Investigation of a Structural Phase Transition and Magnetic Structure of Na2BaFe(VO4)2: A Triangular Magnetic Lattice with a Ferromagnetic Ground State

Liurukara D Sanjeewa; Vasile O Garlea; Michael A McGuire; Matthias Frontzek; Colin D McMillen; Kyle Fulle; Joseph W Kolis

doi:10.1021/acs.inorgchem.7b02024

Investigation of a Structural Phase Transition and Magnetic Structure of Na₂BaFe(VO₄)₂: A Triangular Magnetic Lattice with a Ferromagnetic Ground State

Inorg Chem. 2017 Dec 18;56(24):14842-14849. doi: 10.1021/acs.inorgchem.7b02024. Epub 2017 Dec 7.

Authors

Liurukara D Sanjeewa¹, Vasile O Garlea², Michael A McGuire³, Matthias Frontzek², Colin D McMillen¹, Kyle Fulle¹, Joseph W Kolis¹

Affiliations

¹ Department of Chemistry and Center for Optical Materials Science and Engineering Technologies (COMSET), Clemson University , Clemson, South Carolina 29634-0973, United States.
² Neutron Scattering Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
³ Materials Science and Technology Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.

PMID: 29215870
DOI: 10.1021/acs.inorgchem.7b02024

Abstract

The structural and magnetic properties of a glaserite-type Na₂BaFe(VO₄)₂ compound, featuring a triangular magnetic lattice of Fe²⁺ (S = 2), are reported. Temperature dependent X-ray single crystal studies indicate that at room temperature the system adopts a trigonal P3̅m1 structure and undergoes a structural phase transition to a C2/c monoclinic phase slightly below room temperature (T_s = 288 K). This structural transition involves a tilting of Fe-O-V bond angles and strongly influences the magnetic correlation within the Fe triangular lattice. The magnetic susceptibility measurements reveal a ferromagnetic transition near 7 K. Single crystal neutron diffraction confirms the structural distortion and the ferromagnetic spin ordering in Na₂BaFe(VO₄)₂. The magnetic structure of the ordered state is modeled in the magnetic space group C2'/c' that implies a ferromagnetic order of the a and c moment components and antiferromagnetic arrangement for the b components. Overall, the Fe magnetic moments form ferromagnetic layers that are stacked along the c-axis, where the spins point along one of the (111) facets of the FeO₆ octahedron.