Magnetic order arising from structural distortion: the structure and magnetic properties of Ba2LnMoO6

E. Cussen, D.R. Lynham, J. Rogers

Research output: Contribution to journalArticle

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Abstract

The compounds Ba2LnMoO6 (Ln ) Nd, Sm, Eu, Gd, Dy, Y, Er, and Yb) have been synthesized by solid-state techniques under reducing conditions at temperatures up to 1300 °C. Rietveld analyses of X-ray and neutron powder diffraction data show that these compounds adopt cation-ordered perovskite
phases. At room temperature Ba2NdMoO6 and Ba2SmMoO6 adopt tetragonally distorted structures in the space groups I4/m and I4/mmm, respectively, while the data collected from all other compounds could be fitted in the cubic space group Fm3hm. Bond valence sums show that the observed tetragonal distortions
are driven by the bonding requirements of Ba2+. Neutron powder diffraction data collected below TN ) 15(1) K show that Ba2NdMoO6 is triclinically distorted (I1h: a ) 5.9790(2) Å, b ) 5.9840(2) Å, c ) 8.6024(2) Å, R ) 89.854(2)°, â ) 90.056(5)°, ç ) 90.003(5)°) and that Nd3+ and Mo5+ are antiferromagnetically ordered. Magnetic susceptibility data show that this compound behaves as a Curie-
Weiss paramagnet above this temperature, and no other compounds in the series show evidence of magnetic order down to 2 K. Ba2YMoO6 and Ba2YbMoO6 both remain entirely paramagnetic to 2 K due to perfect geometric frustration of the cubic lattice, indicating that next-nearest-neighbor interactions between like cations dominate over nearest-neighbor Mo-O-Ln exchange. The magnetic structure of Ba2NdMoO6 is rationalized with reference to the splitting of the t2g manifold of Mo5+ by the Jahn-Teller distortion and
the associated introduction of anisotropic magnetic superexchange.
LanguageEnglish
Pages2855-2866
Number of pages12
JournalChemistry of Materials
Volume18
DOIs
Publication statusPublished - 2006

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Magnetic properties
Neutron powder diffraction
Cations
Positive ions
Jahn-Teller effect
Magnetic structure
Magnetic susceptibility
X ray powder diffraction
Temperature
Ion exchange

Keywords

  • chemistry
  • Perovskite

Cite this

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title = "Magnetic order arising from structural distortion: the structure and magnetic properties of Ba2LnMoO6",
abstract = "The compounds Ba2LnMoO6 (Ln ) Nd, Sm, Eu, Gd, Dy, Y, Er, and Yb) have been synthesized by solid-state techniques under reducing conditions at temperatures up to 1300 °C. Rietveld analyses of X-ray and neutron powder diffraction data show that these compounds adopt cation-ordered perovskitephases. At room temperature Ba2NdMoO6 and Ba2SmMoO6 adopt tetragonally distorted structures in the space groups I4/m and I4/mmm, respectively, while the data collected from all other compounds could be fitted in the cubic space group Fm3hm. Bond valence sums show that the observed tetragonal distortionsare driven by the bonding requirements of Ba2+. Neutron powder diffraction data collected below TN ) 15(1) K show that Ba2NdMoO6 is triclinically distorted (I1h: a ) 5.9790(2) {\AA}, b ) 5.9840(2) {\AA}, c ) 8.6024(2) {\AA}, R ) 89.854(2)°, {\^a} ) 90.056(5)°, {\cc} ) 90.003(5)°) and that Nd3+ and Mo5+ are antiferromagnetically ordered. Magnetic susceptibility data show that this compound behaves as a Curie-Weiss paramagnet above this temperature, and no other compounds in the series show evidence of magnetic order down to 2 K. Ba2YMoO6 and Ba2YbMoO6 both remain entirely paramagnetic to 2 K due to perfect geometric frustration of the cubic lattice, indicating that next-nearest-neighbor interactions between like cations dominate over nearest-neighbor Mo-O-Ln exchange. The magnetic structure of Ba2NdMoO6 is rationalized with reference to the splitting of the t2g manifold of Mo5+ by the Jahn-Teller distortion andthe associated introduction of anisotropic magnetic superexchange.",
keywords = "chemistry , Perovskite",
author = "E. Cussen and D.R. Lynham and J. Rogers",
year = "2006",
doi = "10.1021/cm0602388",
language = "English",
volume = "18",
pages = "2855--2866",
journal = "Chemistry of Materials",
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Magnetic order arising from structural distortion: the structure and magnetic properties of Ba2LnMoO6. / Cussen, E.; Lynham, D.R.; Rogers, J.

