Relevant bibliographies by topics / Octahedral structure

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Academic literature on the topic 'Octahedral structure'

Author: Grafiati
Published: 5 June 2025
Last updated: 24 June 2025

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Journal articles on the topic "Octahedral structure"

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Burns, Peter C. "The crystal structure of szenicsite, Cu3MoO4(OH)4." Mineralogical Magazine 62, no. 04 (1998): 461–69. http://dx.doi.org/10.1180/002646198547837.

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Abstract The crystal structure of szenicsite, Cu3MoO4(OH)4, orthorhombic, a = 8.5201(8), b = 12.545(1), c = 6.0794(6) Å, V = 649.8(2) Å3, space group Pnnm, Z = 4, has been solved by direct methods and refined by least-squares techniques to an agreement index (R) of 3.34% and a goodness-of-fit (S) of 1.11 for 686 unique observed [|F| ⩾ 4σF] reflections collected using graphite-monochromated Mo-Kα X-radiation and a CCD area detector. The structure contains three unique Cu2+ positions that are each coordinated by six anions in distorted octahedral arrangements; the distortions of the octahedra are due to the Jahn-Teller effect associated with a d 9 metal in an octahedral ligand-field. The single unique Mo6+ position is tetrahedrally coordinated by four O2− anions. The Cu2+ϕ6 (ϕ: unspecified ligand) octahedra share trans edges to form rutile-like chains, three of which join by the sharing of octahedral edges to form triple chains that are parallel to [001]. The MoO4 tetrahedra are linked to either side of the triple chain of Cu2+ϕ6 octahedra by the sharing of two vertices per tetrahedron, and the resulting chains are cross-linked through tetrahedral-octahedral vertex sharing to form a framework structure. The structure of szenicsite is closely related to that of antlerite, Cu3SO4(OH)4, which contains similar triple chains of edge-sharing Cu2+ϕ6 octahedra.
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Colombo, F., J. Rius, O. Vallcorba, and E. V. Pannunzio Miner. "The crystal structure of sarmientite, Fe23+ (AsO4)(SO4)(OH)·5H2O, solved ab initio from laboratory powder diffraction data." Mineralogical Magazine 78, no. 2 (2014): 347–60. http://dx.doi.org/10.1180/minmag.2014.078.2.08.

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AbstractThe crystal structure of sarmientite, Fe23+ (AsO4)(SO4)(OH)·5H2O, from the type locality (Santa Elena mine, San Juan Province, Argentina), was solved and refined from in-house powder diffraction data (CuKα1,2 radiation). It is monoclinic, space group P21/n, with unit-cell dimensions a = 6.5298(1), b = 18.5228(4), c = 9.6344(3) Å, β = 97.444(2)º, V = 1155.5(5) Å3, and Z = 4. The structure model was derived from cluster-based Patterson-function direct methods and refined by means of the Rietveld method to Rwp = 0.0733 (X2 = 2.20). The structure consists of pairs of octahedral-tetrahedral (Fe−As) chains at (y,z) = (0,0) and (½,½), running along a. There are two symmetry-independent octahedral Fe sites. The Fe1 octahedra share two corners with the neighbouring arsenate groups. Both individual chains are related by a symmetry centre and joined by two symmetry-related Fe2 octahedra. Each Fe2 octahedron shares three corners with double-chain polyhedra (O3, O4 with arsenate groups; the O8 hydroxyl group with the Fe1 octahedron) and one corner (O11) with the monodentate sulfate group. The coordination of the Fe2 octahedron is completed by two H2O molecules (O9 and O10). There is also a complex network of H bonds that connects polyhedra within and among chains. Raman and infrared spectra show that (SO4)2− tetrahedra are strongly distorted.
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Schwendtner, Karolina, and Uwe Kolitsch. "Octahedral As in M + arsenates – architecture and seven new members." Acta Crystallographica Section B Structural Science 63, no. 2 (2007): 205–15. http://dx.doi.org/10.1107/s0108768106054942.

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Arsenates with arsenic in octahedral coordination are very rare. The present paper provides an overview of all known M + arsenates(V) containing octahedrally coordinated arsenic (M + = Li, Na, K, Rb, Cs, Ag) and the crystal structures (determined from single-crystal X-ray diffraction data) of the following seven new hydrothermally synthesized members belonging to six different structure types, four of which are novel: LiH2As3O9, LiH3As2O7, NaHAs2O6-type KHAs2O6, KH3As4O12 and isotypic RbH3As4O12, CsAs3O8 and NaH2As3O9-type AgH2As3O9. The main building unit of these compounds is usually an As4O14 cluster of two edge-sharing AsO6 octahedra sharing two apical corners each with two AsO4 tetrahedra. The different connectivity between these clusters defines the different structure types. The novel CsAs3O8 structure, based on a derivative of the As4O14 cluster, is the most condensed of all these M + arsenates, with an O/As ratio of only 2.67 compared with values of 2.75–3.5 for the remaining members. This is achieved through polymerization of the cluster derivatives to infinite chains of edge-sharing AsO6 octahedra. The [4]As/[6]As ratio drops to only 0.5. All but two of the protonated title compounds show protonated AsO6 octahedra. Hydrogen bonds range from very strong to weak. An analysis of bond-length distribution and average bond lengths in AsO6 octahedra in inorganic compounds leads to an overall mean As—O distance for all known AsO6 octahedra (with R factors < 0.072) of 1.830 (2) Å.
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Balić-Žunić, Tonči, Martha G. Pamato, and Fabrizio Nestola. "Redetermination and new description of the crystal structure of vanthoffite, Na6Mg(SO4)4." Acta Crystallographica Section E Crystallographic Communications 76, no. 6 (2020): 785–89. http://dx.doi.org/10.1107/s2056989020005873.

