Mn–O phases

16 phases (tier A 9, tier C 2, liquid 2, gas 2, needs_review 1); 15 stable in a calculated diagram. Structure types are assigned only when the stored evidence supports an assignment under the stated tier rules (tier A: standard phase name; tier B: unique Materials Project + OQMD on-hull match, DFT-supported; tier C: one structure stated by the assessment's crystallographic table, assessor-stated); other phases list candidates and are marked needs_review. Stability is from phase diagrams calculated with pycalphad from the SGTE binary collection (evidence class: model).

Data: interactive registry · full JSON · Mn–O system page · Markdown · field reference

Phases of the Mn–O system (16)
Phase	Structure	Basis	Stability (calculated)	Literature values	TDB models
B1_OXIDE phase:mn-o:b1-oxide	NaCl · B1 · cF8 · Fm-3m (225)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 300–2123.45 K, x(O) 0.5–0.53321	80	2
BCC_A2 phase:mn-o:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 1411.01–1518.46 K, x(O) 0–0	5	2
CBCC_A12 phase:mn-o:cbcc-a12	alpha-Mn · A12 · cI58 · I-43m (217)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 300–980 K, x(O) 0–0	7	2
CUB_A13 phase:mn-o:cub-a13	beta-Mn · A13 · cP20 · P4_132 (213)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 980–1359.99 K, x(O) 0–0	9	2
FCC_A1 phase:mn-o:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 1359.99–1503.51 K, x(O) 0–0	5	2
GAS phase:mn-o:gas	gas	gas	stable in 2 of 2 calculated diagram(s): 1158.26–2500 K, x(O) 0–1	0	2
SPINEL_H11 phase:mn-o:h11-spinel	Al2MgO4 · H1_1 · cF56 · Fd-3m (227)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	stable in 1 of 1 calculated diagram(s): 1408.45–1878.72 K, x(O) 0.57123–0.5716	0	1
HCP_A3 phase:mn-o:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	not stable in 2 calculated diagram(s)	0	2
ION phase:mn-o:ion	liquid	liquid	stable in 2 of 2 calculated diagram(s): 1518.46–2500 K, x(O) 0–0.55266	0	2
LIQUID phase:mn-o:liquid	liquid	liquid	stable in 1 of 2 calculated diagram(s): 1503.51–1503.51 K, x(O) 0–0	35	2
MN2O3_D53 phase:mn-o:mn2o3-d53	Mn2O3 · D5_3 · cI80 · Ia-3 (206)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 300–1237.26 K, x(O) 0.6–0.6	55	2
MN3O4_A phase:mn-o:mn3o4-a		needs_review	stable in 1 of 1 calculated diagram(s): 300–1505 K, x(O) 0.57128–0.57161	0	1
MN3O4_ALPHA phase:mn-o:mn3o4-alpha	Mn3O4 · tI28 · I4_1/amd (141)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	stable in 1 of 1 calculated diagram(s): 300–1442.97 K, x(O) 0.57143–0.57143	45	1
MN3O4_H11 phase:mn-o:mn3o4-h11	Al2MgO4 · H1_1 · cF56 · Fd-3m (227)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 1442.97–1882.41 K, x(O) 0.57143–0.57143	38	1
MNO2_C4 phase:mn-o:mno2-c4	TiO2 · C4 · tP6 · P4_2/mnm (136)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 300–485 K, x(O) 0.66667–0.66667	50	2
O2GAS phase:mn-o:o2gas	gas	gas	stable in 2 of 2 calculated diagram(s): 300–485 K, x(O) 1–1	0	2

B1_OXIDE (Mn–O)

Id: phase:mn-o:b1-oxide; status assigned
Structure: NaCl · B1 · cF8 · Fm-3m (225); type st:b1-nacl-cf8; tier A: standard phase name; confidence high
Stability: stable in 2 of 2 calculated diagram(s): 300–2123.45 K, x(O) 0.5–0.53321
Literature: 80 values (80 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:mn-o:b1-oxide
paper: paper:10.1007/s11669-003-0004-6:MnO
tdb: tdb:MnO-03Gru-LB.tdb:B1_OXIDE, tdb:MnO-10Kje.tdb:B1_OXIDE

TDB models of B1_OXIDE (2): PHASE and CONSTITUENT statements as written

MnO-03Gru-LB.tdb: B1_OXIDE, type code %, sha256 2f59cdf668abb9e9…

84: PHASE B1_OXIDE:I % 2 1 1 !
85: CONST B1_OXIDE:I : MN+2% MN+3 VA : O-2 : !

MnO-10Kje.tdb: B1_OXIDE, type code %, sha256 bd1f5b2a6c1bd76e…

78: PHASE B1_OXIDE:I % 2 1 1 !
79: CONST B1_OXIDE:I : MN+2% MN+3 VA : O-2 : !

Example references (10 of 13; assessments first):

