Ca9Mg(PO4)7

High-Entropy Materials HEA

MP-ID: mp-728486 · Space group: R3c (#161)

Materials Project API

Basic Information

Formula

Ca9Mg(PO4)7

MP-ID

mp-728486

Elements

Sites

Density

2.9567

g/cm³

Volume

1,179.20

Å³

Cell a

13.8584

Cell b

13.8584

Cell c

13.8584

α Angle

44.28

β Angle

44.28

γ Angle

44.28

Space Group

R3c

Point Group

Crystal System

Trigonal

Bravais Lattice

Trigonal R

Stability

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
10.86	8.1452	8.5	(1,1,0)
13.61	6.5043	13.1	(2,1,1)
16.98	5.2233	47.4	(1,0,-1)
20.20	4.3969	4.2	(2,0,0)
21.38	4.1560	1.7	(3,3,2)
21.82	4.0726	15.2	(2,2,0)
22.20	4.0049	2.7	(3,2,1)
25.76	3.4588	39.5	(4,3,3)
26.17	3.4052	3.7	(2,0,-1)
26.50	3.3637	9.8	(2,1,-1)
27.41	3.2536	3.0	(4,3,2)
27.42	3.2522	1.7	(4,2,2)
27.78	3.2117	57.5	(3,1,0)
29.62	3.0156	11.7	(2,-1,-1)
31.01	2.8838	100.0	(4,4,2)
32.43	2.7608	18.0	(4,3,1)
32.99	2.7151	7.5	(3,3,0)
33.46	2.6781	3.5	(5,4,3)
34.34	2.6116	73.8	(2,0,-2)
35.00	2.5641	3.9	(5,5,4)
35.11	2.5562	5.0	(3,1,-1)
35.56	2.5246	14.3	(5,3,2)
35.87	2.5036	2.9	(2,1,-2)
37.10	2.4236	3.5	(3,2,-1)

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Energy Properties

Formation Energy/atom

-3.24754

eV/atom

Energy/atom

-7.60603

eV/atom

Energy above Hull

0.0084

eV/atom

Uncorrected Energy

-7.1786

eV/atom

Volume/atom

13.10

Å³

c/a Ratio

1.0000

Electronic Properties

Metallic

Metal

Band Gap

Direct Gap

CBM

N/A

Magnetic Properties

Magnetic

Yes

Total Mag. Moment

2.0008

μB

Mag. Ordering

Mag. Sites

Magnetization/Volume

0.001700

μB/Å³

Elastic Properties

Elastic data not available

Feature Analysis

Composition Overview

Element Composition (atomic fraction)

Composition Info

Major / Matrix Element

O · 0.622

Element Family

Metalloid-Nonmetal

Solute Fraction

0.378

Interstitial Fraction

0.156

High-Entropy Alloy Features

Composite Radar (normalized)

Element-Class Share

Mix Entropy ΔS/R

0.9911

HEA criterion (>1.0 = high entropy)

Mix Entropy ΔS

8.2404

J/mol·K

Ω Parameter

0.2020

Ω > 1.1 favors solid solution

Atomic Size Mismatch δr

55.916%

δr < 6.6% favors single-phase solid solution

Electronegativity Diff Δχ

1.0010

smaller = more stable mixing

VEC

3.711

valence electron concentration, affects phase stability

Mix Enthalpy ΔH_mix

-13.342

kJ/mol; negative = exothermic mixing

Entropy Norm

0.7150

SS Former

Phase Tendency

Related Tasks

Related computation task IDs (1)