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The crystal structure of vanthoffite {hexasodium magnesium tetrakis[sulfate(VI)]}, Na6Mg(SO4)4, was solved in the year 1964 on a synthetic sample [Fischer & Hellner (1964). Acta Cryst. 17, 1613]. Here we report a redetermination of its crystal structure on a mineral sample with improved precision. It was refined in the space group P21/c from a crystal originating from Surtsey, Iceland. The unique Mg (site symmetry \overline{1}) and the two S atoms are in usual, only slightly distorted octahedral and tetrahedral coordinations, respectively. The three independent Na atoms are in a distorted octahedral coordination (1×) and distorted 7-coordinations intermediate between a `split octahedron' and a pentagonal bipyramid (2×). [MgO6] coordination polyhedra interchange with one half of the sulfate tetrahedra in <011> chains forming a (100) meshed layer, with dimers formed by edge-sharing [NaO7] polyhedra filling the interchain spaces. The other [NaO7] polyhedra are organized in a parallel layer formed by [010] and [001] chains united through edge sharing and bonds to the remaining half of sulfate groups and to [NaO6] octahedra. The two types of layers interconnect through tight bonding, which explains the lack of morphological characteristics typical of layered structures.
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Beck, J., and F. Wolf. "Three New Polymorphic Forms of Molybdenum Pentachloride." Acta Crystallographica Section B Structural Science 53, no. 6 (1997): 895–903. http://dx.doi.org/10.1107/s0108768197008331.

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Three new polymorphic modifications of molybdenum pentachloride could be obtained by solvothermal syntheses in CCl4 and SbCl5 as solvents. The structures have been solved by single-crystal X-ray diffraction. The already known structure of monoclinic \alpha-MoCl5 (C2/m) is not isomorphous with \alpha-NbCl5 and is better derived from the closest packing of Cl atoms of the Sm type with molybdenum occupying 1/5 of the octahedral holes. The triclinic structure of \beta-MoCl5 (P\overline 1) can be derived from hexagonal closest packing. The orthorhombic structure of \gamma-MoCl5 (Pnma) and the monoclinic structure of \delta-MoCl5 (P21/c) can both be derived from double-hexagonal closest packing. All four forms of MoCl5 have in common the discrete Mo2Cl10 moieties built from edge-sharing double octahedra with the metal atoms displaced from the octahedron centres away from each other. The differences between the modifications lie in the different stacking sequences of the close-packed Cl-atom layers and the different occupation of the octahedral interstices. This is reflected in the group–subgroup relationships of the space groups of the closest packings and the molybdenum pentachlorides. X-ray powder diffraction shows that sublimed MoCl5 is a mixture of all four modifications in variable amounts and probably a further unknown form.
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Martin, C. David, Yue Meng, Vitali Prakapenka, and John B. Parise. "Gasketing optimized for large sample volume in the diamond anvil cell: first application to MgGeO3and implications for structural systematics of the perovskite to post-perovskite transition." Journal of Applied Crystallography 41, no. 1 (2008): 38–43. http://dx.doi.org/10.1107/s0021889807050029.

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Structure models of MgGeO3post-perovskite (Cmcm) are presented, along with a structure survey, demonstrating that all perovskite, post-perovskite and CaIrO3-type structures (ABX3) have specific ranges of the volume ratio between cation-centered polyhedra (VA:VB). The quality of the reported diffraction data and MgGeO3structure models is enhancedviaimplementation of a new graphite gasket for the diamond anvil cell, which stabilizes a larger sample volume, improving powder statistics during X-ray diffraction, andviathe thermal insulation required to achieve ultra-high temperatures while laser-heating samples at pressures near 100 GPa. The structure survey supports the theory that the pressure–temperature conditions under which the perovskite/post-perovskite phase transition occurs can be estimated by extrapolating the change inVA:VBto a value of 4, which corresponds to a maximum tilt ofBX6octahedra in the perovskite structure (Pbnm) where inter-octahedral anion–anion distances match the average intra-octahedral anion–anion distance. Once these short inter-octahedral distances between anions are reached in the perovskite structure, further tilting of octahedra and decrease of theVA:VBratio does not occur, driving the transition to post-perovskite structure as pressure is increased.
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Post, Jeffrey E., Peter J. Heaney, and Andreas Ertl. "Rietveld refinement of the ranciéite structure using synchrotron powder diffraction data." Powder Diffraction 23, no. 1 (2008): 10–14. http://dx.doi.org/10.1154/1.2836477.

