Expanding Family of Litharge-Derived Sulfate Minerals and Synthetic Compounds: Preparation and Crystal Structures of [Bi2CuO3]SO4 and [Ln2O2]SO4 (Ln = Dy and Ho)

Oleg Siidra,Igor Plokhikh,Evgeny Nazarchuk,Astrid Holzheid,Dmitri Charkin,Georgy Akimov

doi:10.3390/min10100887

Oleg Siidra, Igor Plokhikh + Show 4 more

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https://doi.org/10.3390/min10100887

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Abstract

During the last decades, layered structures have attracted particular and increasing interest due to the multitude of outstanding properties exhibited by their representatives. Particularly common among their archetypes, with a significant number of mineral and synthetic species structural derivatives, is that of litharge. In the current paper, we report the structural studies of two later rare-earth oxysulfates, [Ln2O2]SO4 (Ln = Dy, Ho), which belong indeed to the grandreefite family, and a novel compound [Bi2CuO3]SO4, which belongs to a new structure type and demonstrates the second example of Cu2+ incorporation into litharge-type slabs. Crystals of [Bi2CuO3]SO4 were obtained under high-pressure/high-temperature (HP/HT) conditions, whereas polycrystalline samples of [Ln2O2]SO4 (Ln = Dy, Ho) compounds were prepared via an exchange solid-state reaction. The crystal structure of [Bi2CuO3]SO4 is based on alternation of continuous [Bi2CuO3]2+ layers of edge-sharing OBi2Cu2 and OBi3Cu tetrahedra and sheets of sulfate groups. Cu2+ cations are in cis position in O5Bi2Cu2 and O6Bi2Cu2 oxocentered tetrahedra in litharge slab. The crystal structure of [Ln2O2]SO4 (Ln = Dy, Ho) is completely analogous to those of grandreefite and oxysulfates of La, Sm, Eu, and Bi.

Highlights

Litharge-derived architectures are widely represented by both mineral and synthetic species exhibiting exceptional structural and chemical diversity, as well as a variety of properties
We report the structural studies of two later rare-earth oxysulfates, [Ln2 O2 ]SO4 (Ln = Dy, Ho), which belong to the grandreefite family, and a novel compound [Bi2 CuO3 ]SO4, which belongs to a new structure type and demonstrates the second example of Cu2+ incorporation into litharge-type slabs
The tetrahedral sulfate, selenate, chromate, and molybdate anions are yet the largest species which can be accommodated in the space between metal-oxide or metal-fluoride litharge slabs

Summary

Introduction

Litharge-derived architectures are widely represented by both mineral and synthetic species exhibiting exceptional structural and chemical diversity, as well as a variety of properties. Pb2+ and Bi3+ , which favors their “one-sided” coordination The majority of both synthetic and mineral contributions come from the chemistry of oxides [1,2,3] and oxyhalides [4,5,6,7,8,9,10,11,12,13,14,15,16,17,18], most commonly the representatives of the so-called Sillén family. The latter generally correspond to ordered alternations of litharge-derived slabs and single or double sheets of monoatomic anions of Group 15–17 elements.

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