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Title: Density functional calculations and analysis of the crystal structure of Pb{sub 2}P{sub 2}O{sub 7}

Abstract

Density functional calculations of the atomic coordinates in crsytalline lead pyrophosphate (Pb{sub 2}P{sub 2}O{sub 7}) are reported. These calculations yield atomic positions differing from a prior x-ray refinement by up to 0.2 A ring . The main difference is a change in the orientation of the (P{sub 2}O{sub 7}){sup 4-} units to bring certain O ions closer to Pb. An analysis of the resulting structure in terms of pair distribution functions is presented. These show that the most significant changes are in the local Pb coordination. The electronic structure is not significantly affected by the change in crystal structure.

Authors:
; ;  [1];  [2];  [2]
  1. Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6032 (United States) and Department of Physics, University of Tennessee, Knoxville, Tennessee 37996-1200 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
20957823
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. B, Condensed Matter and Materials Physics; Journal Volume: 75; Journal Issue: 17; Other Information: DOI: 10.1103/PhysRevB.75.172105; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CRYSTAL STRUCTURE; DENSITY FUNCTIONAL METHOD; DISTRIBUTION FUNCTIONS; ELECTRONIC STRUCTURE; LATTICE PARAMETERS; LEAD; LEAD COMPOUNDS; OXYGEN IONS; PHOSPHATES; X RADIATION

