Bi Lone Pair Research Articles

Computational investigation of the Bi lone-pairs in monoclinic bismuth triborate BiB3O6

The Bi-O interactions and the Bi lone-pairs in monoclinic BiB3O6 are investigated with gradient-corrected hybrid B3PW density functional theory within the Gaussian-orbital-based CO-LCAO scheme. The Bi 6s and O 2p orbitals contribute to both bonding and antibonding interactions below the Fermi level. The stereochemical activity of the Bi lone-pairs was found to have a major origination from the primary interaction for the Bi 6s-O 2p antibonding orbital. The Bi 6p orbitals are not critically responsible for the non-spherical shape of the Bi lone-pairs, although they indeed participate into the secondary interaction with the Bi 6s-O 2p antibonding states. It is also suggested that O 2p components within the Bi lone-pairs are dominantly significant for the optical responses of BiB3O6 over the Bi 6s components.

Antiferroelectricity in multiferroic BiCrO3 epitaxial films

Multiferroic BiCrO3 epitaxial films were grown by pulsed laser deposition on SrTiO3 (001) substrates with SrRuO3 bottom electrodes. The authors found that the films exhibit antiferroelectricity with a characteristic electric field induced ferroelectric phase, as evidenced by double hysteretic behaviors in the electric field dependence of dielectric constants and polarization. The antiferroelectricity is consistent with theoretical predictions that the Bi lone pair induces polarization in bismuth-based perovskites, such as ferroelectric BiMnO3 and BiFeO3. Magnetic measurements revealed weak parasitic ferromagnetism resulting from antiferromagnetic ordering below 140K. This magnetic transition coincides with a local maximum in the dielectric constants’ temperature dependence.

Effect of 6 [formula omitted] lone pair of [formula omitted] on electrical transport properties of [formula omitted

Electrical transport and magnetic properties of Bi 3 + ion doped ( La 1 - x Bi x ) 0.67 Ca 0.33 MnO 3 ( 0 ⩽ x ⩽ 0.2 ) have been investigated. Experimental results show that the Bi 3 + dopant and its doping level x have an obvious effect on the electrical transport and magnetic properties of the ( La 1 - x Bi x ) 0.67 Ca 0.33 MnO 3 . Especially, in a higher Bi 3 + doping level of 0.05 < x < 0.2 , the effect resulting from Bi 3 + becomes significant. However, the experimental results cannot be interpreted only on the basis of the difference of ionic radius between La 3 + and Bi 3 + ions, it is necessary to consider the effects of the 6 s lone pair of Bi 3 + on the electrical transport process and magnetic domain rotation and growth behavior simultaneously.

Theoretical Prediction of New High-Performance Lead-Free Piezoelectrics

We predict the occurrence of large ferroelectric polarization and piezoelectricity in the hypothetical perovskite-structure oxides, bismuth aluminate (BiAlO 3 ) and bismuth gallate (BiGaO 3 ), using density functional theory within the local density approximation. We show that BiGaO 3 will have a similar structure to PbTiO 3 , although with much stronger tetragonal distortion and therefore improved ferroelectric properties. Likewise, BiAlO 3 shares structural characteristics with antiferrodistortive PbZrO 3 , but it is also a ferroelectric with large polarization. Therefore, we propose the Bi(Al,Ga)O 3 system as a replacement for the widely used piezoelectric material, Pb(Zr,Ti)O 3 (PZT), that will avoid the environmental toxicity problems of lead-based compounds. Finally, we show that, in both BiAlO 3 and BiGaO 3 , the large distortions from the prototypical cubic structure are driven by the stereochemical activity of the Bi lone pair.

New aluminate with a tetrahedral structure closely related to the c84 fullerene.

A new aluminate Sr33Bi(24+delta)Al48O(141+3delta/2), having an F3m cubic structure (a = 25.090 angstroms, Z = 4) and forming a close packed face centered cubic array of "Al84" fullerene geometry, has been discovered. This original structure consists of corner-sharing AlO4 tetrahedra forming "Al84O106" cubic units whose assemblage delimits five types of cages, three of them being empty, one being occupied by strontium, and the fifth one forming the huge spheric fullerene-type cavity. In the latter, strontium, oxygen, and bismuth ions form concentric spheres, with an onion-skin-like configuration. The latter ions are disposed into a compact "Bi16O(52-n[]n)" anion whose the exceptional geometry is characterized by a strong stereoactivity of the 6s2 lone pair of Bi3+.

