Interlayer sodium ions of montmorillonite were exchanged with hydroxy-bismuth polycations which were prepared from bismuth perchlorate solutions by the addition of NaOH. Assuming the charge density of the silicate layer to be unchanged, the compositions of the polycations involved in the exchange can be estimated from the amount of bismuth taken up by the montmorillonite and from the ignition loss between 110° and 800°C. The derived compositions are near [Bi6(OH)16]2+ irrespective of the ratio of OH:Bi in the perchlorate solution. The basal spacing of the hydroxy-bismuth montmorillonites is about 16 Å at 110°C, which corresponds to that of hydroxy-chromium montmorillonite having a high surface area of about 250 m2/g. The surface areas of the hydroxy-bismuth montmorillonites, however, are less than 80 m2/g.

This work is an investigation of the assemblages of supergene minerals occurring in hydrothermal REE–U–Au quartz-vein mineralisation at the Prakovce-Zimná Voda site, Slovakia. Heterogeneous uranyl arsenates and minor phosphates of the autunite group (nováčekite, kahlerite, threadgoldite, autunite, arsenuranospathite and chistyakovaite) together with scorodite and Sb–Bi-rich philipsbornite–segnitite-series minerals formed by oxidising fluids during decomposition and leaching of primary hypogene uraninite, brannerite and base-metal sulfides and sulfosalts. A progressive change of pH from acidic to near-neutral due to the gradual consumption of sulfides resulted in the formation of late phosphuranylite, pharmacosiderite and arseniosiderite. Goethite and other Fe oxides represent the latest hydrous ferric mineral phases and were formed after most of the As was already fixed in Fe arsenates. Antimony and Bi were taken up only into philipsbornite–segnitite and suggest unusual conditions during this process. X-ray absorption spectroscopy indicates that Sb in the philipsbornite–segnitite is fully oxidised (0.1–0.4 apfu Sb5+, octahedral coordination on the G site). Pentavalent Sb together with the presence of ferric oxides and arsenates and uranyl minerals suggest oxidative conditions during weathering. This study also indicates that hydrous ferric arsenates are dominant and stable secondary minerals in a supergene environment in a quartz vein rich in Fe and As accompanied by elevated concentrations of U, Pb, Sb, Bi, S, P, Ca and Ba under oxidising conditions.

A high-grade ore sample from the Cu–Zn–Au Photo Lake volcanogenic massive sulfide deposit (Flin Flon–Snow Lake greenstone belt, Manitoba, Canada) contains a Bi–Ag sulfo-selenide with a composition situated approximately in the middle of the S–Se substitution range (Se ≈ 0.86 apfu and S ≈ 1.05 apfu). These new data, combined with a literature compilation of all publicly available matildite and bohdanowiczite compositional data, reveal a nearly complete range of S–Se substitution between these two minerals, with only the section between BiAgSe0.78S1.18 and BiAgSe0.25S1.75 – about a quarter of the complete S–Se range – not yet documented. These observations suggest that a complete solid-solution series between matildite and bohdanowiczite, as previously suspected, might exist and in a manner similar to the galena–clausthalite complete solid-solution series.

Materials that show superior light-emitting and catalytic properties are in high demand among the scientific community owing to their applications in the areas of optoelectronics and (opto)electrocatalysis. In this work, we have synthesized sub-10-nm Pr2Sn2O7 (PSO) and Pr2Sn2O7:Bi3+ (PSOB) nanoparticles (NPs) and investigated their optical and electrochemical properties. On ultraviolet irradiation, PSO NPs display blue emission because of the presence of oxygen vacancies. Interestingly, PSOB NPs have higher blue emission intensity than undoped PSO NPs owing to the increase in oxygen vacancy defect density induced by Bi3+ doping. Moreover, PSOB NPs display higher efficiency in terms of current density than PSO NPs as a catalyst toward the oxygen evolution reaction (OER). The kinetic OER models of PSO and PSOB NPs are quite different as displayed by their different Tafel slopes. Interestingly and as another advantage, the PSOB sample is more conducting with low impedance value than the PSO counterpart. With all these advantages due to high oxygen vacancies induced by Bi3+ doping, PSOB NPs have a great potential to be used as blue phosphors, charge storage devices, and capacitors.

