3 research outputs found
The Role of OrderāDisorder Transitions in the Quest for Molecular Multiferroics: Structural and Magnetic Neutron Studies of a Mixed Valence Iron(II)āIron(III) Formate Framework
Neutron
diffraction studies have been carried out to shed light
on the unprecedented orderādisorder phase transition (ca. 155
K) observed in the mixed-valence ironĀ(II)āironĀ(III) formate
framework compound [NH<sub>2</sub>(CH<sub>3</sub>)<sub>2</sub>]<sub><i>n</i></sub>[Fe<sup>III</sup>Fe<sup>II</sup>(HCOO)<sub>6</sub>]<sub><i>n</i></sub>. The crystal structure at 220
K was first determined from Laue diffraction data, then a second refinement
at 175 K and the crystal structure determination in the low temperature
phase at 45 K were done with data from the monochromatic high resolution
single crystal diffractometer D19. The 45 K nuclear structure reveals
that the phase transition is associated with the orderādisorder
of the dimethylammonium counterion that is weakly anchored in the
cavities of the [Fe<sup>III</sup>Fe<sup>II</sup>(HCOO)<sub>6</sub>]<sub><i>n</i></sub> framework. In the low-temperature
phase, a change in space group from <i>P</i>3Ģ
1<i>c</i> to <i>R</i>3Ģ
<i>c</i> occurs,
involving a tripling of the <i>c</i>-axis due to the ordering
of the dimethylammonium counterion. The occurrence of this nuclear
phase transition is associated with an electric transition, from paraelectric
to antiferroelectric. A combination of powder and single crystal neutron
diffraction measurements below the magnetic order transition (ca.
37 K) has been used to determine unequivocally the magnetic structure
of this NeĢel N-Type ferrimagnet, proving that the ferrimagnetic
behavior is due to a noncompensation of the different Fe<sup>II</sup> and Fe<sup>III</sup> magnetic moments
The Role of OrderāDisorder Transitions in the Quest for Molecular Multiferroics: Structural and Magnetic Neutron Studies of a Mixed Valence Iron(II)āIron(III) Formate Framework
Neutron
diffraction studies have been carried out to shed light
on the unprecedented orderādisorder phase transition (ca. 155
K) observed in the mixed-valence ironĀ(II)āironĀ(III) formate
framework compound [NH<sub>2</sub>(CH<sub>3</sub>)<sub>2</sub>]<sub><i>n</i></sub>[Fe<sup>III</sup>Fe<sup>II</sup>(HCOO)<sub>6</sub>]<sub><i>n</i></sub>. The crystal structure at 220
K was first determined from Laue diffraction data, then a second refinement
at 175 K and the crystal structure determination in the low temperature
phase at 45 K were done with data from the monochromatic high resolution
single crystal diffractometer D19. The 45 K nuclear structure reveals
that the phase transition is associated with the orderādisorder
of the dimethylammonium counterion that is weakly anchored in the
cavities of the [Fe<sup>III</sup>Fe<sup>II</sup>(HCOO)<sub>6</sub>]<sub><i>n</i></sub> framework. In the low-temperature
phase, a change in space group from <i>P</i>3Ģ
1<i>c</i> to <i>R</i>3Ģ
<i>c</i> occurs,
involving a tripling of the <i>c</i>-axis due to the ordering
of the dimethylammonium counterion. The occurrence of this nuclear
phase transition is associated with an electric transition, from paraelectric
to antiferroelectric. A combination of powder and single crystal neutron
diffraction measurements below the magnetic order transition (ca.
37 K) has been used to determine unequivocally the magnetic structure
of this NeĢel N-Type ferrimagnet, proving that the ferrimagnetic
behavior is due to a noncompensation of the different Fe<sup>II</sup> and Fe<sup>III</sup> magnetic moments
The Role of OrderāDisorder Transitions in the Quest for Molecular Multiferroics: Structural and Magnetic Neutron Studies of a Mixed Valence Iron(II)āIron(III) Formate Framework
Neutron
diffraction studies have been carried out to shed light
on the unprecedented orderādisorder phase transition (ca. 155
K) observed in the mixed-valence ironĀ(II)āironĀ(III) formate
framework compound [NH<sub>2</sub>(CH<sub>3</sub>)<sub>2</sub>]<sub><i>n</i></sub>[Fe<sup>III</sup>Fe<sup>II</sup>(HCOO)<sub>6</sub>]<sub><i>n</i></sub>. The crystal structure at 220
K was first determined from Laue diffraction data, then a second refinement
at 175 K and the crystal structure determination in the low temperature
phase at 45 K were done with data from the monochromatic high resolution
single crystal diffractometer D19. The 45 K nuclear structure reveals
that the phase transition is associated with the orderādisorder
of the dimethylammonium counterion that is weakly anchored in the
cavities of the [Fe<sup>III</sup>Fe<sup>II</sup>(HCOO)<sub>6</sub>]<sub><i>n</i></sub> framework. In the low-temperature
phase, a change in space group from <i>P</i>3Ģ
1<i>c</i> to <i>R</i>3Ģ
<i>c</i> occurs,
involving a tripling of the <i>c</i>-axis due to the ordering
of the dimethylammonium counterion. The occurrence of this nuclear
phase transition is associated with an electric transition, from paraelectric
to antiferroelectric. A combination of powder and single crystal neutron
diffraction measurements below the magnetic order transition (ca.
37 K) has been used to determine unequivocally the magnetic structure
of this NeĢel N-Type ferrimagnet, proving that the ferrimagnetic
behavior is due to a noncompensation of the different Fe<sup>II</sup> and Fe<sup>III</sup> magnetic moments