SIMONKOLLEITE, Zn5 (OH)8 Cl2 (H2O), A DECORATED INTERRUPTED-SHEET STRUCTURE OF THE FORM [M 2]4

Abstract

The crystal structure of simonkolleite, Zn 5 (OH) 8 Cl 2 (H 2 O), rhombohedral, space group R3m, a 6.3412(3), c 23.646(1) Å, V 823.4(1) Å 3 , Z = 3, has been refined to an R index of 1.6% based on 284 observed (5) reflections measured with MoK␣ Xradiation. There are two distinct Zn sites fully occupied by Zn: Zn(1) is octahedrally coordinated by six (OH) groups, <Zn(1)-OH> = 2.127 Å, and Zn(2) is tetrahedrally coordinated by three (OH) groups and one Cl atom, <Zn(2)-OH,Cl> = 2.041 Å. The (Zn 6) octahedra (: O, OH, Cl) form an edge-sharing dioctahedral sheet similar to that observed in dioctahedral micas. On each side of the vacant octahedron, a (Zn 4) tetrahedron is attached to three anions of the sheet and points away from the sheet. The decorated sheet can be written as [M 3 (T 4) 2 2 ], where M = [6] Zn, T = [4] Zn and = OH, Cl. Intercalated between adjacent sheets are interstitial (H 2 O) groups. The sheets are held together by hydrogen bonding from (OH) groups of one sheet to Cl anions of adjacent sheets, and to interstitial (H 2 O) groups. Simonkolleite can be considered as a decorated sheet structure of the form [ [6] M 2 ] 4 with an interrupted sheet, and is related to the structures of cianciulliite, gordaite, namuwite, bechererite, chalcophyllite, ramsbeckite, chalcophanite and claringbullite.

Simonkolleite-graphene foam composites and their superior electrochemical performance

“…They also crystallize hexagonally with a perfect cleavage parallel to the (001) direction [12]. Similar to metal oxides, simonkolleites contain electrochemically active sites necessary for efficient charge storage.…”

Hydrothermal synthesis of simonkolleite microplatelets on nickel foam-graphene for electrochemical supercapacitors

“…Most reports on simonkolleite deal with its bulk properties, with a net focus on understanding the surface atmospheric corrosion products on Zn plates [26,27]. Simonkolleite forms hexagonal microplatelet crystals with a perfect cleavage parallel to the (001) direction [28]. It is a soft compound with a Mohs hardness of 1.5 and a specific gravity of 3.2 [29].…”

Influence of Salinity and Pb on the Precipitation of Zn in a Model System

“…Bechererite has six octahedrally coordinated cations, and every seventh octahedron is vacant. Furthermore, two tetrahedrally coordinated Zn cations form a pyrogroup leading to a very ordered structure of this mineral phase [29]. Therefore, bechererite can be excluded as an exchange product of gordaite.…”

“…According to Hawthorne and Sokolova [29], the structures of gordaite, namuwite, and bechererite are closely related as they all contain alternating sheets with octahedral and tetrahedral sites (homeomorphic to graph 4b of Hawthore and Schindler [40]). Figure 10 shows the generic structure for gordaite and namuwite.…”

“…In order to assign and verify the phases in XRD and FTIR spectroscopy, we considered various literature dealing with possible Pb and Zn compounds, such as phases observed in specific locations such as Laurion, Greece [28], investigated for crystal structure and chemistry (e.g., [29][30][31][32]), or found as corrosion products (e.g., [33]). …”