Electrochemical reduction of CO2 to formic acid is a good strategy to address both environmental and energy issues. However, some drawbacks including low activity, selectivity, and stability of electrocatalysts must be overcome. We propose a method for tailoring Bi2O2CO3-coated carbon fiber electrodes with higher selectivity and stability for electrochemical CO2 reduction to formic acid. We evaluated the effect of Bi2O2CO3 and Nafion contents on the electrocatalysts performance for CO2 reduction reaction (CO2RR). All electrodes produced only HCOO− in the liquid phase with a maximum faradaic efficiency (FE) of 69%. The electrocatalysts were stable under 24 h of continuous CO2RR operation. The FE increased with the increasing electrolyte concentration and cation radius size, which indicates that the anion stabilization in solution is critical for adequate formate generation. The CO2RR mechanism was proposed with basis on the literature. The structural carbonate of Bi2O2CO3 acts as an intermediate species in the formate production from CO2.

Demicheleite-(I), ideally BiSI, is the iodine-dominant analogue of demicheleite-(Br) and demicheleite-(Cl). It was found in an active medium-temperature intracrateric fumarole at La Fossa crater, Vulcano Island, Aeolian archipelago, Sicily, Italy. The mineral is the first bismuth sulphoiodide so far discovered in a wholly natural environment, and corresponds to the already known synthetic compound. It occurs as acicular to stout, translucent crystals up to 0.25 mm long in an altered pyroclastic breccia, together with demicheleite-(Br), bismoclite, bismuthinite, godovikovite, panichiite, aiolosite, brontesite, adranosite and other new phases under study. The colour is dark red to black, the lustre submetallic. The unit cell is orthorhombic, space group Pnam, with a = 8.4501(7) Å, b = 10.1470(9) Å , c = 4.1389(4) Å , V = 354.88(4) Å3, and Z = 4. The crystal habit is prismatic, with the main forms {110} and {111} inferred from analogy with demicheleite-(Br). Twinning was not observed. The strongest 6 lines in the X-ray powder diffraction pattern [dobs.(Å) (I/I0) (hkl)] are: 6.490 (100) (110); 4.346 (94) (120); 3.896 (90) (210); 2.709 (60) (310); 2.161 (38) (330); 3.243 (22) (220). The chemical analysis obtained by WDS electron microprobe gave: Bi 58.32, S 9.43, I 23.69, Br 5.66, Cl 1.01, totalling 98.11 wt.%, corresponding to an empirical formula (based on 3 a.p.f.u.) of: Bi0.97S1.03(I0.65Br0.25Cl0.10)Σ1.00. The unit-cell data are close to those of the synthetic compound, whose crystal structure is already known. The calculated density is 6.411 g cm–3.

Kusachiite, CuBi2O4, has been found in a calcite vein cutting gehlenite-spurrite skarns at Fuka, Okayama Prefecture. It is associated with calcite, henmilite, sillenite, bakerite, tenolite, bultfonteinite, apophyllite, cuspidine and thaumasite. Kusachiite occurs as prismatic crystals or globular aggregates of platy crystals. It is black, opaque with a metallic lustre. Kusachiite is tetragonal with space group P4/ncc, a = 8.511(2), c = 5.823(2) Å, Z = 4. The strongest lines in the X-ray powder pattern [d in Å (I)(hkl)] are 3.191 (100)(211), 2.695 (18)(310), 1.947 (18)(411), 4.26 (17)(200), 2.913 (16)(002), 2.404 (13)(202), 1.728 (12)(213), and 1.652 (9)(332). The Mohs hardness is 4.5, and the density is 8.5(3) g/cm3 (meas.) and 8.64 g/cm3 (calc.). Cleavage is perfect on {110}. Six electron probe analyses gave the following mean values CuO 13.91, Bi2O3 86.00 and total 99.91 in wt.%. The empirical formula calculated on the basis of O = 4 is Cu0.960Bi2.027O4 with the simplified formula CuBi2O4.