Citation Formats

Suewattana, M., Singh, D. J., Fornari, M., Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6032, and Department of Physics, Central Michigan University, Mt. Pleasant, Michigan 48859. Density functional calculations and analysis of the crystal structure of Pb{sub 2}P{sub 2}O{sub 7}. United States: N. p., 2007. Web. doi:10.1103/PHYSREVB.75.172105.
Suewattana, M., Singh, D. J., Fornari, M., Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6032, & Department of Physics, Central Michigan University, Mt. Pleasant, Michigan 48859. Density functional calculations and analysis of the crystal structure of Pb{sub 2}P{sub 2}O{sub 7}. United States. doi:10.1103/PHYSREVB.75.172105.
Suewattana, M., Singh, D. J., Fornari, M., Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6032, and Department of Physics, Central Michigan University, Mt. Pleasant, Michigan 48859. Tue . "Density functional calculations and analysis of the crystal structure of Pb{sub 2}P{sub 2}O{sub 7}". United States. doi:10.1103/PHYSREVB.75.172105.
@article{osti_20957823,
title = {Density functional calculations and analysis of the crystal structure of Pb{sub 2}P{sub 2}O{sub 7}},
author = {Suewattana, M. and Singh, D. J. and Fornari, M. and Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6032 and Department of Physics, Central Michigan University, Mt. Pleasant, Michigan 48859},
abstractNote = {Density functional calculations of the atomic coordinates in crsytalline lead pyrophosphate (Pb{sub 2}P{sub 2}O{sub 7}) are reported. These calculations yield atomic positions differing from a prior x-ray refinement by up to 0.2 A ring . The main difference is a change in the orientation of the (P{sub 2}O{sub 7}){sup 4-} units to bring certain O ions closer to Pb. An analysis of the resulting structure in terms of pair distribution functions is presented. These show that the most significant changes are in the local Pb coordination. The electronic structure is not significantly affected by the change in crystal structure.},
doi = {10.1103/PHYSREVB.75.172105},
journal = {Physical Review. B, Condensed Matter and Materials Physics},
number = 17,
volume = 75,
place = {United States},
year = {Tue May 01 00:00:00 EDT 2007},
month = {Tue May 01 00:00:00 EDT 2007}
}
  • Density functional calculations of the atomic coordinates in crystalline lead pyrophosphate (Pb{sub 2}P{sub 2}O{sub 7}) are reported. These calculations yield atomic positions differing from a prior x-ray refinement by up to 0.2 Angstroms. The main difference is a change in the orientation of the (P{sub 2}O{sub 7}){sup 4-} units to bring certain O ions closer to Pb. An analysis of the resulting structure in terms of pair distribution functions is presented. These show that the most significant changes are in the local Pb coordination. The electronic structure is not significantly affected by the change in crystal structure.
  • The reaction of Re{sub 2}O{sub 7} with XeF{sub 6} in anhydrous HF provides a convenient route to high-purity ReO{sub 2}F{sub 3}. The fluoride acceptor and Lewis base properties of ReO{sub 2}F{sub 3} have been investigated leading to the formation of [M][ReO{sub 2}F{sub 4}] [M = Li, Na, Cs, N(CH{sub 3}){sub 4}], [K][Re{sub 2}O{sub 4}F{sub 7}], [K][Re{sub 2}O{sub 4}F{sub 7}]{center_dot}2ReO{sub 2}F{sub 3}, [Cs][Re{sub 3}O{sub 6}F{sub 10}], and ReO{sub 2}F{sub 3}(CH{sub 3}CN). The ReO{sub 2}F{sub 4}{sup {minus}}, Re{sub 2}O{sub 4}F{sub 7}{sup {minus}}, and Re{sub 3}O{sub 6}F{sub 10{sup {minus}} anions and the ReO{sub 2}F{sub 3}(CH{sub 3}CN) adduct have been characterized in the solidmore » state by Raman spectroscopy, and the structures [Li][ReO{sub 2}F{sub 4}], [K][Re{sub 2}O{sub 4}F{sub 7}], [K][Re{sub 2}O{sub 4}F{sub 7}]{center_dot}2ReO{sub 2}F{approximately}3}, [Cs][Re{sub 3}O{sub 6}F{sub 10}], and ReO{sub 3}F(CH{sub 3}CN){sub 2}{center_dot}CH{sub 3}CN have been determined by X-ray crystallography. The structure of ReO{sub 2}F{sub 4}{sup {minus}} consists of a cis-dioxo arrangement of Re-O double bonds in which the Re-F bonds trans to the oxygen atoms are significantly lengthened as a result of the trans influence of the oxygens. The Re{sub 2}O{sub 4}F{sub 7}{sup {minus}} and Re{sub 3}O{sub 6}F{sub 10}{sup {minus}} anions and polymeric ReO{sub 2}F{sub 3} are open chains containing fluorine-bridged ReO{sub 2}F{sub 4} units in which each pair of Re-O bonds are cis to each other and the fluorine bridges are trans to oxygens. The trans influence of the oxygens is manifested by elongated terminal Re-F bonds trans to Re-O bonds as in ReO{sub 2}F{sub 4}{sup {minus}} and by the occurrence of both fluorine bridges trans to Re-O bonds. Fluorine-19 NMR spectra show that ReO{sub 2}F{sub 4}{sup {minus}}, Re{sub 2}O{sub 4}F{sub 7}{sup {minus}}, and ReO{sub 2}F{sub 3}(CH{sub 3}CN) have cis-dioxo arrangements in CH{sub 3}CN solution. Density functional theory calculations at the local and nonlocal levels confirm that the cis-dioxo isomers of ReO{sub 2}F{sub 4}{sup {minus}} and ReO{sub 2}F{sub 3}(CH{sub 3}CN), where CH{sub 3}CN is bonded trans to an oxygen, are the energy-minimized structures. The adduct ReO{sub 3}F(CH{sub 3}CN){sub 2}{center_dot}CH{sub 3}CN was obtained by hydrolysis of ReO{sub 2}F{sub 3}(CH{sub 3}CN), and was shown by X-ray crystallography to have a facial arrangement of oxygen atoms on rhenium.« less
