화학공학소재연구정보센터
Inorganic Chemistry, Vol.56, No.24, 14842-14849, 2017
Investigation of a Structural Phase Transition and Magnetic Structure of Na2BaFe(VO4)(2): A Triangular Magnetic Lattice with a Ferromagnetic Ground State
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 P (3) over bar m1 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.