[Bi2O2]2+ Layers in Bi2O2(OH)(NO3): Synthesis and Structure Determination (original) (raw)
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The paper presents a new data on the crystal structure, thermal expansion and IR spectra of Bi 3 B 5 O 12 . The Bi 3 B 5 O 12 single crystals were grown from the melt of the same stoichiometry by Czochralski technique. The crystal structure of Bi 3 B 5 O 12 was refined in anisotropic approximation using single-crystal X-ray diffraction data. It is orthorhombic, Pnma, a=6.530(4), b=7.726
Journal of Solid State Chemistry, 2003
The bismuth basic nitrate ½Bi 6 O 4:5 ðOHÞ 3:5 2 ðNO 3 Þ 11 crystallizes in the monoclinic space group P2 1 with a ¼ 15:850ð3ÞÅ; b ¼ 14:986ð3ÞÅ; c ¼ 18:230ð4ÞÅ; b ¼ 107:329ð17Þ and V ¼ 4133:7ð14ÞÅ 3 ðZ ¼ 4Þ: Its structure has been determined from 120 K; twinned crystal X-ray data (16 781 reflections, 683 parameters, R ¼ 0:0703). It is built upon ½Bi 6 O x ðOHÞ 8Àx ð10ÀxÞþ ; x ¼ 4 and x ¼ 5 hexanuclear complexes and nitrate groups. The polycationic entities are linked to the nitrate anions either by hydrogen bonds or through bismuth-oxygen coordination. Even at 120 K; the ½Bi 6 O 4 ðOHÞ 4 6þ and ½Bi 6 O 5 ðOHÞ 3 5þ polycations could not be observed as such, the crystal structure refinement only detecting an average ½Bi 6 O 4:5 ðOHÞ 3:5 5:5þ polycation. To prove the presence of both hexanuclear complexes in the structure, we report the existence of a correlation between the bismuth-linked oxygen bond-valence parameters and the presence, or not, of hydroxyl groups. Moreover, the Raman spectrum of the new anhydrous bismuth basic nitrate is compared to those of ½Bi 6 O 5 ðOHÞ 3 ðNO 3 Þ 5 Á 3H 2 O; ½Bi 6 O 4 ðOHÞ 4 ðNO 3 Þ 6 Á 4H 2 O; and two yet uncharacterized bismuth nitrates.
Journal of Solid State Chemistry, 2000
The family of compounds with a structure based on [Bi 12 O 14 ] columns in the Bi 2 O 3 +MoO 3 binary system was analyzed by EDS and studied by TEM. These observations con5rm that this solid solution type is limited within the range 2.64Bi/Mo42.8. The room temperature Bi 26 Mo 10 O 69 triclinic polymorph (Bi/ Mo ؍ 2.6) clearly di4ers from the monoclinic ones (Bi 26 Mo 10 O 69 at T > 3103C and Bi 26 Mo 9 6 Bi 0 4 O 68.4) by the doubling of the a period and the vanishing of a c glide plane.
J Solid State Chem, 1998
WO 3 systems have been investigated using synchrotron X-ray diffraction (XRD) and electron diffraction (ED) to resolve outstanding problems concerning phase relationships, unit cells, and symmetry. A temperature-composition phase diagram for the Bi 2 O 3 -Nb 2 O 5 system is presented. Single-phase powder specimens have been prepared for most phases. A modulated structure approach has been applied to the characterization of phases, and space groups or superspace groups assigned. The most appropriate description (commensurate modulation, incommensurate modulation or superstructure) for the structure of each of the phases is discussed. 1998 Academic Press 42
2020
Thanks to its peculiar structural properties, the high temperature ä-phase of Bi 2 O 3 is considered as the best oxide ion conductor. Many efforts to stabilize this structure at room temperature have been deployed. In the present study, we have successfully stabilized the ä-phase by chemically introducing tetra-Te 4+ and pentavalent Ta 5+ cations into the structure. A series of compounds with different percentage of Te 4+ / Ta 5+ were obtained. Their structural and vibrational properties were investigated. From the Rietveld refinement of X Ray diffraction pattern we show that the composition x = 0.2 crystallizes in the cubic symmetry, space group Fm 3m (ITA No. 225) with a lattice parameter a =5.49 Å. The reliability factors are: R F =2.151 % and R Bragg =2.545 % confirm the goodness of the refinement. From the evolution of Raman bands, we confirm the existence of the solid solution features. Furthermore, comparing the spectra of ä-Bi 2 O 3 with the alpha phase, we comfortably sugge...
A new structure type in the Bi2O3Nb2O5 system
Journal of Solid State Chemistry, 1987
Solid solutions of BizOz and NbZOc encompassing the compositional range from pure BizOl to SB&O, 3NbzOs exhibit a range of complicated ordered structures which are extremely difficult to study by X-ray diffraction methods. High resolution electron microscopy, using previously outlined methodologies, has proved capable of elucidating the structural principles upon which the so-called Type III phase, with a composition of approximately 7BizOi 3Nb205, is based. The structure of this phase is a composite one, built up of limited fluorite, pyrochlore, and perovskite units.
