Nuclear and magnetic structure of U{sub 3}Ga{sub 2}Ge{sub 3}: A neutron powder diffraction study

Rogl, P; Andre, G; Weitzer, F

doi:10.1006/jssc.1997.7346

Title: Nuclear and magnetic structure of U{sub 3}Ga{sub 2}Ge{sub 3}: A neutron powder diffraction study

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Abstract

The crystal structure of U{sub 3}Ga{sub 2}Ge{sub 3} has been investigated by means of neutron powder diffractometry in the range from 1.5 to 100 K. Full matrix full profile refinements of the nuclear structure at 100 K revealed a new structure type with almost fully ordered distribution of Ga and Ge atoms in the 8c sites of space group I4. The new U{sub 3}Ga{sub 2}Ge{sub 3} type is a low symmetry derivative of the ordered antitype-Cr{sub 5}B{sub 3} (I4/mcm), R{sub 1} = 0.032, R{sub F} = 0.030. From model refinements, eventual interstitial nonmetal occupation in the metal octahedra U{sub 1}Ge{sub 1}Ge{sub 2}Ga{sub 2} or U{sub 2}Ge{sub 2}Ga{sub 2} or in metal tetrahedra Ge{sub 2}Ga{sub 2} is ruled out. At temperatures lower than T{sub c} = 90 K uranium atoms order ferromagnetically as monitored by the intensity of the magnetic reflection {sup M}I{sub (011)}. Due to the observation of the {sup M}(011) reflection, the magnetic spin structure is consistent with the symmetry of the noncentrosymmetric space group I422. The lower symmetry invokes a splitting of the 4a sites of the parent Cr{sub 5}B{sub 3} type (I4/mcm) into two twofold uranium sites 2a and 2b of I422. Besides the uranium atoms inmore »« less

Authors:

Rogl, P ^[1]; Andre, G ^[1]; Weitzer, F ^[2]

CEA-CEN, Saclay (France)
Universitaet Wien (Austria); and others

Publication Date:: Sun Jun 01 00:00:00 EDT 1997

OSTI Identifier:: 589023

Resource Type:: Journal Article

Journal Name:: Journal of Solid State Chemistry

Additional Journal Information:: Journal Volume: 131; Journal Issue: 1; Other Information: PBD: Jun 1997

Country of Publication:: United States

Language:: English

Subject:: 36 MATERIALS SCIENCE; 66 PHYSICS; CRYSTAL STRUCTURE; NUCLEAR STRUCTURE; REFLECTION; URANIUM COMPOUNDS; GERMANIDES; GALLIUM COMPOUNDS; NEUTRON DIFFRACTION

Citation Formats


                    Rogl, P, Universitaet Wien, Andre, G, and Weitzer, F. Nuclear and magnetic structure of U{sub 3}Ga{sub 2}Ge{sub 3}: A neutron powder diffraction study.  United States: N. p., 1997. 
        Web.  doi:10.1006/jssc.1997.7346.

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                    Rogl, P, Universitaet Wien, Andre, G, & Weitzer, F. Nuclear and magnetic structure of U{sub 3}Ga{sub 2}Ge{sub 3}: A neutron powder diffraction study.  United States.  https://doi.org/10.1006/jssc.1997.7346

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                    Rogl, P, Universitaet Wien, Andre, G, and Weitzer, F. 1997.  
        "Nuclear and magnetic structure of U{sub 3}Ga{sub 2}Ge{sub 3}: A neutron powder diffraction study".  United States.  https://doi.org/10.1006/jssc.1997.7346.

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@article{osti_589023,

  title        = {Nuclear and magnetic structure of U{sub 3}Ga{sub 2}Ge{sub 3}: A neutron powder diffraction study},

  author       = {Rogl, P and Universitaet Wien and Andre, G and Weitzer, F},

  abstractNote = {The crystal structure of U{sub 3}Ga{sub 2}Ge{sub 3} has been investigated by means of neutron powder diffractometry in the range from 1.5 to 100 K. Full matrix full profile refinements of the nuclear structure at 100 K revealed a new structure type with almost fully ordered distribution of Ga and Ge atoms in the 8c sites of space group I4. The new U{sub 3}Ga{sub 2}Ge{sub 3} type is a low symmetry derivative of the ordered antitype-Cr{sub 5}B{sub 3} (I4/mcm), R{sub 1} = 0.032, R{sub F} = 0.030. From model refinements, eventual interstitial nonmetal occupation in the metal octahedra U{sub 1}Ge{sub 1}Ge{sub 2}Ga{sub 2} or U{sub 2}Ge{sub 2}Ga{sub 2} or in metal tetrahedra Ge{sub 2}Ga{sub 2} is ruled out. At temperatures lower than T{sub c} = 90 K uranium atoms order ferromagnetically as monitored by the intensity of the magnetic reflection {sup M}I{sub (011)}. Due to the observation of the {sup M}(011) reflection, the magnetic spin structure is consistent with the symmetry of the noncentrosymmetric space group I422. The lower symmetry invokes a splitting of the 4a sites of the parent Cr{sub 5}B{sub 3} type (I4/mcm) into two twofold uranium sites 2a and 2b of I422. Besides the uranium atoms in 8j ({mu}{sub U} = 2.57{mu}{sub B}), only the uranium atoms in 2a were found to carry a magnetic moment {mu}{sub U} = 2.45{mu}{sub B}. All moments are parallel to the crystallographic a axis. To comply with the symmetry of the Ge/Ga atoms, magnetic and nuclear structure have to be described in space group I4. The reliability values for :the 1.5 K diffractogram were: R{sub I} = 0.024, R{sub F} = 0.019, and R{sub mag} = 0.033.},

  doi          = {10.1006/jssc.1997.7346},

  url          = {https://www.osti.gov/biblio/589023},
  journal      = {Journal of Solid State Chemistry},
number       = 1,

  volume       = 131,

  place        = {United States},

  year         = {Sun Jun 01 00:00:00 EDT 1997},

  month        = {Sun Jun 01 00:00:00 EDT 1997}

}

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