Powder Neutron Diffraction and TEM Investigations of Bi 0.775Ln0.225O 1.5 Oxide Conductors ( Ln=La, Pr, Nd, Sm, Tb, Dy) with Rhombohedral Bi–Sr–O type: Structural Relationships with Monoclinic ε-Bi 4.86La 1.14O 9 Form

Structural investigations of Bi 0.775 Ln 0.225O 1.5 phases with rhombohedral Bi–Sr–O type, have been carried out using complementary techniques. Average crystal structures were refined from neutron diffraction powder data using the Rietveld method for Ln=La, Pr, Nd and Tb. The comparison with the monoclinic Bi 4.86La 1.14O 9 structure previously determined using the same technique has been done. For both types of structure, a piling of slabs constituted of a (Bi (1), Ln) oxide layer, inserted between two Bi (2) oxide layers, is observed. In the rhombohedral phases there are moreover oxide ions in the inter-slab spaces responsible for the well-known conductivity of these phases, while in the monoclinic Bi 4.86La 1.14O 9 structure, the absence of oxygen in the inter-slab spaces, is compensated with the presence of the Bi (2) lone pair electrons localized at a significant distance (≅1.20 Å), which participate in the cohesion of the crystal structure. TEM study of Bi 0.775 Ln 0.225O 1.5 samples, has confirmed the existence of superstructures for these phases and has allowed to propose two types (respectively for La and for Nd, Sm, Tb or Dy) of q 1 * and q 2 * modulation wave vectors.

Strong electronic consequences of intercalation in cuprate superconductors: the case of a trigonal planar AuI(3) complex stabilized in the Bi(2)Sr(2)CaCu(2)O(y) lattice.

Recently, a molecular AuI(3) complex was stabilized in the interlayer space of the Bi(2)Sr(2)CaCu(2)O(y) (Bi2212) high-T(c) superconducting phase, adopting an exceptional D(3)(h) structure (Choy, J.-H.; et al. J. Phys.Chem. B 2000, 104, 7273). If the gold were formally Au(III), a strong Jahn-Teller distortion to T- and Y-shaped structures would be expected. In this work, we try to understand the structural preferences of AuI(3) in both the gas phase and the Bi2212 lattice, as well as the influence of the AuI(3) intercalation on the superconductor lattice. What we think actually happens is that there is an effective electron transfer from the s-type Bi lone pair to the gold, increasing the formal oxidation state of Bi from +3 to +5 and decreasing that of Au from +3 to +1. A trigonal Au(I) trihalide is just fine. The DFT results confirm in the Bi-rich regions the same kind of electron transfer as encountered on the EHT level of theory, but they reveal additional complexities of the problem. The effect of the Bi to intercalating molecule electron transfer on the cuprate layer may be important, quite apart from this specific example, in tuning superconductivity in the cuprates.

Electronic and magnetic transitions in Bi–Sr–Mn–O oxides: high temperature charge-ordering

Neutron/synchrotron diffraction data and magnetic measurements provide direct evidence of charge/orbital ordering at anomalously high temperatures in (Bi,Sr)MnO 3 manganites. We report on the electronic and magnetic transitions of several oxides of this family. A mechanism based on the 6s 2 lone pair of Bi is proposed to strongly decrease the mobility of e g electrons and markedly favor charge-ordering.

Ab Initio Determination of Bi4.86La1.14O9 Monoclinic Structure from Powder Neutron Diffraction Data. Characterization of the Related Solid Solution

This paper deals with the ab initio determination of ϵ-Bi4.86La1.14O9 monoclinic structure from powder neutron data using the Rietveld method, and with physical properties characterization of a related solid solution. ϵ-Bi4.86La1.14O9, obtained from the annealing of a quenched rhombohedral high- temperature β1 sample, is monoclinic, P2/c, a=9.4956(3) Å, b=3.9742(1) Å, c=7.0425(2) Å, β=104.700(2)°; Z=1. The structure refinement converged to RF=0.043 and RBragg=0.047. The structure is built from cationic slabs parallel to (100) faces of the monoclinic cell. Each cell corresponds to one slab containing a mixed Bi0.86La1.14 cationic layer (Bi(1)) sandwiched between two equivalent bismuth layers (Bi(2)). The cohesion of the cations in the slabs results from the presence of the oxygen atoms distributed over three sites. Six O(1) and two O(2) atoms form a slightly distorted cubical polyhedron around the mixed cationic site (Bi(1)). Bi(2) atoms are surrounded by seven oxygen atoms in a very distorted polyhedron. The important delocalization of Bi(2) lone pairs toward the interslab spaces leads to significant bonds with the adjacent slabs and to the cohesion of the structure. ϵ-Bi4.86La1.14O9 is the low symmetry variety of a particular sample of a wide solid solution domain that, formulated Bi1−xLaxO1.5, has been investigated for 0.15≤x≤0.325. The formation of this phase from the irreversible transformation of quenched-β1 on heating and the subsequent transitions ϵ→β2→β1 have been evidenced by thermodiffractometry, conductivity measurements versus temperature, dilatometry, and thermal analyses. Thermal expansion coefficients (×105) are for a, c, and/or lattice volume for a quenched-β1, ϵ, β2 or β1 variety of Bi4.86La1.14O9 (x=0.19) respectively: 1.74, −0.72, 2.78; 5.25; 1.74, 1.81, 5.37; 0.99, 1.08, 3.90. The corresponding activation energies are 0.94, 0.83, 0.84, and 0.21 eV. The ϵ→β2 transition, irreversible for 0.15≤x≤0.275, appears partly reversible for 0.3≤x≤0.325.