Markhininite, ideally TlBi(SO4)2, was found in a fumarole of the 1st cinder cone of the North Breach of the Great Fissure Tolbachik volcano eruption (1975–1976), Kamchatka Peninsula, Russia. Markhininite occurs as white pseudohexagonal plates associated with shcherbinaite, pauflerite, bobjonesite, karpovite, evdokimovite and microcrystalline Mg, Al, Fe and Na sulfates. Markhininite is triclinic, P, a = 7.378(3), b = 10.657(3), c = 10.657(3) Å , α = 61.31(3), β = 70.964(7), γ = 70.964(7)º, V = 680.2(4) Å3, Z = 4 (from single-crystal diffraction data). The eight strongest lines of the X-ray powder diffraction pattern are (I/d/hkl): 68/4.264/111, 100/3.441/113, 35/3.350/222, 24/3.125/122, 23/3.054/202, 45/2.717/022, 20/2.217/331, 34/2.114/204. Chemical composition determined by electron microprobe analysis is (wt.%): Tl2O 35.41, Bi2O3 38.91, SO3 25.19, total 99.51. The empirical formula based on 8 O a.p.f.u. is Tl1.04Bi1.05S1.97O8. The simplified formula is TlBi(SO4)2, which requires Tl2O 35.08, Bi2O3 38.48, SO3 26.44, total 100.00 wt.%. The crystal structure was solved by direct methods and refined to R1 = 0.055 on the basis of 1425 independent observed reflections. The structure contains four Tl+ and two Bi3+ sites in holodirected symmetrical coordination. BiO8 tetragonal antiprisms and SO4 tetrahedra in markhininite share common O atoms to produce [Bi(SO4)2]– layers of the yavapaiite type. The layers are parallel to (111) and linked together through interlayer Tl+ cations. The mineral is named in honour of Professor Yevgeniy Konstantinovich Markhinin (b. 1926), Institute of Volcanology, Russian Academy of Sciences, Kamchatka peninsula, Russia, in recognition of his contributions to volcanology. Markhininite is the first oxysalt compound that contains both Tl and Bi in an ordered crystal structure.

Cannonite, ideally Bi2O(OH)2SO4, is a new mineral from the Tunnel Extension mine, Ohio Mining District, Marysvale, Utah, USA. It occurs mostly as intergrown crystalline aggregates (<1 mm) of subhedral to euhedral equant to prismatic crystals (<200 μm) in cavities in quartz gangue. Other associated minerals are cuprobismutite, bismuthinite, and covelline. Cannonite is colourless and transparent with an adamantine lustre and white streak. It is brittle with an uneven to conchoidal fracture. In reflected light it is low reflecting, weakly to moderately bireflectant and weakly anisotropic. Internal reflections (colourless to white) are abundant. Measured reflectance values in air and oil are tabulated. Colour values relative to the CIE illuminant C for R1 and R2 in air respectively are: Y% 10.4, 11.7; Lambdad 475,475; Pe% 2.6, 3.0. Calculated refractive indices at 589 nm: R1 1.91 and R2 1.99. VHN100 229 (range 183-280); calculated Mohs hardness is 4.

X-ray studies show that cannonite is monoclinic with space group P21/c and a 7.700(3), b 13.839(6), c 5.686(2) Å, β 109.11(3) ° It has a cell volume of 572.5(4) Å3 with Z = 4. Dcalc. is 6.515 g/cm3. The strongest six lines of the X-ray powder pattern are [d in Å (I) (hkl)] 3.206 (100) (221); 1.984 (90) (340, 152); 2.924 (70) (131); 3.644 (60) (111); 3.466 (60) (040); 2.782 (50) (112). Averaged probe analyses gave the empirical formula Bi1.99O(OH1.04)2S0.99O4 on the basis of 7 oxygen atoms. The name is for Benjamin Bartlett Cannon of Seattle, Washington, United States of America.

