemical_formula_sum   'Na8 Si7 O18'
_cell_volume   567.20898650
_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
  Na  Na0  1  0.27159800  0.70438900  0.26324100  1.0
  Na  Na1  1  0.58254400  0.31138700  0.72361900  1.0
  Na  Na2  1  0.46585000  0.54908900  0.96568300  1.0
  Na  Na3  1  0.94708400  0.87337500  0.46320700  1.0
  Na  Na4  1  0.40438100  0.48456800  0.47960300  1.0
  Na  Na5  1  0.96016100  0.43516100  0.99096900  1.0
  Na  Na6  1  0.57822500  0.11001800  0.48496700  1.0
  Na  Na7  1  0.91997000  0.56709800  0.54871000  1.0
  Si  Si8  1  0.97185200  0.01950100  0.01125400  1.0
  Si  Si9  1  0.94083900  0.69066000  0.85574200  1.0
  Si  Si10  1  0.79022000  0.54022700  0.26466700  1.0
  Si  Si11  1  0.12031700  0.08877200  0.25790700  1.0
  Si  Si12  1  0.34888200  0.33395000  0.15414000  1.0
  Si  Si13  1  0.09631200  0.36515300  0.68557500  1.0
  Si  Si14  1  0.78528600  0.93211600  0.75181700  1.0
  O  O15  1  0.28709200  0.48455900  0.12954200  1.0
  O  O16  1  0.87940000  0.63603400  0.17012000  1.0
  O  O17  1  0.70737900  0.96341900  0.61847100  1.0
  O  O18  1  0.75506400  0.54382900  0.86384500  1.0
  O  O19  1  0.12451000  0.33118900  0.82464400  1.0
  O  O20  1  0.20424400  0.99539500  0.35213700  1.0
  O  O21  1  0.26021700  0.31255400  0.59753800  1.0
  O  O22  1  0.19959800  0.16702000  0.03175000  1.0
  O  O23  1  0.83562800  0.33519500  0.60208000  1.0
  O  O24  1  0.68904700  0.62266000  0.37892000  1.0
  O  O25  1  0.02061000  0.84792100  0.98649700  1.0
  O  O26  1  0.17114300  0.62999700  0.43312900  1.0
  O  O27  1  0.00470500  0.47945000  0.34407700  1.0
  O  O28  1  0.61976900  0.35206100  0.17524600  1.0
  O  O29  1  0.28870800  0.26964200  0.28193600  1.0
  O  O30  1  0.21670200  0.58147000  0.72426100  1.0
  O  O31  1  0.20335500  0.67915700  0.85236800  1.0
  O  O32  1  0.84930900  0.76298400  0.73233500  1.0

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