Chemically stabilized δ-Bi2O3 phase: Raman scattering and X-ray diffraction studies
Oriental Journal of Chemistry, 2016
Thanks to its peculiar structural properties, the high temperature ä-phase of Bi 2 O 3 is considered as the best oxide ion conductor. Many efforts to stabilize this structure at room temperature have been deployed. In the present study, we have successfully stabilized the ä-phase by chemically introducing tetra-Te 4+ and pentavalent Ta 5+ cations into the structure. A series of compounds with different percentage of Te 4+ / Ta 5+ were obtained. Their structural and vibrational properties were investigated. From the Rietveld refinement of X Ray diffraction pattern we show that the composition x = 0.2 crystallizes in the cubic symmetry, space group Fm 3m (ITA No. 225) with a lattice parameter a =5.49 Å. The reliability factors are: R F =2.151 % and R Bragg =2.545 % confirm the goodness of the refinement. From the evolution of Raman bands, we confirm the existence of the solid solution features. Furthermore, comparing the spectra of ä-Bi 2 O 3 with the alpha phase, we comfortably suggest that the decrease of the number of Raman bands is a consequence of an increase in the lattice symmetry. Similarly to other fluorite compounds, we show that the structure presents oxygen defects clearly identified in the Raman spectra.
Study of the Formation of Bi2Te4O11
Journal of Solid State Chemistry, 1996
For single-crystal growth of bismuth tellurites it is im-The solid state reaction in a 1 : 4 mole ratio mixture of Bi 2 O 3 portant to know the details of the solid state reaction beand TeO 2 and the polymorphic phase transition of Bi 2 Te 4 O 11 tween Bi 2 O 3 and TeO 2. There are some contradictions in have been investigated using differential scanning calorimetry the published phase diagrams of this reaction (12, 13). In (DSC), electron microprobe, X-ray powder diffraction (XPD), spite of the fact that bismuth tellurites can easily be oxiand selected area electron diffraction (SAED) analysis in the dized in air there are still some open questions concerning 25-730؇C temperature range. Upon heating first a 8Bi 2 Te 4 O 11 ؉ the oxidation process (12-14). Bismuth tellurium oxide 23TeO 2 eutectic is formed, which melts at 598.9؇C. In this melt compounds have anion-deficient fluorite structures. It is the excess of Bi 2 O 3 reacts further and the Bi 2 O 3 ؉ 4TeO 2 ؍ not yet clear whether complete oxidation leading to the Bi 2 Te 4 O 11 reaction takes place. The cubic modification is formed filling of all vacant oxygen sites is possible. by fast crystallization of the Bi 2 Te 4 O 11 melt. The structure of The chemical reaction between Bi 2 O 3 and TeO 2 can be the cubic Bi 2 Te 4 O 11 can be characterized by the lattice constant described by the following equation: of a ؍ 5.6397(5) Å and space group Fm3m. The main product of a slow cooling is the same cubic polymorph although a subordinate formation of the monoclinic phase is also observed. (1 Ϫ x)/2Bi 2 O 3 ϩ xTeO 2 ϭ Bi 1Ϫx Te x O (3ϩx)/2. The -Bi 2 Te 4 O 11 cubic phase undergoes a monotropic transformation into the ␣-Bi 2 Te 4 O 11 monoclinic modification at temper-Bi 2 Te 4 O 11 (x ϭ 0.667) is the first compound formed in the atures higher than 400؇C. The cubic Ǟ monoclinic transition solid state reaction of Bi 2 O 3 and TeO 2. The structure of is the result of an ordering in one set of ͕111͖ planes and the Bi 2 Te 4 O 11 was first studied by Frit et al. (17) and the comorthogonality of the cubic phase in the [110] projection changes plete structure analysis was carried out by Rossel et al. to monoclinic symmetry. The melting enthalpies of the cubic (18). These authors described only the monoclinic Ͱ-modi--phase and the monoclinic ␣-phase are 35.9 ؎ 3.3 J/g and fication. Demina et al. (15) reported on X-ray investigation 84.3 ؎ 4.3 J/g respectively.
Crystal structure of a new stoichiometric compound: Bi2Te5WO16 deriving from fluorite type
Journal of Physics and Chemistry of Solids, 2006
The new Bi 2 Te 5 WO 16 compound has been prepared and its structure has been determined by single crystal X-ray diffraction: space group: P2/n (no. 13) with unit cell parameters a ¼ 11:409ð1ÞÅ, b ¼ 5:673ð1ÞÅ, c ¼ 12:253ð1ÞÅ, b ¼ 116:68ð1Þ1 and Z ¼ 2 formula units. The structure was determined from 1975 reflections, the final R 1 and R w indices are 0.037 and 0.071, respectively. The structure derives from the fluorite structure MX 2 . It can be described as [Bi 2 Te 3 O 12 ] layers parallel to (À1 0 1) alternating in the direction [1 0 À1] by WO 6 octahedron. The lone pairs of tellurium, active, localised in the pseudo-rectangular tunnels are oriented parallel to Oy-axis between [Bi 2 Te 3 O 12 ] layers. r
Physical Review B, 2006
␣-Bi 2 O 3 is the thermodynamically stable phase of Bi 2 O 3 at room temperature. We have performed a theoretical and experimental investigation of its electronic structure using a combination of gradient corrected density functional theory ͑DFT͒, along with x-ray photoemission and O-K shell x-ray absorption and emission spectroscopies. We examine the nature of bonding in ␣-Bi 2 O 3 and in particular explore the nature of the stereochemically active Bi electron lone pair. The Bi 6s states are found to be concentrated at the bottom of the valence band but the states contributing to the lone pair on Bi are derived from the top of the valence band. Mixing between O 2p and Bi 6s states is found to be crucial in producing the asymmetric density on Bi. The role of the lone pair in the fast ion conductor ␦-Bi 2 O 3 is also investigated, through calculation of the electronic structure with ͗100͘, ͗110͘, and ͗111͘ alignment of oxygen vacancies. Alignment of the vacancies along ͗100͘ results in the most energetically favorable configuration of the ␦ phase, contrary to previous force field calculations and electrostatic arguments which favor the ͗111͘ alignment.