aaabplqs

Citation & References

Materials Project Page

https://materialsproject.org/materials/mp-728486

Reference Citation

The crystal structure and related material properties of Ca9Mg(PO4)7 were obtained from the Materials Project database (MP-ID: mp-728486, 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_Ca9Mg(PO4)7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.85841198
_cell_length_b   13.85841198
_cell_length_c   13.85841197
_cell_angle_alpha   44.28371451
_cell_angle_beta   44.28371451
_cell_angle_gamma   44.28371610
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ca9Mg(PO4)7
_chemical_formula_sum   'Ca18 Mg2 P14 O56'
_cell_volume   1179.19988227
_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  0.03425100  0.46911300  0.01228800  1.0
  Ca  Ca1  1  0.46911300  0.01228800  0.03425100  1.0
  Ca  Ca2  1  0.01228800  0.03425100  0.46911300  1.0
  Ca  Ca3  1  0.53425100  0.51228800  0.96911300  1.0
  Ca  Ca4  1  0.51228800  0.96911300  0.53425100  1.0
  Ca  Ca5  1  0.96911300  0.53425100  0.51228800  1.0
  Ca  Ca6  1  0.93074500  0.34575300  0.91803700  1.0
  Ca  Ca7  1  0.34575300  0.91803700  0.93074500  1.0
  Ca  Ca8  1  0.91803700  0.93074500  0.34575300  1.0
  Ca  Ca9  1  0.43074500  0.41803700  0.84575300  1.0
  Ca  Ca10  1  0.41803700  0.84575300  0.43074500  1.0
  Ca  Ca11  1  0.84575300  0.43074500  0.41803700  1.0
  Ca  Ca12  1  0.06001700  0.65525700  0.08839100  1.0
  Ca  Ca13  1  0.65525700  0.08839100  0.06001700  1.0
  Ca  Ca14  1  0.08839100  0.06001700  0.65525700  1.0
  Ca  Ca15  1  0.56001700  0.58839100  0.15525700  1.0
  Ca  Ca16  1  0.58839100  0.15525700  0.56001700  1.0
  Ca  Ca17  1  0.15525700  0.56001700  0.58839100  1.0
  Mg  Mg18  1  0.49987800  0.49987800  0.49987800  1.0
  Mg  Mg19  1  0.99987800  0.99987800  0.99987800  1.0
  P  P20  1  0.25379700  0.25379700  0.25379700  1.0
  P  P21  1  0.75379700  0.75379700  0.75379700  1.0
  P  P22  1  0.18963300  0.68148800  0.22086300  1.0
  P  P23  1  0.68148800  0.22086300  0.18963300  1.0
  P  P24  1  0.22086300  0.18963300  0.68148800  1.0
  P  P25  1  0.68963300  0.72086300  0.18148800  1.0
  P  P26  1  0.72086300  0.18148800  0.68963300  1.0
  P  P27  1  0.18148800  0.68963300  0.72086300  1.0
  P  P28  1  0.27386100  0.81868500  0.30930600  1.0
  P  P29  1  0.81868500  0.30930600  0.27386100  1.0
  P  P30  1  0.30930600  0.27386100  0.81868500  1.0
  P  P31  1  0.77386100  0.80930600  0.31868500  1.0
  P  P32  1  0.80930600  0.31868500  0.77386100  1.0
  P  P33  1  0.31868500  0.77386100  0.80930600  1.0
  O  O34  1  0.29542500  0.29542500  0.29542500  1.0
  O  O35  1  0.79542500  0.79542500  0.79542500  1.0
  O  O36  1  0.39132900  0.21918500  0.11120900  1.0
  O  O37  1  0.21918500  0.11120900  0.39132900  1.0
  O  O38  1  0.11120900  0.39132900  0.21918500  1.0
  O  O39  1  0.89132900  0.61120900  0.71918500  1.0
  O  O40  1  0.61120900  0.71918500  0.89132900  1.0
  O  O41  1  0.71918500  0.89132900  0.61120900  1.0
  O  O42  1  0.13875900  0.60229000  0.23361700  1.0
  O  O43  1  0.60229000  0.23361700  0.13875900  1.0
  O  O44  1  0.23361700  0.13875900  0.60229000  1.0
  O  O45  1  0.63875900  0.73361700  0.10229000  1.0
  O  O46  1  0.73361700  0.10229000  0.63875900  1.0
  O  O47  1  0.10229000  0.63875900  0.73361700  1.0
  O  O48  1  0.36392900  0.62453200  0.14359900  1.0
  O  O49  1  0.62453200  0.14359900  0.36392900  1.0
  O  O50  1  0.14359900  0.36392900  0.62453200  1.0
  O  O51  1  0.86392900  0.64359900  0.12453200  1.0
  O  O52  1  0.64359900  0.12453200  0.86392900  1.0
  O  O53  1  0.12453200  0.86392900  0.64359900  1.0
  O  O54  1  0.11501600  0.65985700  0.38506800  1.0
  O  O55  1  0.65985700  0.38506800  0.11501600  1.0
  O  O56  1  0.38506800  0.11501600  0.65985700  1.0
  O  O57  1  0.61501600  0.88506800  0.15985700  1.0
  O  O58  1  0.88506800  0.15985700  0.61501600  1.0
  O  O59  1  0.15985700  0.61501600  0.88506800  1.0
  O  O60  1  0.12134000  0.85828700  0.12611500  1.0
  O  O61  1  0.85828700  0.12611500  0.12134000  1.0
  O  O62  1  0.12611500  0.12134000  0.85828700  1.0
  O  O63  1  0.62134000  0.62611500  0.35828700  1.0
  O  O64  1  0.62611500  0.35828700  0.62134000  1.0
  O  O65  1  0.35828700  0.62134000  0.62611500  1.0
  O  O66  1  0.29811000  0.91395200  0.30788800  1.0
  O  O67  1  0.91395200  0.30788800  0.29811000  1.0
  O  O68  1  0.30788800  0.29811000  0.91395200  1.0
  O  O69  1  0.79811000  0.80788800  0.41395200  1.0
  O  O70  1  0.80788800  0.41395200  0.79811000  1.0
  O  O71  1  0.41395200  0.79811000  0.80788800  1.0
  O  O72  1  0.10196000  0.85343000  0.40604600  1.0
  O  O73  1  0.85343000  0.40604600  0.10196000  1.0
  O  O74  1  0.40604600  0.10196000  0.85343000  1.0
  O  O75  1  0.60196000  0.90604600  0.35343000  1.0
  O  O76  1  0.90604600  0.35343000  0.60196000  1.0
  O  O77  1  0.35343000  0.60196000  0.90604600  1.0
  O  O78  1  0.33465900  0.86117700  0.14222300  1.0
  O  O79  1  0.86117700  0.14222300  0.33465900  1.0
  O  O80  1  0.14222300  0.33465900  0.86117700  1.0
  O  O81  1  0.83465900  0.64222300  0.36117700  1.0
  O  O82  1  0.64222300  0.36117700  0.83465900  1.0
  O  O83  1  0.36117700  0.83465900  0.64222300  1.0
  O  O84  1  0.36423300  0.64266100  0.38564200  1.0
  O  O85  1  0.64266100  0.38564200  0.36423300  1.0
  O  O86  1  0.38564200  0.36423300  0.64266100  1.0
  O  O87  1  0.86423300  0.88564200  0.14266100  1.0
  O  O88  1  0.88564200  0.14266100  0.86423300  1.0
  O  O89  1  0.14266100  0.86423300  0.88564200  1.0

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