Crystal structure of sodium alumosilicate cyanide, Na-8[AlSiO4](6)(CN)(2)

Al6C2N2Na8O24Si6, cubic, P (4) over bar 3n (No. 218), a = 8.9192(1) Angstrom, V = 709.5 Angstrom(3), Z = 1, R(P) = 0.036, R(I) = 0.020, T = 293 K

Symmetry reduction due to gallium substitution in the garnet Li6.43(2)Ga0.52(3)La2.67(4)Zr2O12

Single-crystal structure refinements on lithium lanthanum zirconate (LLZO; Li7La3Zr2O12) substituted with gallium were successfully carried out in the cubic symmetry space group I [Formula: see text]3d. Gallium was found on two lithium sites as well as on the lanthanum position. Due to the structural distortion of the resulting Li6.43(2)Ga0.52(3)La2.67(4)Zr2O12 (Ga-LLZO) single crystals, a reduction of the LLZO cubic garnet symmetry from Ia[Formula: see text] d to I [Formula: see text]3d was necessary, which could hardly be analysed from X-ray powder diffraction data.DFG/TMG/GE1981/31DFG/TMG/GE1981/32Niedersächsisches Ministerium für Wissenschaft und Kultur (MWK)/PH/74ZN99

Guanidinium tetra­bromidomercurate(II)

The Hg atoms in the crystal structure of the title compound, (CH6N3)2[HgBr4], are tetra­hedrally coordinated by four Br atoms and the resulting [HgBr4]2− tetra­hedral ions are linked to the [C(NH2)3]+ ions by bromine–hydrogen bonds, forming a three-dimensional network. In the structure, the anions are located on special positions. The two different Hg⋯Br distances of 2.664 (1) and 2.559 (1) Å observed in the tetra­bromidomercurate unit are due to the connection of Br atoms to different number of H atoms

Bis(guanidinium) tetra­iodidomercurate(II)

The Hg atom in the crystal structure of the title compound, (CH6N3)2[HgI4], is tetra­hedrally coordinated by four I atoms. The [HgI4]2− ions are inter­connected to the [C(NH2)3]+ ions by N—H⋯I hydrogen bonds, forming a three-dimensional network. The four different observed Hg—I distances [2.760 (2), 2.7762 (15), 2.8098 (14) and 2.833 (2) Å] are consistent with four different 127I NQR frequencies observed, showing the existence of four unique I atoms in the tetra­iodidomercurate unit

Strontium doping in mullite-type bismuth aluminate: A vacancy investigation using neutrons, photons and electrons

We report on strontium doped dibismuth-nonaoxoaluminate(III) produced at 1023 K. Partial substitution of bismuth by strontium in the structure yields oxygen vacancies for charge balance. Introducing oxygen vacancies rearranged the associated Al2O7 double-tetrahedra forming “Al3O10” tri-clusters which were identified by multi-quantum 27Al MAS NMR. Both STEM-EDX and XPS showed homogeneous distribution of strontium in the bulk and on the surface, respectively. Moreover, XPS confirms the valence state of bismuth after doping. The orientations of bismuth 6s2 lone electron pairs were calculated using DFT methods. The amount of strontium in the crystal structure was further confirmed from the decomposition product SrAl12O19 formed during the temperature-dependent X-ray powder diffraction. The structural proof was carried out by refining the structure of (Bi0.94Sr0.06)2Al4O8.94 from powder neutron and X-ray diffraction data. Rietveld refinements clearly showed the under occupation of one oxygen site and the shift of two aluminum atoms from the double-tetrahedra to two tri-cluster sites