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Rietveld refinement using synchrotron powder X-ray diffraction data of the ranciéite, Ca0.19K0.01(Mn4+0.91◻0.09)O2⋅0.63H2O, crystal structure reveals significant differences from that reported previously. The interlayer H2O molecules occupy sites halfway between the Mn,O octahedral sheets. The Mn sites in the octahedral sheets have 10% vacancies, and the mean Mn–O distance indicates that all Mn is tetravalent (Mn4+). The interlayer Ca cations are located above and below the Mn vacancies and are octahedrally coordinated to three O2 atoms in the octahedral sheet and three H2O molecules in the interlayer.
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Kovac, Sabina, Predrag Dabic, and Aleksandar Kremenovic. "Crystal structure of K3EuSi2O7." Journal of the Serbian Chemical Society 86, no. 7-8 (2021): 663–72. http://dx.doi.org/10.2298/jsc210218026k.

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As part of research on the flux technique for growing alkali rare-earth elements (REE) containing silicates, tripotassium europium disilicate, K3EuSi2O7, was synthesized and characterized by single-crystal X-ray diffraction. It crystallizes in the space group P63/mcm. In the crystal structure of the title compound, one part of the Eu cations are in a slightly distorted octahedral coordination and the other part are in an ideal trigonal prismatic coordination environment. The disilicate Si2O7 groups connect four EuO6 octahedra and one EuO6 trigonal prism. Three differently coordinated potassium cations are located between them. Silicates containing the larger rare earth elements usually crystallize in a structure that contains the rare-earth cation in both a slightly distorted octahedral and an ideal trigonal prismatic coordination environment.
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Redhammer, Günther J., Haruo Ohashi, and Georg Roth. "Single-crystal structure refinement of NaTiSi2O6 clinopyroxene at low temperatures (298 < T < 100 K)." Acta Crystallographica Section B Structural Science 59, no. 6 (2003): 730–46. http://dx.doi.org/10.1107/s0108768103022018.

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The alkali-metal clinopyroxene NaTi3+Si2O6, one of the rare compounds with trivalent titanium, was synthesized at high temperature/high pressure and subsequently investigated by single-crystal X-ray diffraction methods between 298 and 100 K. One main difference between the high- and the low-temperature form is the sudden appearance of two different Ti3+—Ti3+ interatomic distances within the infinite chain of the TiO6 octahedra just below 197 K. This change can be seen as direct evidence for the formation of Ti—Ti singlet pairs in the low-temperature phase. Mean Ti—O bond lengths smoothly decrease with decreasing temperature and the phase transition is associated with a slight jump in the Ti—O bond length. The break in symmetry, however, causes distinct variations, especially with respect to the two Ti—Oapex bond lengths, but also with respect to the four Ti—O bonds in the equatorial plane of the octahedron. The TiO6 octahedron appears to be stretched in the chain direction with a slightly larger elongation in the P\bar 1 low-temperature phase compared with the C2/c high-temperature phase. Polyhedral distortion parameters such as bond-length distortion and octahedral angle variance suggest the TiO6 octahedron in P\bar 1 to be closer to the geometry of an ideal octahedron than in C2/c. Mean Na—O bond lengths decrease with decreasing temperature and the variations in individual Na—O bond lengths are the result of variations in the geometry of the octahedral site. The tetrahedral site acts as a rigid unit, which does not show pronounced changes upon cooling and through the phase transitions. There are neither large changes in bond lengths and angles nor in polyhedral distortion parameters, for the tetrahedral site, when they are plotted. In contrast with the C2/c → P21/c phase transition, found especially in LiMSi2O6 clinopyroxenes, no very large variations are found for the tetrahedral bridging angle. Thus, it is concluded that the main factor inducing the phase transition and controlling the structural variations is the M1 octahedral site.
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Reinauer, F., and R. Glaum. "Ideal and Real Structure of Ti5O4(PO4)4: X-ray and HRTEM Investigations." Acta Crystallographica Section B Structural Science 54, no. 6 (1998): 722–31. http://dx.doi.org/10.1107/s0108768198003590.

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The crystal structure of pentatitanium tetraoxide tetrakis(phosphate), Ti5O4(PO4)4, has been determined and refined from X-ray diffraction single-crystal data [P212121 (No. 19), Z = 4, a = 12.8417 (12), b = 14.4195 (13), c = 7.4622 (9) Å (from Guinier photographs); conventional residual R 1 = 0.042 for 2556 Fo &gt; 4σ(Fo ), R 1 = 0.057 for all 3276 independent reflections; 282 parameters; 29 atoms in the asymmetric unit of the ideal structure]. The structure is closely related to those of β-Fe2O(PO4)-type phosphates and synthetic lipscombite, Fe3(PO4)4(OH). While these consist of infinite chains of face-sharing MO6 octahedra, in pentatitanium tetraoxide tetrakis(phosphate) only five-eighths of the octahedral voids are occupied according to □3Ti5O4(PO4)4. Four of the five independent Ti4+O6 show high radial distortion [1.72 ≤ d(Ti−O) ≤ 2.39 Å] and a typical 1 + 4 + 1 distance distribution. The fifth Ti4+O6 is an almost regular octahedron [1.91 ≤ d(Ti−O) ≤ 1.98 Å]. Partial disorder of Ti4+ over the available octahedral voids is revealed by the X-ray structure refinement. High-resolution transmission electron microscopy (HRTEM) investigations confirm this result.
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Dissertations / Theses on the topic "Octahedral structure"

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Eng, Hank W. "The crystal and electronic structures of oxides containing d0 transition metals in octahedral coordination." Connect to this title online, 2003. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1070570079.