  • The bifunctional (sulfonylmethyl)phosphonates (i-C{sub 3}H{sub 7}O){sub 2}P(O)CH{sub 2}S(I){sub 2}C{sub 6}H{sub 11}, (i-C{sub 3}H{sub 7}O){sub 2}P(O)CH{sub 2}S(O){sub 2}(p-CH{sub 3}C{sub 6}H{sub 4}), and (C{sub 6}H{sub 5}){sub 2}P(O)CH{sub 2}S(O){sub 2}N(CH{sub 3}){sub 2} and (sulfinylmethyl)phosphonate (i-C{sub 3}H{sub 7}O){sub 2}P(O)CH{sub 2}S(O)(p-CH{sub 3}C{sub 6}H{sub 4}) have been synthesized. The ligands have been characterized by spectroscopic methods, and selected coordination chemistry with UO{sub 2}(NO{sub 3}){sub 2}, La(NO{sub 3}){sub 3}, and Gd(NO{sub 3}){sub 3} has been evaluated. The structures of two complexes, UO{sub 2}(NO{sub 3}){sub 2}((i-C{sub 3}H{sub 7}O){sub 2}P(O)CH{sub 2}S(O){sub 2}C{sub 6}H{sub 11}){sub 2} (2) and Gd(NO{sub 3}){sub 3}((i-C{sub 3}H{sub 7}O){sub 2}P(O)CH{sub 2}S(O)(p-CH{sub 3}C{sub 6}H{sub 4})){center dot}H{sub 2}Omore » (8), have been determined by single-crystal x-ray diffraction techniques at 23{degree}C, and the crystal parameters are reported. The molecular structures of the two complexes are also reported. 25 refs., 2 figs., 4 tabs.« less
  • Two new mixed valent Mo(III)/Mo(IV) diphosphates containing lead Pb{sub 2}(PbO){sub 2}Mo{sub 8}(P{sub 2}O{sub 7}){sub 8} and PbK{sub 2}Mo{sub 8}(P{sub 2}O{sub 7}){sub 8} have been synthesized. The [Mo{sub 8}P{sub 16}O{sub 56}]{infinity} frameworks of these phosphates are closely related to that of K{sub 0.17}MoP{sub 2}O{sub 7}: the MoO{sub 6} octahedra and P{sub 2}O{sub 7} groups form two sorts of large eight-sided tunnels. They are occupied in an ordered way by PbO chains and Pb{sup 2+} cations in Pb{sub 2}(PbO){sub 2}Mo{sub 8}(P{sub 2}O{sub 7}){sub 8} and by K{sup +} and Pb{sup 2+} cations in PbK{sub 2}Mo{sub 8}(P{sub 2}O{sub 7}){sub 8}. It results inmore » different symmetries of these two structures, which are tetragonal and monoclinic, respectively, showing the great flexibility of these mixed frameworks, susceptible to accommodate various species with different sizes. - Graphical abstract: The [Mo{sub 8}P{sub 16}O{sub 56}]{infinity} framework showing the two kinds of eight-sided tunnels able to accept univalent or divalent ions.« less
  • We report the structural and magnetic characterizations of Ba{sub 3}TeCo{sub 3}P{sub 2}O{sub 14}, Pb{sub 3}TeCo{sub 3}P{sub 2}O{sub 14}, and Pb{sub 3}TeCo{sub 3}V{sub 2}O{sub 14}, compounds that are based on the mineral dugganite, which is isostructural to langasites. The magnetic part of the structure consists of layers of Co{sup 2+} triangles. Nuclear and magnetic structures were determined through a co-refinement of synchrotron and neutron powder diffraction data. In contrast to the undistorted P321 langasite structure of Ba{sub 3}TeCo{sub 3}P{sub 2}O{sub 14}, a complex structural distortion yielding a large supercell is found for both Pb{sub 3}TeCo{sub 3}P{sub 2}O{sub 14} and Pb{sub 3}TeCo{submore » 3}V{sub 2}O{sub 14}. Comparison of the three compounds studied along with the zinc analog Pb{sub 3}TeZn{sub 3}P{sub 2}O{sub 14}, also characterized here, suggests that the distortion is driven by Pb{sup 2+} lone pairs; as such, the Pb compounds crystallize in a pyroelectric space group, P2. Magnetic susceptibility, magnetization, and heat capacity measurements were performed to characterize the magnetic behavior. All three compounds become antiferromagnetic with Néel temperatures T{sub N}≈21 K (Ba{sub 3}TeCo{sub 3}P{sub 2}O{sub 14}), ≈13 K (Pb{sub 3}TeCo{sub 3}P{sub 2}O{sub 14}), and ≈8 K (Pb{sub 3}TeCo{sub 3}V{sub 2}O{sub 14}), and they exhibit magnetic transitions at high applied magnetic fields, suggesting intrinsically complex magnetic behavior for tetrahedrally coordinated d{sup 7} Co{sup 2+} in this structure type. - Graphical abstract: Ba{sub 3}TeCo{sub 3}P{sub 2}O{sub 14}, Pb{sub 3}TeCo{sub 3}P{sub 2}O{sub 14} and Pb{sub 3}TeCo{sub 3}V{sub 2}O{sub 14} exhibit a triangles-of-triangles arrangement of the magnetic cations. Despite the Pb-induced crystallographic distortion, all of these materials exhibit competing antiferromagnetic and ferromagnetic interactions that lead to complex high field magnetism. - Highlights: • Nuclear and magnetic structures of Ba{sub 3}TeCo{sub 3}P{sub 2}O{sub 14}, Pb{sub 3}TeCo{sub 3}P{sub 2}O{sub 14} and Pb{sub 3}TeCo{sub 3}V{sub 2}O{sub 14}. • Structural characterization shows complex Pb-induced distortion. • Distortion puts Pb-compounds into space group that allows potential multiferroicity. • Magnetic characterization shows competing magnetic interactions. • Triangles of triangles motif results in complex high-field magnetic behavior.« less