Hydrothermal Synthesis and Structural Investigation of a Crystalline Uranyl Borosilicate

Abstract

The relevance of multidimensional and porous crystalline materials to nuclear waste remediation and storage applications has motivated exploratory research focused on materials discovery of compounds, such as actinide mixed-oxoanion phases, which exhibit rich structural chemistry. The novel phase K1.8Na1.2[(UO2)BSi4O12] has been synthesized using hydrothermal methods, representing the first example of a uranyl borosilicate. The three-dimensional structure crystallizes in the orthorhombic space group Cmce with lattice parameters a = 15.5471(19) Å, b = 14.3403(17) Å, c = 11.7315(15) Å, and V = 2615.5(6) Å3, and is composed of UO6 octahedra linked by [BSi4O12]5− chains to form a [(UO2)BSi4O12]3− framework. The synthesis method, structure, results of Raman, IR, and X-ray absorption spectroscopy, and thermal stability are discussed.

Cornerstones in Contemporary Inorganic Chemistry

“…Rb 2 KAlF 6 , meanwhile, is a new example of a complex fluoride with the elpasolite structure, essentially a distorted double perovskite with aluminium and potassium occupying the octahedral B sites in a completely ordered arrangement. Solvothermal synthesis was also employed by Zur Loye et al to prepare new solidstate compounds, but on this occasion, more conventionally, the solvent was water [7]. Hydrothermal synthesis leads to K 1.8 Na 1.2 [(UO 2 )BSi 4 O 12 ]-the first reported example of a uranyl borosilicate.…”