Crystal chemical characterization of mullite-type aluminum borate compounds

Al-rich aluminum borates were prepared by different synthesis routes using various Al/B ratios, characterized by diffraction methods, spectroscopy and prompt gamma activation analysis. The 11B NMR data show a small amount of BO4 species in all samples. The chemical analysis indicates a trend in the Al/B ratio instead of a fixed composition. Both methods indicate a solid solution Al5−xB1+xO9 where Al is substituted by B in the range of 1–3%. The structure of B-rich Al4B2O9 (C2/m, a=1488 pm, b=553 pm, c=1502 pm, ß=90.6°), was re-investigated by electron diffraction methods, showing that structural details vary within a crystallite. In most of the domains the atoms are orderly distributed, showing no signal for the postulated channel oxygen atom O5. The absence of O5 is supported by density functional theory calculations. Other domains show a probable disordered configuration of O5 and O10, indicated by diffuse scattering along the b direction.17318

Electrochemical rutile and anatase formation on PEO surfaces

A highly porous surface with a high crystalline content and resultant photocatalytic activity is ensured through the process of plasma electrolytic oxidation on pure titanium. In the present study the morphology, crystallinity and photocatalytic activity of plasma electrolytic oxidized TiO2-surfaces were investigated. The surfaces were prepared in acidic and alkaline electrolytes over an applied voltage range between 50 V and 300 V to optimize the crystalline and photocatalytic properties. Scanning electron microscopy (SEM) and X-ray powder diffraction (XRD) were selected to determine the morphologies which differ according to the type of electrolyte as well as the crystal structures of anatase and rutile on the surface material, which increase with the applied voltage. The oxide surfaces did not show morphological differences compared to typical PEO surfaces with the exception of oxide films obtained in H2SO4-solution which also exhibited an astounding amount of rutile even with low applied voltages. The increased parts of anatase and rutile on the surfaces resulted in photocatalytic activity, which was investigated under UV-light using methylene blue, while the PEO surfaces showed degradation activity. There is an indication that a high proportion of anatase and small amounts of rutile in the PEO layers positively influence photocatalytic activity.13914

Crystal structure of rubidium niobium tungsten bronzes, RbxNbyW1-yO3(x~0.3;y=0.13,0.19)

[no abstract

Crystal structure of caesium niobium tungsten bronzes, Cs-0.23(Nb0.09W0.91)O-3 andCs(0.29)(Nb0.10W0.90)O-3

Cso.23Nbo.09O3Wo.91 (1) hexagonal, P63/mcm (No. 193), a = 7.3998(2) Å, c = 7.5732(2) Å, V = 359.1 ų, Ζ = 6, wR(P) =0.062, R(P)=0.044,R(I)=0.023, R(F)=0.012, T= 293 K. Cs0.29Nb0.10O3W0.90 (2), hexagonal, P63/mcm (No. 193), a = 7.3992(2) Å, c = 7.5867(2) Å, V = 359.7 ų, Ζ = 6, wR(P)=0.080, R(P)=0.057, R(I)=0.028, R(F)=0.014, T= 293 K

Role of the precursor chemistry on the phase composition and electrochemical performance of thin-film LiMn2O4 Li-ion battery cathodes prepared by spray pyrolysis

LiMn2O4-films were prepared by air-blast spray pyrolysis directly onto stainless steel foil substrate. The films were synthesized from various precursor solutions of dissolved nitrates and acetates with and without the addition of polyethylene glycol (PEG). Hereby X-ray diffraction experiments revealed that the phase compositions of the as-prepared and thermally post-treated films were highly dependent on the precursors used, but independent of the addition of PEG. Samples prepared from nitrates yielded phase mixtures of α-Mn2O3, Mn3O4 and LiNO3 as-prepared and LiMn2O4 and α-Mn2O3 after post-thermal treatment. Whereas films sprayed from acetate precursors consisted of LiMn2O4 predominantly before and after heat treatment, as well. Scanning electron microscopy investigations showed that the applied precursor had an effect on the film morphology and the addition of PEG led to film thinning. Galvanostatic cycling tests and post-mortem analyses of the electrochemical cell s fabricated from the thermally treated thin layers revealed that the film prepared from acetates and PEG had the highest capacity retention despite the formation of orthorhombic LiMnO2 besides the cubic LiMn2O4 during battery cycling