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Thesis (Ph. D.)--Ohio State University, 2003.<br>Title from first page of PDF file. Document formatted into pages; contains xx, 180 p.; also includes graphics. Includes bibliographical references (p. 139-145).
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Sreekantan, Nair Lalithambika Sreeju [Verfasser]. "Electronic Structure of Cobalt Octahedral Complexes in Aqueous Solution / Sreeju Sreekantan Nair Lalithambika." Berlin : Freie Universität Berlin, 2019. http://d-nb.info/1190087898/34.

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Matsui, Tsuneo, Takanori Nagasaki, Shunsuke Muto, et al. "Thermoelectric properties of Ba3Co2O6(CO3)0.7 containing one-dimensional CoO6 octahedral columns." AIP, 2009. http://hdl.handle.net/2237/20785.

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Knapp, Meghan C. "Investigations into the structure and properties of ordered perovskites, layered perovskites, and defect pyrochlores." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1149097068.

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Schumer, Benjamin N., Marcelo B. Andrade, Stanley H. Evans, and Robert T. Downs. "A new formula and crystal structure for nickelskutterudite, (Ni,Co,Fe)As-3, and occupancy of the icosahedral cation site in the skutterudite group." MINERALOGICAL SOC AMER, 2017. http://hdl.handle.net/10150/623060.

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We propose a new formula for the mineral nickelskutterudite, based on our observation that either (or both) Co or Fe3+ are essential structure constituents. The crystal structure of nickelskutterudite, (Ni,Co,Fe) As-3, cubic, Im (3) over bar, Z = 8: a = 8.2653(6) angstrom, V = 564.65(7) angstrom, has been refined to R-1 = 1.4% for 225 unique reflections I > 2 sigma(1) collected on a Bruker X8 four-circle diffractometer equipped with fine-focus, sealed tube MoKa radiation and an APEX-II CCD detector. This is the first report of the crystal structure of nickelskutterudite. Nickelskutterudite, a member of the skutterudite group of isostructural minerals, adopts a distorted perovskite structure with notably tilted octahedra and an unoccupied to partially occupied icosahedral metal site. In the structure of nickelskutterudite, there is one metal (B) site occupied by Ni, Co, or Fe in octahedral coordination with six As atoms. Procrystal electron density analysis shows each As anion is bonded to two cations and two As anions, resulting in a four-membered ring of bonded As with edges 2.547 and 2.475 angstrom. The extreme tilting of BAs6 octahedra is likely a consequence of the As-As bonding. The nickelskutterudite structure differs from the ideal perovskite structure (A(4)B(4)X(12)) in that As4 anion rings occupy three of the four icosahedral cages centered on the A sites. There are reported synthetic phases isomorphous with skutterudite with the other A site completely occupied by a cation (AB(4)X(12)). Electron microprobe analyses of nickelskutterudite gave an empirical chemical formula of (Ni0.62Co0.28Fe0.12)(Sigma 1.02)(AS(2.95)S(0.05))(Sigma 3.00) normalized to three anions. Pure NiAs3 nickelskutterudite, natural or synthesized, has not been reported. In nature, nickelskutterudite is always observed with significant Co and Fe, reportedly because all non-bonded valence electrons must be spin-paired. This suggests that nickelskutterudite must contain Co3+ and Fe2+, consistent with previous models since Ni4+ cannot spin-pair its seven non-bonded electrons, Co3+ and Fe2+, which can spin-pair all non-bonded electrons, are required to stabilize the structure. No anion deficiencies were found in the course of this study so, including the structurally necessary Co and Fe, the chemical formula of nickelskutterudite (currently given as NiAs3-x, by the IMA) should be considered (Ni,Co,Fe)As-3.
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Yoshida, Suguru. "Structure-Property Correlations in Complex Oxides with Broken Inversion Symmetry." Kyoto University, 2020. http://hdl.handle.net/2433/253287.

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Yaguchi, Momo. "The Effect of Lattice Strain in Electrochemical Oxidations Catalyzed by Au-PdPt Core-shell Octahedral Nanoparticles." Thesis, Boston College, 2012. http://hdl.handle.net/2345/2928.

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Thesis advisor: Chia-kuang Frank Tsung<br>Pt-based alloy and core-shell nanoparticles have been intensively studied to regulate its size and shape. It has known that these nanoparticles show enhanced catalytic activity in various important fields such as heterogeneous catalysis, and electrochemical energy storage including fuel cells and metal-air batteries. Here, we report a facile hydrothermal synthesis of sub-10 nm PdPt alloy and sub-20 nm Au@PdPt core-shell structures. By using a mild reducing agent in aqueous solution, metal precursors are co-reduced. Specific gases are introduced during the synthesis to optimize the reaction conditions. The PdPt alloy and Au@PdPt core-shell nanostructures were characterized and confirmed by TEM, HRTEM, EDS, ICP-OES and XRD. The resulting PdPt and Au@PdPt particles are monodispersed single crystalline and octahedral shape enclosed by (111) facets. The electrocatalytic activity for the oxidation of formic acid was tested. It was found that the catalytic activity toward the formic acid oxidation of Au@PdPt core-shell particles were much higher than those of PdPt alloy particles. In addition, Pt-rich compositions were the most active in both PdPt alloy and Au@PdPt core-shell nanoparticles. Further studies on thinner alloy-shell core-shell nanoparticles reveal that there is a volcano-curve relationship between the lattice strain strength related to alloy-shell thickness and the catalytic performance. It is proposed that there are three key parameters that can determine the catalytic activity: the alloy composition, the presence of the gold core, and the thickness of alloy-shell<br>Thesis (MS) — Boston College, 2012<br>Submitted to: Boston College. Graduate School of Arts and Sciences<br>Discipline: Chemistry
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Kavanagh, Christopher M. "Synthesis and structure-property relationships in rare earth doped bismuth ferrite." Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/3555.

