Additional data on reevesite and its Co-analogue, as a new member of the hydrotalcite group

Abstract

Reevesite, the Ni-Fe member of the hydrotalcite group, occurs as a secondary mineral in the serpentinized ultramafic rocks of the Kwangcheon area in Korea, replacing the pecoraitc-magnetite-millerite-polydymite assemblages in small veins lining cracks and fracture zones. Chemical analyses for the reevesites indicate the presence of the Co-analogue of reevesite and the complete solid-solution between Fe3+and Co3+. The Co-analogue of the reevesite shows the approximate ratio of 3:1 of divalent to trivalent cations, which is in distinct contrast to the comblainite with the ratio of 2:1 reported by Piret & Deliens (1980). The presence of the complete solid-solution phase between Fe3+and Co3+is confirmed by synthesis at room temperature. On the basis of the results, the Co-analogue of the reevesite should be named as a new member of the hydrotalcite group, and thereby be distinguished from the comblainite. The partial substitutions of SO2-4for CO2-3in the interlayer region might affect the slight increase of the basal spacing in the reevesite. The synthesis performed suggests that the reevesite could be precipitated under either an alkaline or a neutral environment, if carbonate activity is high enough.

Surface Engineering of Graphene Oxide Shells Using Lamellar LDH Nanostructures

“…The occurrence of d (003) = 2d (006) = 3d (009) suggests the formation of layered structure of LDH lamellae self-assembled radially on rGO. The presence of asymmetric reflection at 33.6 suggests the presence of stacking faults reported in the LDHs . The sharp (003) peak and symmetric narrow bands of the Ni–Co LDH@rGO suggest that these synthesis conditions can be used to achieve high crystallinity in LDH lamellae on rGO shells.…”

Crystal Structure of Hydrotalcite Group Mineral—Desautelsite, Mg6MnIII2(OH)16(CO3)·4H2O, and Relationship between Cation Size and In-Plane Unit Cell Parameter

“…Obviously, the weak crystal-chemical characteristics of many minerals of the hydrotalcite supergroup, including the hydrotalcite group itself (Table 7), still remain a problematic side. The correlation between averaged cation radii of metals constructing the octahedral sheet and the in-plane a unit cell parameter for hydrotalcite group minerals using data reported therein and in [11,25,31,32,36,37,39,41,42]. Note: the data without chemical composition are not included; droninoite [43] is omitted since Fe 2+ /Fe 3+ is not known.…”

“…The following supporting information can be downloaded at: www.mdpi.com/xxx/s1, Table S1: powder X-ray diffraction data for desautelsite sample 80137 including reflections of lizardite and dashkovaite and Table S2: anisotropic displacement parameters (Å 2 ) for desautelsite. The correlation between averaged cation radii of metals constructing the octahedral sheet and the in-plane a unit cell parameter for hydrotalcite group minerals using data reported therein and in [11,25,31,32,36,37,39,41,42]. Note: the data without chemical composition are not included; droninoite [43] is omitted since Fe 2+ /Fe 3+ is not known.…”

“…Figure7. The correlation between averaged cation radii of metals constructing the octahedral sheet and the in-plane a unit cell parameter for hydrotalcite group minerals using data reported therein and in[11,25,31,32,36,37,39,41,42]. Note: the data without chemical composition are not included; droninoite[43] is omitted since Fe 2+ /Fe 3+ is not known.…”