Synthesis and characterization of (Bi, AE)MnO 3 (AE=Ca, Sr) system

The effects of electron lone pairs of trivalent bismuth ions on the crystal structure and magnetic properties were examined in Bi 1− x AE x MnO 3 (AE=Ca, Sr). Polycrystalline perovskite manganites Bi 1− x AE x MnO 3 were synthesized by using a conventional ceramic technique and a high-pressure technique (4 GPa). Perovskites with triclinic, monoclinic, and tetragonal distortions were found in Bi 1− x Sr x MnO 3 from X-ray powder diffraction. In particular superlattice reflections were found in BiMnO 3 by electron diffraction which revealed two kinds of unit cell, i.e. polymorphism. The bismuth lone pair character was reflected in these structures. Both Bi 1− x Ca x MnO 3 and La 1− x Ca x MnO 3 showed the same crystal symmetry and weak ferromagnetism in the Ca-rich region. However, the magnetic moment of Bi 1− x Ca x MnO 3 was larger than that of La 1− x Ca x MnO 3 with the same x value. Their ferromagnetism was suppressed by charge ordering with further substitution of trivalent cations, although the charge ordering temperature of the La-system is higher than that of the Bi system. The difference is probably associated with the Bi lone pair.

Bi12O14E12]nColumns and Lone PairsEin Bi13Mo4VO34E13: Synthesis, Crystal Structure, and Chemistry of the Bi2O3–MoO3–V2O5System

A new phase, Bi13Mo4VO34E13(E: Bi(III) lone pair) was found in the Bi2O3–MoO3–V2O5system and its formula determined via single crystal analysis and confirmed by solid state synthesis. It crystallizes in the monoclinic system, space groupP2/c, with cell parametersa=11.652(7)Å,b=5.7923(8)Å,c=24.420(9)Å,β=101.38(6)°, andZ=2. The crystal structure is built up by infinite [Bi12O14E12]ncolumns surrounded by 10 (Mo,V)O4tetrahedra, situated on layers parallel to (100) and (001), with an extra Bi atom located at the intersection of these “(Mo,V)O4layers” in between two tetrahedra. The Bi13Mo4VO34E13structure is in general agreement with that of R. N. Vannieret al.(1996,J. Solid State Chem.111, 118) giving a structural formulation Bi26M10O68but with their chemical formulations giving Bi26Mo10O69or Bi26Mo6V4O67and hypothetical nonstoichiometry Bi26M10Oδ. Taking into account the cell dimensions and structural details of Bi13Mo4VO34E13, which show that a reported phase like Bi6Mo2O15could also be isostructural, a new hypothesis based on the possible replacement of BiO4Etrigonal bipyramid and/or BiO3Etetrahedra for MoO4tetrahedra strengthens the probability that there is a continuous solid solution in the Bi2O3–MoO3system between the compositions 1.43 Bi2O3: 1 MoO3and 1.75 Bi2O3: 1 MoO3. Synthesis and cell dimensions of various compositions supporting these ideas are given. The domain of existence for such phases can extend in the pseudo-ternary Bi2O3–MoO3–V2O5system up to the phase Bi13Mo4VO34; this triangular area excludes Bi26Mo10O69and Bi26Mo6V4O67compositions.

Synthesis and Crystal Structure of the Alkylbismuth Diiodides: A Family of Extended One-Dimensional Organometallic Compounds

Crystals of the organometallic compounds CnH2n+1BiI2 (n = 2, 4) have been grown under solvothermal conditions, using a reaction between R3Bi (R = C2H5, C4H9) and BiI3, in a diethyl ether solution. Both compounds crystallize in the orthorhombic space group Pbam with the unit cell parameters a = 15.228(1) Å, b = 10.964(1) Å, c = 4.3505(2) Å, and Z = 4, for C2H5BiI2, and a = 25.515(2) Å, b = 8.4192(6) Å, c = 4.3467(2) Å, and Z = 4, for C4H9BiI2. The solid state structures of these two compounds, when compared with the recently reported CH3BiI2 (n = 1) structure, demonstrate that the alkylbismuth diiodides form a family of extended one-dimensional organic−inorganic materials. The framework of the RBiI2 (R = alkyl) chains in each compound is virtually identical, with each bismuth having a square pyramidal coordination of four iodines in the basal plane and a covalently bonded terminal carbon from an alkyl group in the apical site. Each basal square shares trans edges with two nearest neighbors to form a one-dimensional BiI2 chain, with the alkyl groups aligned on one side of the BiI2 basal plane. The Bi(III) lone pair is stereochemically active and extends into the space trans to each alkyl group. The principle difference between the members of this family derives from the stacking of the RBiI2 chains in the overall structure. This study demonstrates the flexibility to accommodate a range of different length organic constituents within a basic extended one-dimensional organometallic framework.