doi:10.1007/s11669-003-0004-6 A. Nicholas Grundy, Bengt Hallstedt, Ludwig J. Gauckler, Assessment of the Mn-O system, JPE 24, 21-39 (2003).
assessment that models this phase; reports values for this phase
doi:10.1007/s11669-009-9643-6 Lina Kjellqvist, Malin Selleby, Thermodynamic Assessment of the Fe-Mn-O System, J. Phase Equilib. Diffus. 31, 113-134 (2010).
assessment that models this phase
doi:10.1016/0013-4686(67)85035-7 C.B. Alcock, S. Zador, Thermodynamic study of the manganese/ manganous-oxide system by the use of solid oxide electrolytes, Electrochimica Acta 12, 673-677 (1967).
cited as the source of values for this phase
doi:10.1149/1.2411434 G. G. Charette, S. N. Flengas, Thermodynamic Properties of the Oxides of Fe, Ni, Pb, Cu, and Mn, by EMF Measurements, J. Electrochem. Soc. 115, 796 (1968).
cited as the source of values for this phase
doi:10.1149/1.2426584 A. Z. Hed, D. S. Tannhauser, Contribution to the Mn-O Phase Diagram at High Temperature, J. Electrochem. Soc. 114, 314 (1967).
cited as the source of values for this phase
doi:10.1002/srin.196904332 Norbert G. Schmahl, Detlev F. K. Hennings, Das Zustandsdiagramm Mn3 O4 -MnO und die in ihm auftretenden Zersetzungsdrücke, Archiv für das Eisenhüttenwesen 40, 395-399 (1969).
cited as the source of values for this phase
doi:10.2475/ajs.258.1.66 W. C. Hahn, A. Muan, Studies in the system Mn-O--The Mn 2 O 3 -Mn 3 O 4 and Mn 3 O 4 -MnO equilibria, American Journal of Science 258, 66-78 (1960).
cited as the source of values for this phase
doi:10.1002/srin.196402318 Hermann Schenck, Martin G. Frohberg, Reginald Nünninghoff, Das System MnO(–FeO)–MgO(–CaO) und seine Verteilungsgleichgewichte mit flüssigem Mangan und Eisen‐Mangan‐Legierungen, Steel Research Intl 35, 269-277 (1964).
cited as the source of values for this phase
doi:10.1002/srin.198405356 Eberhard Schürmann, Norbert Bannenberg, Metall-Schlackengleichgewichte im System Eisen-Mangan-Schwefel-Sauerstoff als Grundlage der Mangandesoxidation von Stahlschmelzen bei gleichzeitiger Anwesenheit von Schwefel, Archiv für das Eisenhüttenwesen 55, 349-358 (1984).
cited as the source of values for this phase
doi:10.1007/bf01046534 H.S. O’Neill and M.I. Pownceby: “Thermodynamic Data From the Redox Reactions at High Temperatures. I. An Experimental and Theoretical Assessment of the Electrochemical Method Using Stabilized Zirconia Electrolytes, With Revised Values for the Fe-⬘FeO⬘, Co-CoO, Ni-NiO and Cu-Cu2O Oxygen Buffers and New Data for the W-WO2 Buffer,” Contrib. Mineral. Petrol., 1993, 114, pp. 296-314.
cited as the source of values for this phase

BCC_A2 (Mn–O)

Id: phase:mn-o:bcc-a2; status assigned
Structure: W · A2 · cI2 · Im-3m (229); type st:a2-w-ci2; tier A: standard phase name; confidence high
Stability: stable in 2 of 2 calculated diagram(s): 1411.01–1518.46 K, x(O) 0–0
Literature: 5 values (5 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:mn-o:bcc-a2
paper: paper:10.1007/s11669-003-0004-6:δ-Mn
tdb: tdb:MnO-03Gru-LB.tdb:BCC_A2, tdb:MnO-10Kje.tdb:BCC_A2

TDB models of BCC_A2 (2): PHASE and CONSTITUENT statements as written

MnO-03Gru-LB.tdb: BCC_A2, type code %B, sha256 2f59cdf668abb9e9…

64: PHASE BCC_A2 %B 2 1 3 !
65: CONST BCC_A2 : MN : O VA : !

MnO-10Kje.tdb: BCC_A2, type code %B, sha256 bd1f5b2a6c1bd76e…

57: PHASE BCC_A2 %B 2 1 3 !
58: CONST BCC_A2 : MN : VA : !

Example references (2 of 2; assessments first):

doi:10.1007/s11669-003-0004-6 A. Nicholas Grundy, Bengt Hallstedt, Ludwig J. Gauckler, Assessment of the Mn-O system, JPE 24, 21-39 (2003).
assessment that models this phase; reports values for this phase
doi:10.1007/s11669-009-9643-6 Lina Kjellqvist, Malin Selleby, Thermodynamic Assessment of the Fe-Mn-O System, J. Phase Equilib. Diffus. 31, 113-134 (2010).
assessment that models this phase

CBCC_A12 (Mn–O)

Id: phase:mn-o:cbcc-a12; status assigned
Structure: alpha-Mn · A12 · cI58 · I-43m (217); type st:a12-alpha-mn-ci58; tier A: standard phase name; confidence high
Stoichiometry: Mn 1.0000
Stability: stable in 2 of 2 calculated diagram(s): 300–980 K, x(O) 0–0
Literature: 7 values (7 accepted) from 1 papers
Interactive: phase registry entry

Names (5): corpus: corpus:phase:mn-o:cbcc-a12
paper: paper:10.1007/s11669-003-0004-6:Mn, paper:10.1007/s11669-003-0004-6:α-Mn
tdb: tdb:MnO-03Gru-LB.tdb:CBCC_A12, tdb:MnO-10Kje.tdb:CBCC_A12

TDB models of CBCC_A12 (2): PHASE and CONSTITUENT statements as written

MnO-03Gru-LB.tdb: CBCC_A12, type code %A, sha256 2f59cdf668abb9e9…

74: PHASE CBCC_A12 %A 2 1 1 !
75: CONST CBCC_A12 : MN : VA : !

MnO-10Kje.tdb: CBCC_A12, type code %A, sha256 bd1f5b2a6c1bd76e…

67: PHASE CBCC_A12 %A 2 1 1 !
68: CONST CBCC_A12 : MN : VA : !

