Understanding of the structural chemistry in the uranium oxo-tellurium system under HT/HP conditions.

The study of phase formation in the U-Te-O systems with mono and divalent cations under high-temperature high-pressure (HT/HP) conditions has resulted in four new inorganic compounds: K [(UO) (TeO)], Mg [(UO) (TeO)], Sr [(UO) (TeO)] and Sr [(UO) (TeO)]. Tellurium occurs as Te, Te, and Te in these phases which demonstrate the high chemical flexibility of the system. Uranium VI) adopts a variety of coordinations, namely, UO in K [(UO) (TeO), UO in Mg [(UO) (TeO)] and Sr [(UO) (TeO)], and UO in Sr [(UO) (TeO)]. The structure of K [(UO) (TeO)] is featured with one dimensional (1D) [TeO] chains along the -axis. The TeO chains are further linked by UO polyhedra, forming the 3D [(UO) (TeO)] anionic frameworks. In Mg [(UO) (TeO)], TeO disphenoids share common corners with each other resulting in infinite 1D chains of [(TeO)] propagating along the -axis. These chains link the uranyl bipyramids by edge sharing along two edges of the disphenoids, resulting in the 2D layered structure of [(UO) (TeO)]. The structure of Sr [(UO) (TeO)] is based on 1D chains of [(UO) (TeO)] propagating into the -axis. These chains are formed by edge-sharing uranyl bipyramids which are additionally fused together by two TeO disphenoids, which also share two edges. The 3D framework structure of Sr [(UO) (TeO)] is composed of 1D [TeO] chains sharing edges with UO bipyramids. Three tunnels based on 6-Membered rings (MRs) are propagating along [001] [010] and [100] directions. The HT/HP synthetic conditions for the preparation of single crystalline samples and their structural aspects are discussed in this work.