CsPbBr3 and CsPbI3 rhombic dodecahedra and nanocubes displaying facet-dependent optical properties

CsPbBr3 rhombic dodecahedra, octahedra, and nanocubes have been synthesized using typical reagents but by adjusting the amounts of organic capping molecules used and the reaction temperature. Although some Cs4PbBr6 has...

Formation of size-tunable CdS rhombic dodecahedra

By preparing an aqueous solution of cadmium acetate, thioacetamide (TAA), and nitric acid at 23 to 29 ºC, then heating the solution to 110 ºC for 40 min, unprecedented {110}-bound...

Temperature dependent crystallization of Cu2O rhombic dodecahedra

Size and shape uniformity of nanomaterials are extremely important for their applications in batteries, supercapacitors, catalysis, etc. In the crystallization process, finding proper synthesis condition is necessary to control over...

Hydroflux syntheses and crystal structures of hydrogarnets Ba3[RE(OH)6]2 (RE = Sc, Y, Ho–Lu)

Colorless crystals of the barium rare earth hydrogarnets Ba3[RE(OH)6]2 (RE = Sc, Y, Ho–Lu) were synthesized under hydroflux conditions with KOH at about T = 200 °C starting from the respective RE2O3 and Ba (NO3)2. Single-crystal X-ray diffraction analysis on these distorted rhombic dodecahedra revealed the cubic space group Ia$‾{3}$d (no. 230). The crystal structures of the hydrogarnets Ba3[RE(OH)6]2 are discussed and compared with those of other hydrogarnets. The occurrence of additional reflections, which do not fulfill the reflection conditions of Ia$‾{3}$d, is analyzed and described by Renninger or λ/2 effects. A correlation is established between the space group adopted by a hydrogarnet and characteristic interatomic distances. In addition, single-crystal structure data of the strontium indium hydrogarnet Sr3[In(OH)6]2 are provided.

Hydroxyplumbopyrochlore, (Pb1.5,□0.5)Nb2O6(OH), a new member of the pyrochlore group from Jabal Sayid, Saudi Arabia

ABSTRACTA new mineral species of the pyrochlore supergroup, hydroxyplumbopyrochlore (IMA2018-145), (Pb1.5,□0.5)Nb2O6(OH), has been discovered in the Jabal Sayid peralkaline granitic complex of the Arabian Shield, Saudi Arabia. It is associated with quartz, microcline, ‘biotite’, rutile, zircon, calcite, rhodochrosite, columbite-(Fe), goethite, thorite, bastnäsite-(Ce), xenotime-(Y), samarskite-(Y), euxenite-(Y), hydropyrochlore and fluornatropyrochlore. Hydroxyplumbopyrochlore usually shows euhedral octahedra, slightly rhombic dodecahedra and cubes or their combination (0.01–0.06 mm). The mineral is pale yellow to pale brown, transparent with white streak, and has adamantine to transparent lustre. It is brittle with conchoidal fracture. No cleavage or parting are observed. It is isotropic and non-fluorescent. The average microhardness is 463.4 kg mm–2. The calculated density is 6.474 g cm–3.Hydroxyplumbopyrochlore belongs to the cubic crystal system and exhibits the space group Fd$\bar{3}$m with unit-cell parameters a = 10.5456(6) Å, V = 1172.8(2) Å3 and Z = 8. Electron microprobe analysis gave (6-point average composition, wt.%): CaO 0.32, SrO 0.16, FeO 0.17, Ce2O3 0.07, Pr2O3 0.02, PbO 51.69, Nb2O5 40.06, SiO2 0.05, TiO2 1.68, Ta2O5 4.74, H2Ocalc 0.95, total 99.90, yielding the empirical formula (Pb1.34Ca0.03Fe0.01Sr0.01□0.61)Σ2(Nb1.75Ti0.12Ta0.12Si0.01)Σ2O6(OH0.53O0.08□0.39)Σ1, where □ = vacancy. The Raman spectrum of hydroxyplumbopyrochlore contains the characteristic bands of O–H vibrations and no bands for H2O vibrations.

Cu2O polyhedra for aryl alkyne homocoupling reactions

Cu2O rhombic dodecahedra display good catalytic activities toward diverse aryl alkyne homocoupling reactions.