Example references (3 of 3; assessments first):

doi:10.1007/s11669-003-0004-6 A. Nicholas Grundy, Bengt Hallstedt, Ludwig J. Gauckler, Assessment of the Mn-O system, JPE 24, 21-39 (2003).
assessment that models this phase; reports values for this phase
doi:10.1007/s11669-009-9643-6 Lina Kjellqvist, Malin Selleby, Thermodynamic Assessment of the Fe-Mn-O System, J. Phase Equilib. Diffus. 31, 113-134 (2010).
assessment that models this phase
doi:10.1002/srin.196402318 Hermann Schenck, Martin G. Frohberg, Reginald Nünninghoff, Das System MnO(–FeO)–MgO(–CaO) und seine Verteilungsgleichgewichte mit flüssigem Mangan und Eisen‐Mangan‐Legierungen, Steel Research Intl 35, 269-277 (1964).
cited as the source of values for this phase

CUB_A13 (Mn–O)

Id: phase:mn-o:cub-a13; status assigned
Structure: beta-Mn · A13 · cP20 · P4_132 (213); type st:a13-beta-mn-cp20; tier A: standard phase name; confidence high
Stoichiometry: Mn 1.0000
Stability: stable in 2 of 2 calculated diagram(s): 980–1359.99 K, x(O) 0–0
Literature: 9 values (9 accepted) from 1 papers
Interactive: phase registry entry

Names (5): corpus: corpus:phase:mn-o:cub-a13
paper: paper:10.1007/s11669-003-0004-6:β-, γ-, δ-Mn, paper:10.1007/s11669-003-0004-6:β-Mn
tdb: tdb:MnO-03Gru-LB.tdb:CUB_A13, tdb:MnO-10Kje.tdb:CUB_A13

TDB models of CUB_A13 (2): PHASE and CONSTITUENT statements as written

MnO-03Gru-LB.tdb: CUB_A13, type code %, sha256 2f59cdf668abb9e9…

79: PHASE CUB_A13 % 2 1 1 !
80: CONST CUB_A13 : MN : VA : !

MnO-10Kje.tdb: CUB_A13, type code %, sha256 bd1f5b2a6c1bd76e…

72: PHASE CUB_A13 % 2 1 1 !
73: CONST CUB_A13 : MN : VA : !

Example references (3 of 3; assessments first):

doi:10.1007/s11669-003-0004-6 A. Nicholas Grundy, Bengt Hallstedt, Ludwig J. Gauckler, Assessment of the Mn-O system, JPE 24, 21-39 (2003).
assessment that models this phase; reports values for this phase
doi:10.1007/s11669-009-9643-6 Lina Kjellqvist, Malin Selleby, Thermodynamic Assessment of the Fe-Mn-O System, J. Phase Equilib. Diffus. 31, 113-134 (2010).
assessment that models this phase
doi:10.1016/0013-4686(67)85035-7 C.B. Alcock, S. Zador, Thermodynamic study of the manganese/ manganous-oxide system by the use of solid oxide electrolytes, Electrochimica Acta 12, 673-677 (1967).
cited as the source of values for this phase

FCC_A1 (Mn–O)

Id: phase:mn-o:fcc-a1; status assigned
Structure: Cu · A1 · cF4 · Fm-3m (225); type st:a1-cu-cf4; tier A: standard phase name; confidence high
Stoichiometry: Mn 1.0000
Stability: stable in 2 of 2 calculated diagram(s): 1359.99–1503.51 K, x(O) 0–0
Literature: 5 values (5 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:mn-o:fcc-a1
paper: paper:10.1007/s11669-003-0004-6:γ-Mn
tdb: tdb:MnO-03Gru-LB.tdb:FCC_A1, tdb:MnO-10Kje.tdb:FCC_A1

TDB models of FCC_A1 (2): PHASE and CONSTITUENT statements as written

MnO-03Gru-LB.tdb: FCC_A1, type code %A, sha256 2f59cdf668abb9e9…

59: PHASE FCC_A1 %A 2 1 1 !
60: CONST FCC_A1 : MN : VA : !

MnO-10Kje.tdb: FCC_A1, type code %A, sha256 bd1f5b2a6c1bd76e…

52: PHASE FCC_A1 %A 2 1 1 !
53: CONST FCC_A1 : MN : VA : !

Example references (2 of 2; assessments first):

doi:10.1007/s11669-003-0004-6 A. Nicholas Grundy, Bengt Hallstedt, Ludwig J. Gauckler, Assessment of the Mn-O system, JPE 24, 21-39 (2003).
assessment that models this phase; reports values for this phase
doi:10.1007/s11669-009-9643-6 Lina Kjellqvist, Malin Selleby, Thermodynamic Assessment of the Fe-Mn-O System, J. Phase Equilib. Diffus. 31, 113-134 (2010).
assessment that models this phase

GAS (Mn–O)

Id: phase:mn-o:gas; status assigned
Structure: gas; type st:gas; gas; confidence high
Stability: stable in 2 of 2 calculated diagram(s): 1158.26–2500 K, x(O) 0–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:mn-o:gas
tdb: tdb:MnO-03Gru-LB.tdb:GAS, tdb:MnO-10Kje.tdb:GAS

TDB models of GAS (2): PHASE and CONSTITUENT statements as written

MnO-03Gru-LB.tdb: GAS, type code %, sha256 2f59cdf668abb9e9…

111: PHASE GAS:G % 1 1 !
112: CONST GAS:G : MN MNO MNO2 O O2 O3 : !

MnO-10Kje.tdb: GAS, type code %, sha256 bd1f5b2a6c1bd76e…

110: PHASE GAS:G % 1 1 !
111: CONST GAS:G : MN MNO MNO2 O O2 O3 : !

Example references (2 of 2; assessments first):

doi:10.1007/s11669-003-0004-6 A. Nicholas Grundy, Bengt Hallstedt, Ludwig J. Gauckler, Assessment of the Mn-O system, JPE 24, 21-39 (2003).
assessment that models this phase
doi:10.1007/s11669-009-9643-6 Lina Kjellqvist, Malin Selleby, Thermodynamic Assessment of the Fe-Mn-O System, J. Phase Equilib. Diffus. 31, 113-134 (2010).
assessment that models this phase

SPINEL_H11 (Mn–O)

Id: phase:mn-o:h11-spinel; status assigned
Structure: Al2MgO4 · H1_1 · cF56 · Fd-3m (227); type st:h1-1-al2mgo4-cf56; tier C: assessor-stated (Hallstedt 2025 crystallographic table); confidence assessor-stated
Structure source: B. Hallstedt, The SGTE collection of binary datasets, Calphad 89 (2025) 102833, supplementary crystallographic table (mmc2) doi:10.1016/j.calphad.2025.102833
Caveat: not certain from the name or DFT alone (unrecognised_name_tokens:SPINEL); structure as stated in the SGTE crystallographic table for this phase name and system
Stability: stable in 1 of 1 calculated diagram(s): 1408.45–1878.72 K, x(O) 0.57123–0.5716
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:mn-o:h11-spinel
tdb: tdb:MnO-10Kje.tdb:SPINEL_H11

TDB models of SPINEL_H11 (1): PHASE and CONSTITUENT statements as written

MnO-10Kje.tdb: SPINEL_H11, type code %A, sha256 bd1f5b2a6c1bd76e…

104: PHASE SPINEL_H11:I %A 4 1 2 2 4 !
105: CONST SPINEL_H11:I : MN+2 : MN+2 MN+3 MN+4 VA : MN+2 VA% : O-2 : !

