Persistence of the Jahn–Teller distortion of Mo5+ in double perovskites

a structural study of Ba2NdMoO6 and the effect of chemical doping in Ba2Nd1xYxMoO6

E.J. Cussen, William J. Cameron

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Abstract

The cation ordered perovskites Ba2NdMoO6 and Ba2Nd1-xYxMoO6 have been structurally characterised by a combination of neutron and X-ray powder diffraction. Ba2NdMoO6 retains the tetragonal room temperature structure on cooling to 150 K[: I4/m; a = 5.98555(5)Å, c = 8.59510(10) Å] although the MoO6 octahedra distort with an elongation of two, trans Mo-O bonds. Neutron diffraction data collected at T ≤ 130 K show that this compound has undergone a structural distortion to a triclinic space group, although the MoO6 octahedra do not distort any further on cooling below this temperature [at 130 K: ; 5.97625(14) Å, 5.9804(2) Å, 8.59650(13) Å, 89.876(2) °, 89.921(3) °, 89.994(2) °]. The room temperature tetragonal space group symmetry of Ba2NdMoO6 is preserved in the series Ba2Nd1-xYxMoO6 up to composition 0.35 ≤x< 0.5. The lattice parameters converge as the value of x increases until cubic symmetry is reached for the composition for Ba2Nd0.5Y0.5MoO6 [ ;a = 8.4529(3) Å]. Magnetic susceptibility measurements show that all of these compounds display the Curie-Weiss behaviour associated with a fully localised electronic systems. The paramagnetic moments show good agreement with those anticipated to arise from the spin-only contribution from Mo5+ (S=1/2, µso = 1.73 µB) and the moment of 3.62 µB associated with the spin-orbit coupling of the 4I9/2 ground state of Nd3+. For x≤0.125 this series shows a magnetic transition in the range 10 to 15 K indicative of a distortion of the MoO6 octahedra in these compounds that is similar to Ba2NdMoO6.
Original languageEnglish
Pages (from-to)1340-1347
Number of pages8
JournalJournal of Materials Chemistry
Volume20
Issue number7
Early online date11 Dec 2009
DOIs
Publication statusPublished - 2010

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Doping (additives)
Cooling
Neutron diffraction
Chemical analysis
Magnetic susceptibility
X ray powder diffraction
Temperature
Ground state
Lattice constants
Cations
Elongation
Neutrons
Orbits
Positive ions

Keywords

  • cation-ordered perovskites
  • neutron
  • x-ray powder diffraction
  • diffraction
  • organic chemistry

Cite this

@article{593e6289613b45e2bbacbc8d4db506c5,
title = "Persistence of the Jahn–Teller distortion of Mo5+ in double perovskites: a structural study of Ba2NdMoO6 and the effect of chemical doping in Ba2Nd1xYxMoO6",
abstract = "The cation ordered perovskites Ba2NdMoO6 and Ba2Nd1-xYxMoO6 have been structurally characterised by a combination of neutron and X-ray powder diffraction. Ba2NdMoO6 retains the tetragonal room temperature structure on cooling to 150 K[: I4/m; a = 5.98555(5){\AA}, c = 8.59510(10) {\AA}] although the MoO6 octahedra distort with an elongation of two, trans Mo-O bonds. Neutron diffraction data collected at T ≤ 130 K show that this compound has undergone a structural distortion to a triclinic space group, although the MoO6 octahedra do not distort any further on cooling below this temperature [at 130 K: ; 5.97625(14) {\AA}, 5.9804(2) {\AA}, 8.59650(13) {\AA}, 89.876(2) °, 89.921(3) °, 89.994(2) °]. The room temperature tetragonal space group symmetry of Ba2NdMoO6 is preserved in the series Ba2Nd1-xYxMoO6 up to composition 0.35 ≤x< 0.5. The lattice parameters converge as the value of x increases until cubic symmetry is reached for the composition for Ba2Nd0.5Y0.5MoO6 [ ;a = 8.4529(3) {\AA}]. Magnetic susceptibility measurements show that all of these compounds display the Curie-Weiss behaviour associated with a fully localised electronic systems. The paramagnetic moments show good agreement with those anticipated to arise from the spin-only contribution from Mo5+ (S=1/2, µso = 1.73 µB) and the moment of 3.62 µB associated with the spin-orbit coupling of the 4I9/2 ground state of Nd3+. For x≤0.125 this series shows a magnetic transition in the range 10 to 15 K indicative of a distortion of the MoO6 octahedra in these compounds that is similar to Ba2NdMoO6.",
keywords = "cation-ordered perovskites, neutron, x-ray powder diffraction, diffraction, organic chemistry",
author = "E.J. Cussen and Cameron, {William J.}",
year = "2010",
doi = "10.1039/b917579b",
language = "English",
volume = "20",
pages = "1340--1347",
journal = "Journal of Materials Chemistry",
issn = "0959-9428",
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}

Persistence of the Jahn–Teller distortion of Mo5+ in double perovskites : a structural study of Ba2NdMoO6 and the effect of chemical doping in Ba2Nd1xYxMoO6. / Cussen, E.J.; Cameron, William J.