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There has been significant interest in BiFeO₃ over the past decade. This interest has focused on the magnetic and electrical properties, which in the long term may prove useful in device applications. This thesis focuses on the synthesis, electrical characterisation, and structural origin of the electrical properties of rare earth doped bismuth ferrite. Two systems have been studied: BiFeO₃ doped with lanthanum and neodymium (Bi₁₋ₓREₓFeO₃ RE= La, Nd). Specific examples have been highlighted focusing on a detailed structural analysis of a lanthanum doped bismuth ferrite, Bi₀.₅La₀.₅FeO₃, and a neodymium analogue, Bi₀.₇Nd₀.₃FeO₃. Both adopt an orthorhombic GdFeO₃-type structure (space group: Pnma) with G-type antiferromagnetism. Structural variations were investigated by Rietveld refinement of temperature dependent powder neutron diffraction using a combination of both conventional “bond angle/bond length” and symmetry-mode analysis. The latter was particularly useful as it allowed the effects of A-site displacements and octahedral tilts/distortions to be considered separately. This in-depth structural analysis was complemented with ac-immittance spectroscopy using the multi-formulism approach of combined impedance and modulus data to correlate structural changes with the bulk electrical properties. This approach was essential due to the complex nature of the electrical response with contributions from different electroactive regions. The structural variations occur due to a changing balance between magnetic properties and other bonding contributions in the respective systems. This results in changes in the magnitude of the octahedral tilts, and A-site displacements giving rise to phenomena such as negative thermal expansion and invariant lattice parameters i.e., the invar effect. More specifically, analysis of Bi₀.₅La₀.₅FeO₃ highlights a structural link between changes in the relative dielectric permittivity and changes in the FeO₆ octahedral tilt magnitudes, accompanied by a structural distortion of the octahedra with corresponding A-site displacement along the c-axis; this behaviour is unusual due to an increasing in-phase tilt mode with increasing temperature. The anomalous orthorhombic distortion is driven by magnetostriction at the onset of antiferromagnetic ordering resulting in an Invar effect along the magnetic c-axis and anisotropic displacement of the A-site Bi³⁺ and La³⁺ along the a-axis. This contrasts with the neodymium analogue Bi₀.₇Nd₀.₃FeO₃ in which a combination of increasing A-site displacements in the ac-plane and decrease in both in-phase and anti-phase tilts combine with superexchange giving rise to negative thermal expansion at low temperature. The A-site displacements correlate with the orthorhombic strain. By carefully changing the synthesis conditions, a significant change in bulk conductivity was observed for a number for Bi₁₋ₓLaₓFeO₃ compositions. A series of Bi₀.₆La0.₄FeO₃ samples are discussed, where changes in the second step of the synthesis result in significantly different bulk conductivities. This behaviour is also observed in other compositions e.g. Bi₀.₇₅La₀.₂₅FeO₃. Changes in the electrical behaviour as a function of temperature are discussed in terms of phase composition and concentration gradients of defects. Activation energies associated with the conduction process(es) in Bi₁₋ₓLaₓFeO₃ samples, regardless of composition, fall within one of two broad regimes, circa. 0.5 eV or 1.0 eV, associated with polaron hopping or migration of charge via oxygen vacancies, respectively. The use of symmetry-mode analysis, in combination with conventional crystallographic analysis and electrical analysis using multi-formulism approach, presents a new paradigm for investigation of structure-property relationships in rare earth doped BiFeO₃.
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Jackson, Lee. "Some structural and physical properties of two-dimensional antiferromagnets and other octahedral structures." Thesis, University of Essex, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386095.

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Vaidya, Rohan. "Optimum Support Structure Generation for Additive Manufacturing using Unit Cell Structures and Support Removal Constraint." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1490354059543447.

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Books on the topic "Octahedral structure"

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Lalvani, Haresh. Transformational part-count in layered octahedral-tetrahedral truss configurations. National Aeronautics and Space Administration, Langley Research Center, 1990.

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Lalvani, Haresh. Transformational part-count in layered octahedral-tetrahedral truss configurations. National Aeronautics and Space Administration, Langley Research Center, 1990.

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Center, Langley Research, ed. Transformational part-count in layered octahedral-tetrahedral truss configurations. National Aeronautics and Space Administration, Langley Research Center, 1990.

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Lalvani, Haresh. Comparative morphology of configurations with reduced part count derived from the octahedral-tetrahedral truss. National Aeronautics and Space Administration, Langley Research Center, 1991.