Example references (1 of 1; assessments first):

doi:10.1007/s11669-009-9643-6 Lina Kjellqvist, Malin Selleby, Thermodynamic Assessment of the Fe-Mn-O System, J. Phase Equilib. Diffus. 31, 113-134 (2010).
assessment that models this phase

HCP_A3 (Mn–O)

Id: phase:mn-o:hcp-a3; status assigned
Structure: Mg · A3 · hP2 · P6_3/mmc (194); type st:a3-mg-hp2; tier A: standard phase name; confidence high
Stoichiometry: Mn 1.0000
Stability: not stable in 2 calculated diagram(s)
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:mn-o:hcp-a3
tdb: tdb:MnO-03Gru-LB.tdb:HCP_A3, tdb:MnO-10Kje.tdb:HCP_A3

TDB models of HCP_A3 (2): PHASE and CONSTITUENT statements as written

MnO-03Gru-LB.tdb: HCP_A3, type code %A, sha256 2f59cdf668abb9e9…

69: PHASE HCP_A3 %A 2 1 0.5 !
70: CONST HCP_A3 : MN : VA : !

MnO-10Kje.tdb: HCP_A3, type code %A, sha256 bd1f5b2a6c1bd76e…

62: PHASE HCP_A3 %A 2 1 0.5 !
63: CONST HCP_A3 : MN : VA : !

Example references (2 of 2; assessments first):

doi:10.1007/s11669-003-0004-6 A. Nicholas Grundy, Bengt Hallstedt, Ludwig J. Gauckler, Assessment of the Mn-O system, JPE 24, 21-39 (2003).
assessment that models this phase
doi:10.1007/s11669-009-9643-6 Lina Kjellqvist, Malin Selleby, Thermodynamic Assessment of the Fe-Mn-O System, J. Phase Equilib. Diffus. 31, 113-134 (2010).
assessment that models this phase

ION (Mn–O)

Id: phase:mn-o:ion; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 2 of 2 calculated diagram(s): 1518.46–2500 K, x(O) 0–0.55266
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:mn-o:ion
tdb: tdb:MnO-03Gru-LB.tdb:ION, tdb:MnO-10Kje.tdb:ION

TDB models of ION (2): PHASE and CONSTITUENT statements as written

MnO-03Gru-LB.tdb: ION, type code %, sha256 2f59cdf668abb9e9…

54: PHASE ION:Y % 2 1 1 !
55: CONST ION:Y : MN+2 MN+3 : O-2 VA : !

MnO-10Kje.tdb: ION, type code %, sha256 bd1f5b2a6c1bd76e…

47: PHASE ION:Y % 2 1 1 !
48: CONST ION:Y : MN+2 : O-2 VA MNO1.5 : !

Example references (2 of 2; assessments first):

doi:10.1007/s11669-003-0004-6 A. Nicholas Grundy, Bengt Hallstedt, Ludwig J. Gauckler, Assessment of the Mn-O system, JPE 24, 21-39 (2003).
assessment that models this phase
doi:10.1007/s11669-009-9643-6 Lina Kjellqvist, Malin Selleby, Thermodynamic Assessment of the Fe-Mn-O System, J. Phase Equilib. Diffus. 31, 113-134 (2010).
assessment that models this phase

LIQUID (Mn–O)

Id: phase:mn-o:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stoichiometry: Mn 1.0000
Stability: stable in 1 of 2 calculated diagram(s): 1503.51–1503.51 K, x(O) 0–0
Literature: 35 values (35 accepted) from 1 papers
Interactive: phase registry entry

Names (8): corpus: corpus:phase:mn-o:liquid
paper: paper:10.1007/s11669-003-0004-6:L1, paper:10.1007/s11669-003-0004-6:L2, paper:10.1007/s11669-003-0004-6:Liq, paper:10.1007/s11669-003-0004-6:Liquid, paper:10.1007/s11669-003-0004-6:liquid
tdb: tdb:MnO-03Gru-LB.tdb:LIQUID, tdb:MnO-10Kje.tdb:LIQUID

TDB models of LIQUID (2): PHASE and CONSTITUENT statements as written

MnO-03Gru-LB.tdb: LIQUID, type code %, sha256 2f59cdf668abb9e9…

51: PHASE LIQUID:L % 1 1 !
52: CONST LIQUID:L : MN : !

MnO-10Kje.tdb: LIQUID, type code %, sha256 bd1f5b2a6c1bd76e…

44: PHASE LIQUID:L % 1 1 !
45: CONST LIQUID:L : MN : !

