Retention of a Paramagnetic Ground State at Low Temperatures in a Family of Structurally Related UIV Phosphates

Unique 3D framework formed by adding MIIO4 groups into high Sb/P ratio phosphatoantimonates

Explorations on a mixed metal phosphatoantimonate system led to the discovery of two new anhydrous phosphatoantimonates, namely, Cs4MSb6P4O28 (M=Mg, Zn), which represent the first examples of quinary AI – MII –SbV – PV– O systems. Single-crystal structure analysis reveals that the two title compounds crystallize in the tetragonal space group I41/a (No. 88). Their structures feature complicated 3D frameworks with interesting tunnel structures comprised of corner sharing MO4 tetrahedra, SbO6 octahedra and PO4 tetrahedra, with the Cs+ cations sitting in the tunnels to balance the valence. Optical reflectance spectrum measurements show that these two compounds are insulators with band gaps of about 4.5 eV.

Breaking a Paradigm: Observation of Magnetic Order in the Purple U(IV) Phosphite: U(HPO3)2

The hydrothermal crystal growth of a new uranium phosphite, U(HPO₃)₂, is reported. This material was found to exhibit optical and magnetic properties not commonly observed in U(IV) containing materials, specifically purple coloration and low temperature magnetism. We discuss the synthesis, structure determination, and characterization of the title compound and comment on its optical, thermal, and magnetic properties. The magnetic behavior is consistent with frustrated antiferromagnetism that arises from the hexagonal honeycomb lattice of U(IV) ions. This material gives rare evidence for U(IV) ions participating in magnetic order.

One-dimensional chain structures of hexanuclear uranium(iv) clusters bridged by formate ligands

Three one-dimensional chain structures of uranium(iv) hexanuclear clusters have been synthesized under hydrothermal/solvothermal conditions.