A Solution to the Crystal Structures of Bismutite and Beyerite

Abstract

The crystal structures of bismutite, Bi 2 (CO 3 )O 2 , a 3.865(2), b 3.862(2), c 13.675(6) Å, V 204.1(2) Å 3 , space group Imm2, Z = 2, and beyerite, CaBi 2 (CO 3 ) 2 O 2 , a 3.7729(5), b 3.7742(7), c 21.726(4) Å, V 309.4(1) Å 3 , space group Immm, Z = 2, have been refined to R indices of 0.0206 and 0.0145 on the basis of 184 and 258 unique reflections. Although the cell and the distribution of diffraction intensities obey tetragonal symmetry, for both these minerals, attempts to solve the structure with tetragonal symmetry led to stereochemical problems. Introduction of a twin plane via reflection on {110} for orthorhombic symmetry simulates tetragonal diffraction-intensity distribution for the peudo-merohedral twin, and gives a structure with sensible stereochemistry. All large cations, Ca and Bi, have [8]-coordination, and Bi 3+ shows stereoactive lone-pair behavior. The structures are layered with Bi-O layers, a Ca-O layer in beyerite and (CO 3 ) layers with the plane of the (CO 3 ) group orthogonal to the plane of the layer. Bismutite and beyerite have crystal structures typical of "Sillén" phases, and they are closely related structurally to the only other Bi oxycarbonate mineral, kettnerite.Keywords: bismutite, beyerite, crystal structure, pseudo-merohedral twin, stereoactive lone-pair of electrons, oxycarbonate. , l'orientation des groupes (CO 3 ) étant orthogonale par rapport au plan des couches. Du point de vue structural, la bismutite et la béyerite sont typiques des phases dites de "Sillén", et elles ressemblent à la seule phase minérale oxycarbonatée de bismuth, la kettnerite. (Traduit par la Rédaction)Mots-clés: bismutite, béyerite, structure cristalline, macle par pseudo-méroédrie, paire isolée d'électrons stéréoactive, oxycarbonate.

Electric relaxation and Mn3+/Mn4+ charge transfer in Fe-doped Bi12MnO20–BiMn2O5 structural self-composite

“…However, the line placed at *32°in the XRD pattern vanished. We deduce that a residual amount of additional compound, resulting probably from not fully reacted substrates, most likely bismuth carbonate (BiO) 2 CO 3 , that were removed after the sample was thermally treated [15,36,37]. Moreover, the disorder increased slightly, since the FWHM of the (112) line from Pbam symmetry and (400) line from I23 symmetry, e.g., placed at 35.77(2)°changed by 0.08.…”

Ultrasonic-assisted synthesis of amorphous Bi2S3 coupled (BiO)2CO3 catalyst with improved visible light-responsive photocatalytic activity

“…Bismuth-containing materials, such as BiOX (X = Cl, Br, I) [16,17], BiVO 4 [18], Bi 2 WO 6 [19], and (BiO) 2 CO 3 [20], exhibit not only good visible light photocatalytic activity but also high chemical stability. Among these materials, the bismuth subcarbonate (BiO) 2 CO 3 which belongs to Aurivillius-related oxide family with a typical ''sillén'' phase structure [20] is particularly efficient for the degradation of organic dyes [21][22][23][24][25] and isopropyl alcohol [22].…”

Solvothermal Synthesis of Bi2O2CO3Nanoplates for Efficient Photodegradation of RhB and Phenol under Simulated Solar Light Irradiation

“…Bi 2 O 2 CO 3 is a typical "Sillén" phase, in which Bi-O layers and (CO 3 ) layers are inter-grown with the plane of the (CO 3 ) group orthogonal to the plane of the Bi-O layer. 21,22 The internal layered structure of Bi 2 O 2 CO 3 would guide the lower growth rate along certain axis compared with that for other axes, to form 2D morphologies such as sheet-like or plate-like products. 8,23,24 Previous work has demonstrated that Bi 2 O 2 CO 3 hierarchical structures assembled by nanosheets exhibit high activity towards the photodegradation of RhB as well as the mixed solution of MB and MO, due to their exposed (001) facets.…”