In: Journal of Materials Chemistry, Vol. 20, No. 7, 2010, p. 1340-1347.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Persistence of the Jahn–Teller distortion of Mo5+ in double perovskites

T2 - a structural study of Ba2NdMoO6 and the effect of chemical doping in Ba2Nd1xYxMoO6

AU - Cussen, E.J.

AU - Cameron, William J.

PY - 2010

Y1 - 2010

N2 - The cation ordered perovskites Ba2NdMoO6 and Ba2Nd1-xYxMoO6 have been structurally characterised by a combination of neutron and X-ray powder diffraction. Ba2NdMoO6 retains the tetragonal room temperature structure on cooling to 150 K[: I4/m; a = 5.98555(5)Å, c = 8.59510(10) Å] although the MoO6 octahedra distort with an elongation of two, trans Mo-O bonds. Neutron diffraction data collected at T ≤ 130 K show that this compound has undergone a structural distortion to a triclinic space group, although the MoO6 octahedra do not distort any further on cooling below this temperature [at 130 K: ; 5.97625(14) Å, 5.9804(2) Å, 8.59650(13) Å, 89.876(2) °, 89.921(3) °, 89.994(2) °]. The room temperature tetragonal space group symmetry of Ba2NdMoO6 is preserved in the series Ba2Nd1-xYxMoO6 up to composition 0.35 ≤x< 0.5. The lattice parameters converge as the value of x increases until cubic symmetry is reached for the composition for Ba2Nd0.5Y0.5MoO6 [ ;a = 8.4529(3) Å]. Magnetic susceptibility measurements show that all of these compounds display the Curie-Weiss behaviour associated with a fully localised electronic systems. The paramagnetic moments show good agreement with those anticipated to arise from the spin-only contribution from Mo5+ (S=1/2, µso = 1.73 µB) and the moment of 3.62 µB associated with the spin-orbit coupling of the 4I9/2 ground state of Nd3+. For x≤0.125 this series shows a magnetic transition in the range 10 to 15 K indicative of a distortion of the MoO6 octahedra in these compounds that is similar to Ba2NdMoO6.

AB - The cation ordered perovskites Ba2NdMoO6 and Ba2Nd1-xYxMoO6 have been structurally characterised by a combination of neutron and X-ray powder diffraction. Ba2NdMoO6 retains the tetragonal room temperature structure on cooling to 150 K[: I4/m; a = 5.98555(5)Å, c = 8.59510(10) Å] although the MoO6 octahedra distort with an elongation of two, trans Mo-O bonds. Neutron diffraction data collected at T ≤ 130 K show that this compound has undergone a structural distortion to a triclinic space group, although the MoO6 octahedra do not distort any further on cooling below this temperature [at 130 K: ; 5.97625(14) Å, 5.9804(2) Å, 8.59650(13) Å, 89.876(2) °, 89.921(3) °, 89.994(2) °]. The room temperature tetragonal space group symmetry of Ba2NdMoO6 is preserved in the series Ba2Nd1-xYxMoO6 up to composition 0.35 ≤x< 0.5. The lattice parameters converge as the value of x increases until cubic symmetry is reached for the composition for Ba2Nd0.5Y0.5MoO6 [ ;a = 8.4529(3) Å]. Magnetic susceptibility measurements show that all of these compounds display the Curie-Weiss behaviour associated with a fully localised electronic systems. The paramagnetic moments show good agreement with those anticipated to arise from the spin-only contribution from Mo5+ (S=1/2, µso = 1.73 µB) and the moment of 3.62 µB associated with the spin-orbit coupling of the 4I9/2 ground state of Nd3+. For x≤0.125 this series shows a magnetic transition in the range 10 to 15 K indicative of a distortion of the MoO6 octahedra in these compounds that is similar to Ba2NdMoO6.

KW - cation-ordered perovskites

KW - neutron

KW - x-ray powder diffraction

KW - diffraction

KW - organic chemistry

U2 - 10.1039/b917579b

DO - 10.1039/b917579b

M3 - Article

VL - 20

SP - 1340

EP - 1347

JO - Journal of Materials Chemistry

JF - Journal of Materials Chemistry

SN - 0959-9428

IS - 7

ER -