We have analysed a rare occurrence of orange-brown manganotantalite lamellae (visible in hand specimen), intergrown with microlite [(Ca,Na)2(Ta,Nb)2(O,OH,F)7], aggregates of ferrotapiolite, bismuth minerals and apatite to understand more about the mechanisms of crystal growth and secondary modification in Ta-rich minerals. The intergrowth occurs within amblygonite/montebrasite nodules near the quartz core of the highly fractionated rare-metal Li/Be/Ta pegmatite at Rubicon, Karibib, Namibia. Electron microprobe analyses show that manganotantalite lamellae are variable in composition. Primary microlite (Ta2O5 82%, 1.97 Ta a.p.f.u.) forms the matrix mineral between the lamellae. Textural relations suggest an exsolution origin for the lamellae. Manganotantalite is represented by three generations: (1) primary late magmatic; (2) disequilibrium exsolution lamellae; and (3) subsolidus replacement. Crystallization commenced with primary microlite and likely simultaneous intergrowth between ferrotapiolite and a first generation of late-magmatic primary manganotantalite with low Ta (1.1—1.5 a.p.f.u.). On cooling this was followed by exsolution of manganotantalite lamellae, generation (2) with low—medium Ta (1.27—1.7 a.p.f.u.). The replacement of microlite by a highly fractionated late-stage melt rich in Mn2+, Ca2+ with low Na+ finally produces a third generation (3) of manganotantalite with high Ta (1.72—1.99 a.p.f.u.) at the contact with microlite. Native bismuth and bismutite cut across microlite and pseudomorph lamellae as a final hydrothermal replacement. Apatite is ubiquitous at the contact with amblygonite. The stability field of microlite may be extended by incorporation of CaTa2O6-rynersonite and Ca2Ta2O7 — idealized, components in solid solution. However, rynersonite-CaTa2O6 with distorted octahedra has some structural templates which are similar to the structure of pyrochlore (microlite). Hence, via the perovskite/pyrochlore analogy, hypothetical exsolution of manganotantalite-type structures may occur from a microlite (pyrochlore) host by solid-state diffusion via metastable rynersonite-type intermediates. Such a mechanism has the potential to explain the crystallographically controlled intergrowth textures and the compositional heterogeneity.

The accuracy to which Cu and Al coatings can be determined, and the effect this has on the quantification of the substrate, is investigated. Cu and Al coatings of nominally 5, 10, 15, and 20 nm were sputter coated onto polished Bi using two configurations of coater: One with the film thickness monitor (FTM) sensor colocated with the samples, and one where the sensor is located to one side. The FTM thicknesses are compared against those calculated from measured Cu Lα and Al Kα k-ratios using PENEPMA, GMRFilm, and DTSA-II. Selected samples were also cross-sectioned using focused ion beam. Both systems produced repeatable coatings, the thickest coating being approximately four times the thinnest coating. The side-located FTM sensor indicated thicknesses less than half those of the software modeled results, propagating on to 70% errors in substrate quantification at 5 kV. The colocated FTM sensor produced errors in film thickness and substrate quantification of 10–20%. Over the range of film thicknesses and accelerating voltages modeled both the substrate and coating k-ratios can be approximated by linear trends as functions of film thickness. The Al films were found to have a reduced density of ~2 g/cm2.

