Synthesis and magnetic susceptibility of the rutile phase MnTaO4

Selective Crystal Growth and Structural, Optical, and Electronic Studies of Mn3Ta2O8

“…One example of a structure with such a complex network is the unusual and rare, anion-deficient, fluorite-related phase that is only exhibited, to the authors’ knowledge, by Ga 3– x In 5+ x Sn 2 O 16 (where 0.3 ≤ x ≤ 1.6), Na 5 Ln­(WO 4 ) 4 (where Ln = Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu), and Mn 3 Ta 2 O 8 . − This CCTN maintains four distinct cation environments, four-, six-, seven-, and eight-coordinate, and a wide array of oxidation states, ranging from 1+ to 6+. In particular, Mn 3 Ta 2 O 8 provides a challenge for single-crystal growth, owing to the similarities in the stoichiometry and the differences in the structure of the ternaries in the Mn–Ta–O phase space, as shown in Figure . ,,− Most of the known phases have only been characterized via powder X-ray diffraction (XRD), often in the presence of secondary phases, and vary widely in structure, including fluorite-related compositions such as Mn 3 Ta 2 O 8 , as well as the η-carbide, columbite, corundum, corundum/rock salt, CoSn, rutile, tantalite, trirutile, wodginite, and wolframite structure types. ,,,, Single-crystal growth of ternaries in this system has been most successful in producing what are reported to be metastable structures, which are polymorphs of the reported stable structures of identical stoichiometry (MnTa 2 O 6 , Mn 4 Ta 2 O 9 , and Mn 11 Ta 4 O 21 ) obtained via solid-state syntheses . To date, only a single instance of a ternary manganese tantalate crystal that is classified as thermodynamically favored has been grown, to the authors’ knowledge: the anion-deficient fluorite Mn 0.55 Ta 0.45 O 1.7 .…”