Example references (10 of 11; assessments first):

doi:10.1007/s11669-003-0004-6 A. Nicholas Grundy, Bengt Hallstedt, Ludwig J. Gauckler, Assessment of the Mn-O system, JPE 24, 21-39 (2003).
assessment that models this phase; reports values for this phase
doi:10.1007/s11669-009-9643-6 Lina Kjellqvist, Malin Selleby, Thermodynamic Assessment of the Fe-Mn-O System, J. Phase Equilib. Diffus. 31, 113-134 (2010).
assessment that models this phase
doi:10.1002/srin.196402318 Hermann Schenck, Martin G. Frohberg, Reginald Nünninghoff, Das System MnO(–FeO)–MgO(–CaO) und seine Verteilungsgleichgewichte mit flüssigem Mangan und Eisen‐Mangan‐Legierungen, Steel Research Intl 35, 269-277 (1964).
cited as the source of values for this phase
doi:10.1002/srin.198405356 Eberhard Schürmann, Norbert Bannenberg, Metall-Schlackengleichgewichte im System Eisen-Mangan-Schwefel-Sauerstoff als Grundlage der Mangandesoxidation von Stahlschmelzen bei gleichzeitiger Anwesenheit von Schwefel, Archiv für das Eisenhüttenwesen 55, 349-358 (1984).
cited as the source of values for this phase
doi:10.1149/1.2426584 A. Z. Hed, D. S. Tannhauser, Contribution to the Mn-O Phase Diagram at High Temperature, J. Electrochem. Soc. 114, 314 (1967).
cited as the source of values for this phase
doi:10.1002/srin.196904332 Norbert G. Schmahl, Detlev F. K. Hennings, Das Zustandsdiagramm Mn3 O4 -MnO und die in ihm auftretenden Zersetzungsdrücke, Archiv für das Eisenhüttenwesen 40, 395-399 (1969).
cited as the source of values for this phase
doi:10.2475/ajs.258.1.66 W. C. Hahn, A. Muan, Studies in the system Mn-O--The Mn 2 O 3 -Mn 3 O 4 and Mn 3 O 4 -MnO equilibria, American Journal of Science 258, 66-78 (1960).
cited as the source of values for this phase
doi:10.1002/srin.195702172 Hermann Schenck, Norbert G. Schmahl, A. K. Biswas, Untersuchungen über das Zustandsschaubild Eisen(II)-oxyd-Mangan(II)-oxyd und seine Beziehung zur Desoxydation von reinem Eisen mit Mangan, Archiv für das Eisenhüttenwesen 28, 517-521 (1957).
cited as the source of values for this phase
doi:10.1002/srin.196103182 Wilhelm Anton Fischer, Hans Joachim Fleischer, Die Manganverteilung zwischen Eisenschmelzen und Eisen(II)‐oxydschlacken im MnO‐Tiegel bei 1520 bis 1770°C, Steel Research Intl 32, 1-10 (1961).
cited as the source of values for this phase
doi:10.1016/0364-5916(91)90030-n A.T. Dinsdale, SGTE data for pure elements, Calphad 15, 317-425 (1991).
cited as the source of values for this phase

MN2O3_D53 (Mn–O)

Id: phase:mn-o:mn2o3-d53; status assigned
Structure: Mn2O3 · D5_3 · cI80 · Ia-3 (206); type st:d5-3-mn2o3-ci80; tier A: standard phase name; confidence high
Stability: stable in 2 of 2 calculated diagram(s): 300–1237.26 K, x(O) 0.6–0.6
Literature: 55 values (45 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:mn-o:mn2o3-d53
paper: paper:10.1007/s11669-003-0004-6:Mn2O3
tdb: tdb:MnO-03Gru-LB.tdb:MN2O3_D53, tdb:MnO-10Kje.tdb:MN2O3_D53

TDB models of MN2O3_D53 (2): PHASE and CONSTITUENT statements as written

MnO-03Gru-LB.tdb: MN2O3_D53, type code %, sha256 2f59cdf668abb9e9…

100: PHASE MN2O3_D53:I % 2 2 3 !
101: CONST MN2O3_D53:I : MN+3 : O-2 : !

MnO-10Kje.tdb: MN2O3_D53, type code %, sha256 bd1f5b2a6c1bd76e…

92: PHASE MN2O3_D53:I % 2 2 3 !
93: CONST MN2O3_D53:I : MN+3 : O-2 : !

Example references (10 of 16; assessments first):

doi:10.1007/s11669-003-0004-6 A. Nicholas Grundy, Bengt Hallstedt, Ludwig J. Gauckler, Assessment of the Mn-O system, JPE 24, 21-39 (2003).
assessment that models this phase; reports values for this phase
doi:10.1007/s11669-009-9643-6 Lina Kjellqvist, Malin Selleby, Thermodynamic Assessment of the Fe-Mn-O System, J. Phase Equilib. Diffus. 31, 113-134 (2010).
assessment that models this phase
doi:10.1002/zaac.19080570105 R. J. Meyer, Kurt Rötgers, Die Dissoziationstemperaturen der Manganoxyde MnO2 und Mn2O3 in Luft und Sauerstoff, Z. Anorg. Chem. 57, 104-112 (1908).
cited as the source of values for this phase
doi:10.1149/1.2423551 Earl M. Otto, Equilibrium Pressures of Oxygen over MnO[sub 2]-Mn[sub 2]O[sub 3] at Various Temperatures, J. Electrochem. Soc. 112, 367 (1965).
cited as the source of values for this phase
doi:10.1021/cr60256a003 T. A. Zordan, Loren G. Hepler, Thermochemistry and oxidation potentials of manganese and its compounds, Chem. Rev. 68, 737-745 (1968).
cited as the source of values for this phase
doi:10.1179/cmq.1967.6.1.71 K. Hochgeschwender, T .R. Ingraham, Use of Thermal Conductivity Gas Analysis for Thermodynamic Measurements on the Dissociation of CuO, Mn2O3and MnO2, Canadian Metallurgical Quarterly 6, 71-84 (1967).
cited as the source of values for this phase
doi:10.6028/jres.041.046 Howard F. McMurdie, Esther Golovato, Study of the modifications of manganese dioxide, J. RES. NATL. BUR. STAN. 41, 589 (1948).
cited as the source of values for this phase
doi:10.1002/srin.194001311 Hermann Ulich, Hans Siemonsen, Beitrag zur Metallurgie des Mangans durch thermochemische Messungen und Gleichgewichtsberechnungen, Archiv für das Eisenhüttenwesen 14, 27-34 (1940).
cited as the source of values for this phase
doi:10.1002/srin.196304016 Norbert G. Schmahl, Fayek Shenouda, Die thermische Zersetzung des Mangan(III)‐oxyds (Mn2O3), Steel Research Intl 34, 511-518 (1963).
cited as the source of values for this phase
doi:10.1016/0021-9614(85)90069-2 Richard A. Robie, Bruce S. Hemingway, Low-temperature molar heat capacities and entropies of MnO2 (pyrolusite), Mn3O4 (hausmanite), and Mn2O3 (bixbyite), The Journal of Chemical Thermodynamics 17, 165-181 (1985).
cited as the source of values for this phase

