Crystal chemistry of ammonium phases from the burned dumps of the Chelyabinsk Coal Basin

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Marco E. Ciriotti
Messaggi: 25818
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
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Crystal chemistry of ammonium phases from the burned dumps of the Chelyabinsk Coal Basin

Messaggio da Marco E. Ciriotti » mer 14 ago, 2019 18:42

Referenza:
▪ Zolotarev, A.A., Jr., Zhitova, E.S., Krzhizhanovskaya, M.G., Rassomakhin, M.A., Shilovskikh, V.V., Krivovichev, S.V. (2019): Crystal Chemistry and High-Temperature Behaviour of Ammonium Phases NH4MgCl3·6H2O and (NH4)2Fe3+Cl5·H2O from the Burned Dumps of the Chelyabinsk Coal Basin. Minerals, 9, 486; https://doi.org/10.3390/min908048

Abstract:
The technogenic mineral phases NH4MgCl3·6H2O and (NH4)2Fe3+Cl5·H2O from the burned dumps of the Chelyabinsk coal basin have been investigated by single-crystal X-ray diffraction, scanning electron microscopy and high-temperature powder X-ray diffraction. The NH4MgCl3·6H2O phase is monoclinic, space group C2/c, unit cell parameters a = 9.3091(9), b = 9.5353(7), c = 13.2941(12) Å, β = 90.089(8)° and V = 1180.05(18) Å3. The crystal structure of NH4MgCl3·6H2O was refined to R1 = 0.078 (wR2 = 0.185) on the basis of 1678 unique reflections. The (NH4)2Fe3+Cl5·H2O phase is orthorhombic, space group Pnma, unit cell parameters a = 13.725(2), b = 9.9365(16), c = 7.0370(11) Å and V = 959.7(3) Å3. The crystal structure of (NH4)2Fe3+Cl5·H2O was refined to R1 = 0.023 (wR2 = 0.066) on the basis of 2256 unique reflections. NH4MgCl3·6H2O is stable up to 90 °C and then transforms to the less hydrated phase isotypic to β-Rb(MnCl3)(H2O)2 (i.e., NH4MgCl3·2H2O), the latter phase being stable up to 150 °C. (NH4)2Fe3+Cl5·H2O is stable up to 120 °C and then transforms to an X-ray amorphous phase. Hydrogen bonds provide an important linkage between the main structural units and play the key role in determining structural stability and physical properties of the studied phases. The mineral phases NH4MgCl3·6H2O and (NH4)2Fe3+Cl5·H2O are isostructural with natural minerals novograblenovite and kremersite, respectively.
Marco E. Ciriotti

«Things are interesting only in so far as they relate themselves to other things»

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Marco E. Ciriotti
Messaggi: 25818
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
Contatta:

Re: Crystal chemistry of ammonium phases from the burned dumps of the Chelyabinsk Coal Basin

Messaggio da Marco E. Ciriotti » mer 14 ago, 2019 21:25

Le valide specie minerali aventi (NH4) come elemento essenziale sono 83.
Molte di esse sono state identificate, approvate e descritte in tempi recenti.

Bazhenovite, godovikovite, dmisteinbergite, svyatoslavite, rorisite, efremovite, srebrodolskite e fluorellestadite sono specie, regolarmente approvate, aventi come località-tipo le discariche ardenti di Chelyabinsk.

Le due fasi tecnogeniche descritte nel lavoro in oggetto, sono state precedentemente o successivamente trovate in ambienti naturali (vulcani) e regolarmente approvate con il nome di kremersite, (NH4)2[Fe3+Cl5(H2O)], e novograblenovite, (NH4)MgCl3·6H2O.
Marco E. Ciriotti

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