Magnetic structures in spinel B-site lattices with ordered diamagnetic ions at the A-sites

Two Different Mechanisms of Metal Cluster Formation in the Rhombohedral Spinel Structures: AlV2O4 and CuZr1.86(1)S4

“…One of the characteristic structural phenomena, particularly observed in geometrically frustrated spinel systems, is the spontaneous formation of high-order atom structuresunusual molecular metal clusters or orbital molecules . Well known examples of such atom clusters in ordered spinel structures are Ti 2 dimers in Mg­Ti 2 O 4 , , decagons in Na 4 ­Ir 3 O 8 , (such decagons are also in Na 3 ­Ir 3 O 8 and in other ordered inorganic structures), trimers in LiVO 2 , “trimerons” in Fe 3 O 4 , − heptamers or trimers + tetramers in AlV 2 O 4 , octamers in CuIr 2 S 4 , tetrahedra in Li­XY 4 O 8 (X = Ga, Fe, In; Y = Cr, Rh), Cr 4 Ga­LiO 8 , Cr 4 In­LiO 8 , Rh 4 In­LiO 8 , Ag 0.5 ­In 0.5 ­Cr 2 S 4 , and Cu 0.5 ­In 0.5 ­Cr 2 S 4 , − and in others. The formation of metal clusters is accompanied by the charge and/or spin and orbital orderings.…”

Structural Mechanism of Cluster Formation in Ordered Chalcogenide Spinels

“…It has been found experimentally that, in a number of ordered crystals, atoms of one type are segregated in the form of clusters. These clusters can form submicroinhomogeneities or microdomains in the terminology proposed in [3][4][5]. Stable atomic segregates have been observed in oxides [6], sulfides, and chalcogenide spinels.…”

“…According to the neutron diffraction data, the size of microdomains is approximately equal to 9 nm for the Ag 1/2 In 1/2 Cr 2 S 4 compound [5] and 20 nm for the Cu 1/2 In 1/2 Cr 2 S 4 compound [4]. The formation of microdomains is accompanied by magnetic phase transitions [3][4][5]. The magnetic phase transitions are preceded by the crystallographic ordering of cations in tetrahedral positions of the spinel structure [3][4][5].…”

“…The formation of microdomains is accompanied by magnetic phase transitions [3][4][5]. The magnetic phase transitions are preceded by the crystallographic ordering of cations in tetrahedral positions of the spinel structure [3][4][5].…”