In: Chemistry of Materials, Vol. 18, 2006, p. 2855-2866.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Magnetic order arising from structural distortion: the structure and magnetic properties of Ba2LnMoO6

AU - Cussen, E.

AU - Lynham, D.R.

AU - Rogers, J.

PY - 2006

Y1 - 2006

N2 - The compounds Ba2LnMoO6 (Ln ) Nd, Sm, Eu, Gd, Dy, Y, Er, and Yb) have been synthesized by solid-state techniques under reducing conditions at temperatures up to 1300 °C. Rietveld analyses of X-ray and neutron powder diffraction data show that these compounds adopt cation-ordered perovskitephases. At room temperature Ba2NdMoO6 and Ba2SmMoO6 adopt tetragonally distorted structures in the space groups I4/m and I4/mmm, respectively, while the data collected from all other compounds could be fitted in the cubic space group Fm3hm. Bond valence sums show that the observed tetragonal distortionsare driven by the bonding requirements of Ba2+. Neutron powder diffraction data collected below TN ) 15(1) K show that Ba2NdMoO6 is triclinically distorted (I1h: a ) 5.9790(2) Å, b ) 5.9840(2) Å, c ) 8.6024(2) Å, R ) 89.854(2)°, â ) 90.056(5)°, ç ) 90.003(5)°) and that Nd3+ and Mo5+ are antiferromagnetically ordered. Magnetic susceptibility data show that this compound behaves as a Curie-Weiss paramagnet above this temperature, and no other compounds in the series show evidence of magnetic order down to 2 K. Ba2YMoO6 and Ba2YbMoO6 both remain entirely paramagnetic to 2 K due to perfect geometric frustration of the cubic lattice, indicating that next-nearest-neighbor interactions between like cations dominate over nearest-neighbor Mo-O-Ln exchange. The magnetic structure of Ba2NdMoO6 is rationalized with reference to the splitting of the t2g manifold of Mo5+ by the Jahn-Teller distortion andthe associated introduction of anisotropic magnetic superexchange.

AB - The compounds Ba2LnMoO6 (Ln ) Nd, Sm, Eu, Gd, Dy, Y, Er, and Yb) have been synthesized by solid-state techniques under reducing conditions at temperatures up to 1300 °C. Rietveld analyses of X-ray and neutron powder diffraction data show that these compounds adopt cation-ordered perovskitephases. At room temperature Ba2NdMoO6 and Ba2SmMoO6 adopt tetragonally distorted structures in the space groups I4/m and I4/mmm, respectively, while the data collected from all other compounds could be fitted in the cubic space group Fm3hm. Bond valence sums show that the observed tetragonal distortionsare driven by the bonding requirements of Ba2+. Neutron powder diffraction data collected below TN ) 15(1) K show that Ba2NdMoO6 is triclinically distorted (I1h: a ) 5.9790(2) Å, b ) 5.9840(2) Å, c ) 8.6024(2) Å, R ) 89.854(2)°, â ) 90.056(5)°, ç ) 90.003(5)°) and that Nd3+ and Mo5+ are antiferromagnetically ordered. Magnetic susceptibility data show that this compound behaves as a Curie-Weiss paramagnet above this temperature, and no other compounds in the series show evidence of magnetic order down to 2 K. Ba2YMoO6 and Ba2YbMoO6 both remain entirely paramagnetic to 2 K due to perfect geometric frustration of the cubic lattice, indicating that next-nearest-neighbor interactions between like cations dominate over nearest-neighbor Mo-O-Ln exchange. The magnetic structure of Ba2NdMoO6 is rationalized with reference to the splitting of the t2g manifold of Mo5+ by the Jahn-Teller distortion andthe associated introduction of anisotropic magnetic superexchange.

KW - chemistry

KW - Perovskite

UR - http://dx.doi.org/10.1021/cm0602388

U2 - 10.1021/cm0602388

DO - 10.1021/cm0602388

M3 - Article

VL - 18

SP - 2855

EP - 2866

JO - Chemistry of Materials

T2 - Chemistry of Materials

JF - Chemistry of Materials

SN - 0897-4756

ER -