New Barium Rare-Earth Nickel Oxides:  Synthesis, Crystal Structure, and Magnetic Order

Abstract

Crystals of isostructural R8Ba5Ni4O21 (R = Y, Er, Tm, Yb, and Lu) have been obtained. Conditions for synthesis and stability are reported. The crystal structures of these materials have been established by single-crystal X-ray diffraction: space group I4/m with cell-parameters a =13.713(1) and 13.666(3) Å, c = 5.692(1) and 5.673(2) Å for R = Y and Er, respectively. The compounds contain square NiO5 pyramids, trigonal RO7 prisms capped on one rectangular face, tetragonal bicapped Ba(1)O10 prisms, and irregular Ba(2)O10 polyhedra. A comparison is made between this structure type and those of R2BaNiO5 and R2BaCuO5. Their structure and properties show close relations. The temperature dependence of the magnetic susceptibility from 350 to 1.8 K, measured for R = Y, Yb, and Er, shows the presence of antiferromagnetic ordering for the Yb and Er compounds.

Rare Earth Arenedisulfonate Metal−Organic Frameworks: An Approach toward Polyhedral Diversity and Variety of Functional Compounds

“…Very scarce in hybrid solids, this special coordination is encountered, and although a couple of papers with linkage of truncated rare earth Ln 6 −μ 6 O clusters have been reported, the inorganic network of LnPF-3, reminiscent of those, seems to be unique due to the (Ln 5 −μ 5 -O−H−Ln 5 −μ 5 -O−H···) linkage. Structurally speaking, this kind of association is quite similar to that found in some purely inorganic structures, for instance Ln 8 Ba 5 Ni 4 O 21 , where inside the similar lanthanide pentameric units the central row is formed by a BaO 10 bicapped tetragonal prism in a Ba−O−Ba−O··· sequence instead of that Ln−O−H···Ln of the current compound.

3 Ln(3)−O(15)−H···Ln(3)−O(15)−H··· sequence in LnPF-3.

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“…Despite the existence of Nd-SBU giving rise to structural associations where Nd cations are at relatively short distances, the lack of observed three-dimensional Nd−Nd magnetic interaction is explained to be due to the behavior derived from the inner nature of 4f orbitals of Nd 3+ , which do not favor the magnetic exchange, contrary to the observed situation in other lanthanide-containing structures including 3d cations, too. ,

7 Plots of the reciprocal molar susceptibility (per Nd 3+ mol in corresponding NdPF) as a function of temperature.

8 Room-temperature optical absorption spectra for NdPF-1 (top), NdPF-2 (middle), and NdPF-3 (bottom).

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