Novel K/Mn phosphate hydrates, K 2 Mn 3 (H 2 O) 2 [P 2 O 7 ] 2 and KMn(H 2 O) 2 [Al 2 (PO 4 ) 3 ]: hydrothermal synthesis and crystal chemistry

• Published in: Acta crystallographica. Section C, Structural chemistry Vol. 76; no. Pt 3; pp. 302 - 310
• Main Authors: Kiriukhina, Galina V, Yakubovich, Olga V, Shvanskaya, Larisa V, Kochetkova, Ekaterina M, Dimitrova, Olga V, Volkov, Anatoliy S, Simonov, Sergey V
• Format: Journal Article
• Language: English
• Published: England 01-03-2020
• Subjects: morphotropic series; paramagnet; hydrothermal synthesis; diphosphate; X-ray diffraction; crystal structure; aluminophosphate; feldspar; open framework
• ISSN: 2053-2296; 2053-2296
• DOI: 10.1107/S2053229620002466

Two novel K/Mn phosphate hydrates, namely, dipotassium trimanganese dipyrophosphate dihydrate, K
Mn
(H
O)
[P
O
]
, (I), and potassium manganese dialuminium triphosphate dihydrate, KMn(H
O)
[Al
(PO
)
], (II), were obtained in the form of single crystals during a single hydrothermal synthesis experiment. Their crystal structures were studied by X-ray diffraction. Both new compounds are members of the morphotropic series of phosphates with the following formulae: A
M
(H
O)
[P
O
]
, where A = K, NH
, Rb or Na and M = Mn, Fe, Co or Ni, and AM
(H
O)
[M
(PO
)
], where A = Cs, Rb, K, NH
or (H
O); M
= Mn, Fe, Co or Ni; and M
= Al, Ga or Fe. A detailed crystal chemical analysis revealed correlations between the unit-cell parameters of the members of the series, their structural features and the sizes of the cations. It has been shown that a mixed type anionic framework is formed in (II) by aluminophosphate [(AlO
)
(PO
)
]
layers, with a cationic topology similar to the Si/Al-topology of the crystal structures of feldspars. A study of the magnetic susceptibility of (II) demonstrates a paramagnetic behaviour of the compound.