MN3O4_A (Mn–O)

Id: phase:mn-o:mn3o4-a; status needs_review
No structure assigned. Why: name_has_descriptive_tokens:A; no_structure_token
Candidate (dft_mp): I4_1/amd (141) — on-hull MP Mn3O4 at x(O)=0.5714
Candidate (dft_oqmd): I41/amd (141) — on-hull OQMD Mn3 O4 at x(O)=0.5714
Candidate (tdb_comment): Mn3O4 · tI28 · I4_1/amd, tetragonally distorted (Jahn-Teller — MnO-10Kje.tdb: 'Prototype Mn3O4 (tI28, I4_1/amd, tetragonally distorted (Jahn-Teller) spinel)'
Stability: stable in 1 of 1 calculated diagram(s): 300–1505 K, x(O) 0.57128–0.57161
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:mn-o:mn3o4-a
tdb: tdb:MnO-10Kje.tdb:MN3O4_A

TDB models of MN3O4_A (1): PHASE and CONSTITUENT statements as written

MnO-10Kje.tdb: MN3O4_A, type code %A, sha256 bd1f5b2a6c1bd76e…

86: PHASE MN3O4_A:I %A 4 1 2 2 4 !
87: CONST MN3O4_A:I : MN+2 MN+3 : MN+2 MN+3 VA : MN+2 VA : O-2 : !

Example references (1 of 1; assessments first):

doi:10.1007/s11669-009-9643-6 Lina Kjellqvist, Malin Selleby, Thermodynamic Assessment of the Fe-Mn-O System, J. Phase Equilib. Diffus. 31, 113-134 (2010).
assessment that models this phase

MN3O4_ALPHA (Mn–O)

Id: phase:mn-o:mn3o4-alpha; status assigned
Structure: Mn3O4 · tI28 · I4_1/amd (141); type st:mn3o4-ti28; tier C: assessor-stated (Hallstedt 2025 crystallographic table); confidence assessor-stated
Structure source: B. Hallstedt, The SGTE collection of binary datasets, Calphad 89 (2025) 102833, supplementary crystallographic table (mmc2) doi:10.1016/j.calphad.2025.102833
Caveat: not certain from the name or DFT alone (no_structure_token, off_stoichiometric_model); structure as stated in the SGTE crystallographic table for this phase name and system
Stability: stable in 1 of 1 calculated diagram(s): 300–1442.97 K, x(O) 0.57143–0.57143
Literature: 45 values (45 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:mn-o:mn3o4-alpha
paper: paper:10.1007/s11669-003-0004-6:α-Mn3O4
tdb: tdb:MnO-03Gru-LB.tdb:MN3O4_ALPHA

TDB models of MN3O4_ALPHA (1): PHASE and CONSTITUENT statements as written

MnO-03Gru-LB.tdb: MN3O4_ALPHA, type code %, sha256 2f59cdf668abb9e9…

90: PHASE MN3O4_ALPHA:I % 3 1 2 4 !
91: CONST MN3O4_ALPHA:I : MN+2 : MN+3 : O-2 : !

Example references (10 of 14; assessments first):

doi:10.1007/s11669-003-0004-6 A. Nicholas Grundy, Bengt Hallstedt, Ludwig J. Gauckler, Assessment of the Mn-O system, JPE 24, 21-39 (2003).
assessment that models this phase; reports values for this phase
doi:10.1149/1.2411434 G. G. Charette, S. N. Flengas, Thermodynamic Properties of the Oxides of Fe, Ni, Pb, Cu, and Mn, by EMF Measurements, J. Electrochem. Soc. 115, 796 (1968).
cited as the source of values for this phase
doi:10.1002/bbpc.19850890815 M. Keller, R. Dieckmann, Defect Structure and Transport Properties of Manganese Oxides: (I) The Nonstoichiometry of Manganosite (Mn1‐ΔO), Ber Bunsenges Phys Chem 89, 883-893 (1985).
cited as the source of values for this phase
doi:10.1007/bf01046534 H.S. O’Neill and M.I. Pownceby: “Thermodynamic Data From the Redox Reactions at High Temperatures. I. An Experimental and Theoretical Assessment of the Electrochemical Method Using Stabilized Zirconia Electrolytes, With Revised Values for the Fe-⬘FeO⬘, Co-CoO, Ni-NiO and Cu-Cu2O Oxygen Buffers and New Data for the W-WO2 Buffer,” Contrib. Mineral. Petrol., 1993, 114, pp. 296-314.
cited as the source of values for this phase
doi:10.6028/jres.041.046 Howard F. McMurdie, Esther Golovato, Study of the modifications of manganese dioxide, J. RES. NATL. BUR. STAN. 41, 589 (1948).
cited as the source of values for this phase
doi:10.1002/srin.196304016 Norbert G. Schmahl, Fayek Shenouda, Die thermische Zersetzung des Mangan(III)‐oxyds (Mn2O3), Steel Research Intl 34, 511-518 (1963).
cited as the source of values for this phase
doi:10.1002/zaac.19080570105 R. J. Meyer, Kurt Rötgers, Die Dissoziationstemperaturen der Manganoxyde MnO2 und Mn2O3 in Luft und Sauerstoff, Z. Anorg. Chem. 57, 104-112 (1908).
cited as the source of values for this phase
doi:10.1002/zaac.19663460310 A. Schmier, G. Sterr, Beitrag zur Kenntnis der Hausmannitphase, Zeitschrift anorg allge chemie 346, 181-187 (1966).
cited as the source of values for this phase
doi:10.1016/0022-3697(62)90530-9 K.S Irani, A.P.B Sinha, A.B Biswas, Effect of temperature on the structure of manganites, Journal of Physics and Chemistry of Solids 23, 711-727 (1962).
cited as the source of values for this phase
doi:10.1016/0022-4596(81)90064-5 R. Metselaar, R.E.J. Van Tol, P. Piercy, The electrical conductivity and thermoelectric power of Mn3O4 at high temperatures, Journal of Solid State Chemistry 38, 335-341 (1981).
cited as the source of values for this phase