The 34 K superconductor Bi 2− xPb xSr 8Cu 4 (CO 3) 3O 12. A new oxycarbonate, third member of the series (Bi 2− xPb xSr 2CuO 6) (Sr 2CuO 2CO 3) n

A new superconducting bismuth oxycarbonate Bi 2− x Pb x Sr 8Cu 4(CO 3) 3O 12 has been synthesized for 0⩽x⩽0.25. This phase represents the n=3 member of the structural series (Bi 2− x Pb x Sr 2CuO 6) (Sr 2CuO 2CO 3) n , i.e. corresponds to an intergrowth of triple oxycarbonate layers with a single 2201 layer. Its structure, characterized by an orthorhombic subcell a≈ b≈ a p√ 2≈5.4 Å and c≈70 Å, is in fact modulated, as for all bismuth cuprates and oxycarbonates, in agreement with the stereoactivity of the 6s 2 lone pair of Bi(III). The critical temperature of this phase (34 K) is close to that of the lead-free first member (30 K) and smaller than that of the second member (40 K), but contrary to the two first members it is not increased by doping with lead.

Substitution of lead for bismuth in the 2201-type oxide Bi 2BaLaCuO 6+δ

The study of the substitution of bismuth in the 2201 bismuth barium cuprate allowed two isostructural phases Bi 2− x Pb x BaLaCuO 6+δ to be isolated for 0 ⩽ x ⩽ 1.40. The bismuth-rich phases (0 ⩽ x < 0.4) exhibit a modulated structure similar to that of B 2Sr 2CuO 6+δ, with a period along b ranging from 3.8 ( x = 0) to 4.2 ( x = 0.8). The lead-rich phases (0.8 ⩽ x ⩽ 1.4), do not exhibit any modulation of the structure, but are characterized by the existence of weak superstructure spots. The transition from the modulated to the non-modulated structure is accompanied by a dramatic increase of the c parameter of the orthorhombic oxides (5.4 × 5.4 × 24 Å 3). This evolution is interpreted in terms of the stereoactivity of the 6 s 2 lone pair of Bi(III) and Pb(II) and of the formation of anionic vacancies.

What about structure and nonstoichiometry in superconductive layered cuprates?

An overview of the structural relationships and classification of the superconductive layered cupratesis presented here. The problems of nonstoichiometry extended defects in thallium cuprates and oxygen nonstoichiometry in YBa 2Cu 3O 7− δ are discussed. The issue of incommensurability in a great number of those phases is studied in connection with the stereoactivity of the 6 s 2 lone pair of Bi(III), Pb(II), and Tl(I).

The crystal structure of di(5-amino-3-thione-1,2,4-dithiazole)tris-thiocyanatobismuthate(III), (C2H2N2S3)2Bi(SCN)3

Abstract Single crystals of (C2H2N2S3)2Bi(SCN)3 have been prepared from solution and its structure has been determined. (C2H2N2S3)2-Bi(SCN)3 is monoclinic, space grouip C2/c, a = 6.730(4), b = 13.285(4), c = 20.679(4) Å, β = 96.92(5)°, Z = 4. Four sites of the strongly distorted tetragonal antiprism forming the coordination polyhedron of the Bi atom are occupied by S and N atoms of two isoperthiocyanic acid molecules (isoperthiocyanic acid: 5-amino-3-thione-1,2,4-dithiazole). The C2N2S3 disubstituted five membered ring units of the isoperthiocyanic acid molecules are planar. The other four sites of the coordination polyhedron are occupied by S and N atoms of thiocyanate ions. Two of them form bonds via S to the Bi atom. A third thiocyanate group acts as a bidentate ligand, connecting neighbouring Bi atoms. These ambidently bridging thiocyanate ions are disordered, thus leading to infinite chains made up of equal numbers of – Bi – S – C – N – Bi′ – and – Bi – N – C – S – Bi′ – units, running nearly parallel to the crystallographic a-axis. The Bi – S distances range form 2.814(3) to 2.919(2) Å, the Bi – N distances are 2.695(6) Å for the binding N atom of the isoperthiocyanic acid molecule and 2.66(2) Å for the N atom of the disordered bridging thiocyanate ion, respectively. A possible location of the Bi(III) lone pair is briefly discussed.