The new mineral tavagnascoite, Bi4O4 (SO4)(OH)2, was discovered in the Pb-Bi-Zn-As-Fe-Cu ore district of Tavagnasco, Turin, Piedmont, Italy. It occurs as blocky, colourless crystals, up to 40 μm in size, with a silky lustre. In the specimen studied, tavagnascoite is associated with other uncharacterized secondary Bi-minerals originating from the alteration of a bismuthinite ± Bi-sulfosalt assemblage. Electron microprobe analyses gave (average of three spot analyses, wt.%) Bi2O3 85.32, Sb2O3 0.58, PbO 2.18, SO3 8.46, H2Ocalc 1.77, sum 98.31. On the basis of 10 O apfu, the chemical formula is (Bi3.74Pb0.10Sb0.04)∑ = 3.88O3.68 (SO4)1.08(OH)2, with rounding errors. Main calculated diffraction lines are [d in Å (relative intensity) hkl] 6.39 (29) 012, 4.95 (19) 111,4.019(32)121,3.604(28)014 and 3.213(100)123. Unit-cell parameters are a = 5.831(1), b = 11.925(2), c = 15.123(1) Å, V = 1051.6(3) Å3, Z = 4, space group Pca21. The crystal structure was solved and refined from single-crystal X-ray diffraction data to R 1 = 0.037 on the basis of 1269 observed reflections. It consists of Bi–O polyhedra and SO4 tetrahedra. Bismuth polyhedra are connected each to other to form Bi–O sheets parallel to (001). Successive sheets are linked together by SO4 groups and hydrogen bonds. Tavagnascoite is the Bi-analogue of klebelsbergite, Sb4O4(SO4)(OH)2, and it is the fifth natural known bismuth sulfate without additional cations. The mineral and its name have been approved by the IMA CNMNC (2014-099).

Photovoltaics made from organic–inorganic hybrid perovskite semiconductors are attracting significant interest due to their ability to harvest sunlight with remarkable efficiency. The presence of lead in the best performing devices raises concerns regarding their toxicity, a problem that may create barriers to commercialization. Hybrid perovskites with reduced lead content are being investigated to overcome this issue and here we evaluate bismuth as a possible lead substitute. For a series of hybrid perovskite films with the general composition CH3NH3(Pb y Bi1−y )I3−x Cl x , we characterize their optical and structural properties using UV–Vis spectroscopy, scanning electron microscopy and grazing incidence wide angle X-ray scattering. We show that they form crystalline structures with an optical band gap, around 2 eV for CH3NH3BiI3. However, preliminary solar cell tests show low power conversion efficiencies (<0.01%) due to both incomplete precursor conversion and material de-wetting from the substrate. The overall outcome is severely limited photocurrent. With current processing methods the general applicability of hybrid bismuth perovskites in photovoltaics may be limited.

The nature of nanocrystalline inclusions and dopant distribution in bismuth-doped silicate fibers and preforms are studied by scanning and transmission electron microscopy, and energy and wavelength-dispersive X-ray microanalysis. The core compositions are Bi:SiO2, Bi:Al2O3–SiO2, Bi:GeO2–SiO2, Bi:Al2O3–GeO2–SiO2, and Bi:P2O5–Al2O3–GeO2–SiO2. Nanocrystals of metallic Bi, Bi2O3, SiO2, GeO2, and Bi4(GeO4)3 are observed in these glasses. These inclusions can be the reason for the background optical loss in bismuth-doped optical fibers. The bismuth concentration of 0.0048±0.0006 at% is directly measured in aluminosilicate optical fibers with effective laser generation (slope efficiency of 27% at room temperature).

Nanowires of bismuth with diameters ranging from 10 to 200 nm and lengths of 50 μm have been synthesized by a pressure injection method. Nanostructural and chemical compositional studies using environmental and high resolution transmission electron microscopy with electron stimulated energy dispersive X-ray spectroscopy have revealed essentially single crystal nanowires. The high resolution studies have shown that the nanowires contain amorphous Bi-oxide layers of a few nanometers on the surface. In situ environmental high resolution transmission electron microscopy (environmental-HRTEM) studies at the atomic level, in controlled hydrogen and other reducing gas environments at high temperatures demonstrate that gas reduction can be successfully applied to remove the oxide nanolayers and to maintain the dimensional and structural uniformity of the nanowires, which is key to attaining low electrical contact resistance.