MN3O4_H11 (Mn–O)

Id: phase:mn-o:mn3o4-h11; status assigned
Structure: Al2MgO4 · H1_1 · cF56 · Fd-3m (227); type st:h1-1-al2mgo4-cf56; tier A: standard phase name; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 1442.97–1882.41 K, x(O) 0.57143–0.57143
Literature: 38 values (38 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:mn-o:mn3o4-h11
paper: paper:10.1007/s11669-003-0004-6:β-Mn3O4
tdb: tdb:MnO-03Gru-LB.tdb:MN3O4_H11

TDB models of MN3O4_H11 (1): PHASE and CONSTITUENT statements as written

MnO-03Gru-LB.tdb: MN3O4_H11, type code %, sha256 2f59cdf668abb9e9…

95: PHASE MN3O4_H11:I % 3 1 2 4 !
96: CONST MN3O4_H11:I : MN+2 : MN+3 : O-2 : !

Example references (10 of 11; assessments first):

doi:10.1007/s11669-003-0004-6 A. Nicholas Grundy, Bengt Hallstedt, Ludwig J. Gauckler, Assessment of the Mn-O system, JPE 24, 21-39 (2003).
assessment that models this phase; reports values for this phase
doi:10.1002/srin.196904332 Norbert G. Schmahl, Detlev F. K. Hennings, Das Zustandsdiagramm Mn3 O4 -MnO und die in ihm auftretenden Zersetzungsdrücke, Archiv für das Eisenhüttenwesen 40, 395-399 (1969).
cited as the source of values for this phase
doi:10.1149/1.2426584 A. Z. Hed, D. S. Tannhauser, Contribution to the Mn-O Phase Diagram at High Temperature, J. Electrochem. Soc. 114, 314 (1967).
cited as the source of values for this phase
doi:10.2475/ajs.258.1.66 W. C. Hahn, A. Muan, Studies in the system Mn-O--The Mn 2 O 3 -Mn 3 O 4 and Mn 3 O 4 -MnO equilibria, American Journal of Science 258, 66-78 (1960).
cited as the source of values for this phase
doi:10.1002/bbpc.19850890815 M. Keller, R. Dieckmann, Defect Structure and Transport Properties of Manganese Oxides: (I) The Nonstoichiometry of Manganosite (Mn1‐ΔO), Ber Bunsenges Phys Chem 89, 883-893 (1985).
cited as the source of values for this phase
doi:10.1002/zaac.19663460310 A. Schmier, G. Sterr, Beitrag zur Kenntnis der Hausmannitphase, Zeitschrift anorg allge chemie 346, 181-187 (1966).
cited as the source of values for this phase
doi:10.1016/0022-3697(62)90530-9 K.S Irani, A.P.B Sinha, A.B Biswas, Effect of temperature on the structure of manganites, Journal of Physics and Chemistry of Solids 23, 711-727 (1962).
cited as the source of values for this phase
doi:10.1016/0022-4596(81)90064-5 R. Metselaar, R.E.J. Van Tol, P. Piercy, The electrical conductivity and thermoelectric power of Mn3O4 at high temperatures, Journal of Solid State Chemistry 38, 335-341 (1981).
cited as the source of values for this phase
doi:10.1016/s0020-1693(00)93169-4 F.C.M. Driessens, Place and valence of the cations in Mn3O4 and some related manganates, Inorganica Chimica Acta 1, 193-201 (1967).
cited as the source of values for this phase
doi:10.1021/ja01260a007 J. C. Southard, G. E. Moore, High-temperature Heat Content of Mn3O4, MnSiO3 and Mn3C1, J. Am. Chem. Soc. 64, 1769-1770 (1942).
cited as the source of values for this phase

MNO2_C4 (Mn–O)

Id: phase:mn-o:mno2-c4; status assigned
Structure: TiO2 · C4 · tP6 · P4_2/mnm (136); type st:c4-tio2-tp6; tier A: standard phase name; confidence high
Stability: stable in 2 of 2 calculated diagram(s): 300–485 K, x(O) 0.66667–0.66667
Literature: 50 values (40 accepted) from 1 papers
Interactive: phase registry entry

Names (5): corpus: corpus:phase:mn-o:mno2-c4
paper: paper:10.1007/s11669-003-0004-6:MnO2, paper:10.1007/s11669-003-0004-6:α-MnO2
tdb: tdb:MnO-03Gru-LB.tdb:MNO2_C4, tdb:MnO-10Kje.tdb:MNO2_C4

TDB models of MNO2_C4 (2): PHASE and CONSTITUENT statements as written

MnO-03Gru-LB.tdb: MNO2_C4, type code %, sha256 2f59cdf668abb9e9…

105: PHASE MNO2_C4:I % 2 1 2 !
106: CONST MNO2_C4:I : MN+4 : O-2 : !

MnO-10Kje.tdb: MNO2_C4, type code %, sha256 bd1f5b2a6c1bd76e…

98: PHASE MNO2_C4:I % 2 1 2 !
99: CONST MNO2_C4:I : MN+4 : O-2 : !