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Book chapters on the topic "Octahedral structure"

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Fedorov, Vladimir E., and Nikolay G. Naumov. "Octahedral Chalcogenide Rhenium Clusters: From Solids to Isolated Cluster Complexes." In Structure and Bonding. Springer International Publishing, 2019. http://dx.doi.org/10.1007/430_2019_33.

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Nolet, Marie-Christine, Rémi Beaulac, Anne-Marie Boulanger, and Christian Reber. "Allowed and Forbidden d-d Bands in Octahedral Coordination Compounds: Intensity Borrowing and Interference Dips in Absorption Spectra." In Structure and Bonding. Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/b96901.

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Lemoine, Pierric, Jean-François Halet, and Stéphane Cordier. "Inorganic Niobium and Tantalum Octahedral Cluster Halide Compounds with Three-Dimensional Frameworks: A Review on Their Crystallographic and Electronic Structures." In Structure and Bonding. Springer International Publishing, 2019. http://dx.doi.org/10.1007/430_2019_39.

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Bárány, Imre. "Tensors, colours, octahedra." In Geometry, Structure and Randomness in Combinatorics. Scuola Normale Superiore, 2014. http://dx.doi.org/10.1007/978-88-7642-525-7_1.

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Greenblatt, M., and B. Raveau. "Oxides with Intercalation Structures: Layers Built up of Edqe-Sharing Octahedra." In Inorganic Reactions and Methods. John Wiley & Sons, Inc., 2007. http://dx.doi.org/10.1002/9780470145203.ch133.

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Yu, Xiao Long, Shu Xiang Wu, Xia Yan Qiu, Ya Jing Liu, and Shu Wei Li. "Electron Transport Property and Pressure Effects in Au1-xTixO3 Octahedral Potential." In Advances in Composite Materials and Structures. Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-427-8.953.

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Mochiku, T., M. Nakahara, E. Abe, et al. "Crystal Structure of Sr1.9Nd1.1Cu2.1Nb0.9O8 and Sr2(Nd0.75Ce0.25)2Cu2NbO10: Ba2YCu3O6+δ-Related Compounds with NbO6 Octahedron." In Advances in Superconductivity X. Springer Japan, 1998. http://dx.doi.org/10.1007/978-4-431-66879-4_79.

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Kumari, Neeraj, and Chandra Mohan. "Basics of Clay Minerals and Their Characteristic Properties." In Clay and Clay Minerals [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.97672.

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Clay minerals such as kaolinite, smectite, chlorite, micas are main components of raw materials of clay and formed in presence of water. A large number of clays used to form the different structure which completely depends on their mining source. They are known as hydrous phyllosilicate having silica, alumina and water with variable amount of inorganic ions like Mg2+, Na+, Ca2+ which are found either in interlayer space or on the planetary surface. Clay minerals are described by presence of two-dimensional sheets, tetrahedral (SiO4) and octahedral (Al2O3). There are different clay minerals which are categorized based on presence of tetrahedral and octahedral layer in their structure like kaolinite (1:1 of tetrahedral and octahedral layers), smectite group of clay minerals (2:1 of tetrahedral and octahedral layers) and chlorite (2:1:1 of tetrahedral, octahedral and octahedral layers). The particle size of clay minerals is &lt;2microns which can be present in form of plastic in presence of water and solidified when dried. The small size and their distinctive crystal structure make clay minerals very special with their unique properties including high cation exchange capacity, swelling behavior, specific surface area, adsorption capacity, etc. which are described in this chapter. Due to all these unique properties, clay minerals are gaining interest in different fields.
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Müller, Ulrich, and Gemma de la Flor. "Derivation of crystal structures from closest packings of spheres." In Symmetry Relationships between Crystal Structures, 2nd ed. Oxford University PressOxford, 2024. https://doi.org/10.1093/oso/9780192858320.003.0014.

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Abstract A large number of crystal structures can be derived by partial occupation of interstices in closest packings of spheres. Examples are the rhombohedral, hexagonal and trigonal hettotypes that result from the partial occupation of octahedral voids in the hexagonal-closest packing of spheres. Other examplers are the hettotypes of the NaCl structure with a doubled unit cell and partial occupation of the octahedral voids, and the hetttotypes of the CaF2 type with a doubled unit cell and partial occupation of the tetrahedral voids.
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Aslan, Mikail, and Cengiz Bozada. "The Rare-Earth Hexaborides." In Rare-Earth Metal Hexaborides: Synthesis, Properties, and Applications. BENTHAM SCIENCE PUBLISHERS, 2023. http://dx.doi.org/10.2174/9789815124576123010004.

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Rare-earth hexaborides (REB6 ) are composed of rare-earth elements and octahedral 3D boron units. In Chapter 1, rare-earth elements were examined in detail; in this part, the REB6 will be explained. Hence, rare-earth hexaborides (REB6 ) consisting of rare-earth elements and octahedral bor units are a group of ceramic materials that have a simple cubic structure with Pm3m symmetry. Their low electronic work function, low electrical resistance, and thermal expansion coefficient (in some temperature ranges), as well as high hardness and stiffness, high chemical and thermal stability, and melting points, provide a wide range of industrial uses from metallurgy to electronics.
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Conference papers on the topic "Octahedral structure"

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Mitsunaga, Haruho, and Akio Noda. "Space-Filling Truncated Octahedron Climbing Modular Robots for the Construction of High-Rise Structures on the Lunar Surface." In 2025 IEEE/SICE International Symposium on System Integration (SII). IEEE, 2025. https://doi.org/10.1109/sii59315.2025.10871011.

