The atomic and magnetic structures of several iron-substituted rare-earth manganese germanides and stannides

<p>"NdMn_6-xFe_xGe₆ , SmMn_6-xFe_xGe₆ , NdMn_6-xFe_xSn₆ , and SmMn_6-xFe_xSn₆ have been studied by x-ray and neutron diffraction techniques and bulk magnetization measurements. NdMn_6-xFe₆Sn₆ has also been studied by Mӧssbauer spectroscopy. All germanides crystallize in the disordered YCo₆Ge₆-type structure, whereas the stannides crystallize in the HoFe₆Sn₆-type and the TbFe₆Sn₆-type structure for the non-substituted samples and the iron-containing samples, respectively. Iron randomly replaces manganese on all sites in both germanides and stannides. The a, b, and c lattice parameters decrease with increasing iron content for all samples. The net magnetization decreases with increasing iron content for all germanides and the stannides with iron content larger than x = 1.24, whereas the net magnetization increases with increasing iron content for the stannides with iron content less than x = 1.24. The magnetic moment of the iron sublattice couples antiferromagnetically with the ferromagnetically coupled manganese and rare-earth moments for the germanides, whereas there is ferromagnetic coupling between the iron sublattice and the ferromagnetically coupled manganese and rare-earth sublattices for the stannides. Spin reorientation occurs in all neodymium- containing samples in which the easy magnetization direction cants away from the c-axis and the a-axis with increasing temperature for the germanides and the stannides, respectively. The easy magnetization direction of all samarium-containing samples is parallel to, or at least aligned at a small angle with, the basal plane of the unit cell at room temperature. An analysis of the Mn-Mn interatomic distances in RMn₆X₆ and RMn₆-_xFe_xX₆, where R is a rare earth and X is germanium or tin, indicates that there is a critical Mn-Mn distance, d_T ≈ 2.6145 Å, below and above which the coupling within the manganese sublattice is anti ferromagnetic and ferromagnetic, respectively"--Abstract, page iv.</p>

Name thesis:degree_name

Ph. D. in Chemistry

Grantor

University of Missouri--Rolla

Year dc:date.available

2016

Author dc:creator

• Han, Jun

• Chemistry

Repository record dc:identifier

https://scholarsmine.mst.edu/doctoral_dissertations/1364

OAI identifier oai:identifier

oai:scholarsmine.mst.edu:doctoral_dissertations-2366