Example references (10 of 15; assessments first):

doi:10.1007/s11669-003-0004-6 A. Nicholas Grundy, Bengt Hallstedt, Ludwig J. Gauckler, Assessment of the Mn-O system, JPE 24, 21-39 (2003).
assessment that models this phase; reports values for this phase
doi:10.1007/s11669-009-9643-6 Lina Kjellqvist, Malin Selleby, Thermodynamic Assessment of the Fe-Mn-O System, J. Phase Equilib. Diffus. 31, 113-134 (2010).
assessment that models this phase
doi:10.1002/zaac.19080570105 R. J. Meyer, Kurt Rötgers, Die Dissoziationstemperaturen der Manganoxyde MnO2 und Mn2O3 in Luft und Sauerstoff, Z. Anorg. Chem. 57, 104-112 (1908).
cited as the source of values for this phase
doi:10.1149/1.2423551 Earl M. Otto, Equilibrium Pressures of Oxygen over MnO[sub 2]-Mn[sub 2]O[sub 3] at Various Temperatures, J. Electrochem. Soc. 112, 367 (1965).
cited as the source of values for this phase
doi:10.1021/cr60256a003 T. A. Zordan, Loren G. Hepler, Thermochemistry and oxidation potentials of manganese and its compounds, Chem. Rev. 68, 737-745 (1968).
cited as the source of values for this phase
doi:10.1021/ja01245a015 K. K. Kelley, G. E. Moore, Specific Heats at Low Temperatures of Manganese Carbide and Manganese Dioxide1, J. Am. Chem. Soc. 65, 782-785 (1943).
cited as the source of values for this phase
doi:10.1179/cmq.1967.6.1.71 K. Hochgeschwender, T .R. Ingraham, Use of Thermal Conductivity Gas Analysis for Thermodynamic Measurements on the Dissociation of CuO, Mn2O3and MnO2, Canadian Metallurgical Quarterly 6, 71-84 (1967).
cited as the source of values for this phase
doi:10.1002/srin.194001311 Hermann Ulich, Hans Siemonsen, Beitrag zur Metallurgie des Mangans durch thermochemische Messungen und Gleichgewichtsberechnungen, Archiv für das Eisenhüttenwesen 14, 27-34 (1940).
cited as the source of values for this phase
doi:10.1016/0021-9614(85)90069-2 Richard A. Robie, Bruce S. Hemingway, Low-temperature molar heat capacities and entropies of MnO2 (pyrolusite), Mn3O4 (hausmanite), and Mn2O3 (bixbyite), The Journal of Chemical Thermodynamics 17, 165-181 (1985).
cited as the source of values for this phase
doi:10.1021/cr60161a001 Leo. Brewer, Thermodynamic Properties of the Oxides and their Vaporization Processes., Chem. Rev. 52, 1-75 (1953).
cited as the source of values for this phase

O2GAS (Mn–O)

Id: phase:mn-o:o2gas; status assigned
Structure: gas; type st:gas; gas; confidence high
Stability: stable in 2 of 2 calculated diagram(s): 300–485 K, x(O) 1–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:mn-o:o2gas
tdb: tdb:MnO-03Gru-LB.tdb:O2GAS, tdb:MnO-10Kje.tdb:O2GAS

TDB models of O2GAS (2): PHASE and CONSTITUENT statements as written

MnO-03Gru-LB.tdb: O2GAS, type code %, sha256 2f59cdf668abb9e9…

108: PHASE O2GAS % 1 1 !
109: CONST O2GAS : O2 :!

MnO-10Kje.tdb: O2GAS, type code %, sha256 bd1f5b2a6c1bd76e…

107: PHASE O2GAS % 1 1 !
108: CONST O2GAS : O2 :!

Example references (2 of 2; assessments first):

doi:10.1007/s11669-003-0004-6 A. Nicholas Grundy, Bengt Hallstedt, Ludwig J. Gauckler, Assessment of the Mn-O system, JPE 24, 21-39 (2003).
assessment that models this phase
doi:10.1007/s11669-009-9643-6 Lina Kjellqvist, Malin Selleby, Thermodynamic Assessment of the Fe-Mn-O System, J. Phase Equilib. Diffus. 31, 113-134 (2010).
assessment that models this phase

Please cite

R. Arróyave, J. Saal, D. Shin, ORCHID-Registry: phase registry of binary systems (version 2026.10; Version 1, machine-extracted), Zenodo (2026). doi:10.5281/zenodo.23735970
R. Arróyave, J. Saal, D. Shin, ORCHID data: umbrella record of the ORCHID datasets (version 2026.10; Version 1, machine-extracted), Zenodo (2026). doi:10.5281/zenodo.23736065

Also cite B. Hallstedt, The SGTE collection of binary datasets, Calphad 89 (2025) 102833, https://doi.org/10.1016/j.calphad.2025.102833 (CC BY 4.0), and the original assessment named in each file; A. Jain et al., The Materials Project: A materials genome approach to accelerating materials innovation, APL Materials 1 (2013) 011002, https://doi.org/10.1063/1.4812323 (CC BY 4.0); J. E. Saal et al., JOM 65 (2013) 1501, https://doi.org/10.1007/s11837-013-0755-4 and S. Kirklin et al., npj Comput. Mater. 1 (2015) 15010, https://doi.org/10.1038/npjcompumats.2015.10 (CC BY 4.0); the original source of every value you use (paper_citation / paper_doi, and cited_dois for values the paper cites from earlier work). Version 1, machine-extracted: values were read by language-model readers constrained to quote their source and checked automatically, and the release was then audited on the printed pages by adversarial audits, an independent second review of fit-facing records and a preliminary human review of a frozen sample. Flags such as accepted and ESPEI-ready record screening results, not certification; known issues are listed in the release notes.

@misc{orchid_phase_registry_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID-Registry: phase registry of binary systems}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23735970},
  url       = {https://doi.org/10.5281/zenodo.23735970},
  note      = {Version 1, machine-extracted}
}

@misc{orchid_data_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID data: umbrella record of the ORCHID datasets}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23736065},
  url       = {https://doi.org/10.5281/zenodo.23736065},
  note      = {Version 1, machine-extracted}
}