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Calise, Gian J., and Anil Saigal. "Anisotropy and Failure in Octahedral Lattice Structure Parts Fabricated Using the FDM Technology." In ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-70904.

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Mechanical metamaterials are man-made materials in which the mechanical properties are mainly defined by their structures instead of the properties of each component. Periodic cellular structures consisting of honeycomb, tetrahedral, 3D Kagome and pyramidal truss arrangement of webs or struts have recently attracted a lot of attention since they have a broad range of applications including structural components, energy absorption, heat exchangers, catalyst support, filters and biomaterials. In addition, lattice structures such as the octahedral are being investigated since they are structurally more efficient than foams of a similar density made from the same material, and the ease with which these structures can now be produced using 3D printing and additive manufacturing. This research investigates the mechanical behavior and anisotropy in octahedral lattice structures of two different relative densities fabricated out of Acrylonitrile butadiene styrene (ABS) using Stratasys FDM 360mc and Dimension sst 1200es 3D printers. The machines were used to print octahedral lattice structured parts with struts 1.00 mm in diameter followed by parts with struts 2.6 mm in diameter and tested in compression in three mutually perpendicular directions. The compressive stress-strain behavior of the lattice structures observed is typical of cellular structures which include a region of nominally elastic response, yielding, and plastic strain hardening to a peak in strength, followed by a drop in flow stress. It was found that not only is the stiffness and strength of the as fabricated parts anisotropic but they, in addition to failure, are also a function of the relative density/strut diameter of the structure.
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Tran Thuy, Tuyet Mai, and Dung Van Nguyen. "Octahedral Molecular Sieve Manganese Oxide: Feasible Material for Hg(II) Remediation." In 5th International Conference on Advanced Materials Science. Trans Tech Publications Ltd, 2023. http://dx.doi.org/10.4028/p-03m8d0.

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Manganese-oxide material prepared by simple sol-gel method was used as an adsorbent of Hg(II) in aqueous solution. X-ray diffraction pattern and Raman spectroscopy were conducted to prove the cryptomelane crystal. The Hg(II) adsorption behavior of the synthesized material well obeyed kinetic models of pseudo-second-order and Elovich equations indicating a chemisorption from the collected kinetic parameters. 500 mgHg2+/gcryptomelane of equilibrium uptake capacity from pseudo-second-order and 7.87x103 mgHg2+/gcryptomelane/day of initial adsorption rate from the Elovich model were obtained for adsorption of Hg2+ cation over cryptomelane adsorbent. Desorption constant of 0.018 gcryptomelane/mgHg is a significant small value, in comparison to initial adsorption rate, proposing a possible chemisorption for remediation of Hg(II) on cryptomelane structure.
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Moe, Kyaw Soe, and Paul Johnson. "CUBO-OCTAHEDRAL GROWTH STRUCTURE IN A TYPE IB DOMINANT MIXED TYPE DIAMOND: A RARE DIAMOND FORMATION." In GSA Annual Meeting in Indianapolis, Indiana, USA - 2018. Geological Society of America, 2018. http://dx.doi.org/10.1130/abs/2018am-322707.

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Ueki, Takemi, Manabu Itsumi, and Tadao Takeda. "Octahedral Void Structure Observed at the Grown-In Defects in the Bulk of Standard CZ-Si for MOSLSIs." In 1996 International Conference on Solid State Devices and Materials. The Japan Society of Applied Physics, 1996. http://dx.doi.org/10.7567/ssdm.1996.la-1.

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Mosses, R. W., J. P. R. Wells, T. P. J. Han, H. G. Gallagher, and M. Yamaga. "Spectroscopy of Rare-Earth Doped Perovskite Phase Strontium Lanthanum Aluminate." In The European Conference on Lasers and Electro-Optics. Optica Publishing Group, 1998. http://dx.doi.org/10.1364/cleo_europe.1998.cthh47.

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Strontium lanthanum aluminate (SrLaAlO4) belongs to a wide family of compounds with the general formula ABCO4 (where A denotes an alkaline earth cation: B denotes Y. Sc or a trivalent rare earth element and C denotes Al, Ga or a transition metal ion). This material crystallises in the perovskite phase, with tetragonal K2NiF4 structure having space group 14/mmm. The structure is composed of CO6 layers in the ab plane. The C cations are surrounded by six oxygens and sit in slightly distorted octahedral sites. Between these layers, the A cations and trivalent B cations are randomly distributed in nine co-ordinated sites of C4v symmetry. The random distribution of Sr2+ and La3+ ions leads to a structural disorder that causes inhomogeneous broadening of the spectral lines of rare-earth ions doped into these crystals.
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Robertson, M. G., J. Haseltine, and S. Tawfick. "Inflatable Octet-Truss Structures." In ASME 2016 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/smasis2016-9090.

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The development of variable-stiffness systems is key to the advance of compact engineering solutions in a number of fields. Rigidizable structures exhibit variable-stiffness based on external stimuli. This function is necessary for deployable structures, such as inflatable space antennas, where the deployed structure is semi-permanent. Rigidization is also useful for a wide range of applications, such as prosthetics and exoskeletons, to help support external loads. In general, variable-stiffness designs suffer from a tradeoff between the magnitude of stiffness change and the ability of the structure to resist mechanical failure at any stiffness state. This paper presents the design, analysis, and fabrication of a rigidizable structure based on inflatable octet-truss cells. An octet-truss is a lattice-like configuration of elements, traditionally beams, arranged in a geometry reminiscent of that of the FCC lattice found in many metals; namely, the truss elements are arranged to form a single interior octahedral cell surrounded by eight tetrahedral cells. The interior octahedral cell is the core of the octet-truss unit cell, and is used as the main structure for examining the mechanics of the unit as a whole. In this work, the elements of the inflatable octet truss are pneumatic air muscles, also called McKibben actuators. Generalized McKibben actuators are a type of tubular pneumatic actuator that possess the ability to either contract or expand axially due to an applied pressure. Their unique kinematics are achieved by using a fiber wrap around an isotropic elastomeric shell. Under normal conditions, pressurizing the isotropic shell causes expansion in all directions, like a balloon. The fiber wrap constrains the ability of the shell to freely expand, due to the fiber stiffness. The wrap geometry thus guides the extensile/contractile motion of the actuator by controlling its kinematics. It is their ability to contract under pressure that makes McKibben actuators unique, and consequently they are of great interest presently to the robotics community due to their similitude to organic muscles. Kinematic analysis from constrained maximization of the shell volume during pressurization is used to obtain relations between the input work due to applied pressure and the resulting shape change due to strain energy. Analytical results are presented to describe the truss stiffness as a function of the McKibben geometry at varying pressures.
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Saigal, Anil, John R. Tumbleston, and Hendric Vogel. "Mechanical Response of Different Lattice Structures Fabricated Using the CLIP Technology." In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-65907.

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In the rapidly growing field of additive manufacturing (AM), the focus in recent years has shifted from prototyping to manufacturing fully functional, ultralight, ultrastiff end-use parts. This research investigates the mechanical behavior of octahedral, octet, vertex centroid, dode, diamond, rhombi octahedron, rhombic dodecahedron and solid lattice structured polyacrylate fabricated using Continuous Liquid Interface Production (CLIP) technology based on 3D printing and additive manufacturing processes. The compressive stress-strain behavior of the lattice structures observed is typical of cellular structures which include a region of nominally elastic response, yielding, plastic strain hardening to a peak in strength, followed by a drop in flow stress to a plateau region and finally rapid hardening associated with contact of the deformed struts with each other as part of densification. It was found that the elastic modulus and strength of the various lattice structured materials are proportional to each other. In addition, it was found that the octahedral, octet and diamond lattice structures are amongst the most efficient based on the measured specific stiffness and specific strength.
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Jadhav, S. L., A. L. Jadhav, K. R. Kharat, A. V. Kadam, J. L. Bhosale, and T. S. Magdum. "Effect of Cd2+ Substituted Nickel Ferrite oxide (Ni1-xCdxFe2O4) on Magnetic, Dielectric and Structural Properties." In National Conference on Relevance of Engineering and Science for Environment and Society. AIJR Publisher, 2021. http://dx.doi.org/10.21467/proceedings.118.57.

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The effect of cadmium (Cd2+) substituted at the NiFe2O4 nano materials were this nano material synthesized by auto-combustion technique. The structural analysis confirms that the samples are polycrystalline nature with spinel cubic crystal symmetry. The effect of Cd2+ contains on lattice constants which obeys Vegard's law. The morphological analysis shows that the highly porous structure with spongy like surface morphology. The observed absorption infrared spectra confirm that the exhibits the nano ferrite materials. The magnetic properties measurements reveal that the saturation of magnetization decreases with an increase in constituent Cd2+ in nickel ferrous oxide. The Cd2+ ions present in A-site and Fe3+ are distributed in both tetrahedral and octahedral sites of spinel lattice. The DC measurement shows that the semiconducting behaviour of the prepared Ni1-xCdxFe2O4. The increase in Cd2+ constituent in the nickel ferrite with decrease curie temperature. The dielectric measurement of all samples shows the usual dielectric dispersion with frequency. The impedance spectroscopy analysis suggests grain interior contribution in the conduction process.
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Poumellec, B., and V. M. Mashinsky. "270 nm absorption and 432 nm luminescence bands in doped silica glasses." In Bragg Gratings, Photosensitivity, and Poling in Glass Fibers and Waveguides. Optica Publishing Group, 1997. http://dx.doi.org/10.1364/bgppf.1997.jsue.1.

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There are a lot of structure defects known more or less in pure and doped silica[1]. They appear either in absorption or in fluorescence or also in EPR. In this paper, we are interested in the occurrence of 270 nm absorption and excitation band. This band was mentioned first in a paper in 1982[2]. In this paper, in synthetic GeO2-SiO2 glass containing 0.2 wt% of Ge, the authors have found 270 nm excitation band associated with 435 nm luminescence band. They note that Garrino-Canina[3] have seen a luminescence at 435 nm band but in a much less pure sample. They associate the GeO defect to this band. One year later, Gebala[4] has noticed a 270 nm excitation and 430 nm luminescence band in Ge-P-SiO2. He has associated this to Ge2+ in octahedral coordination.
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