Disordered microporous Sandia octahedral molecular sieves are tolerant to neutron radiation†

Abstract

Materials that possess a porous and defected structure can have a range of useful properties that are sought after, which include their tolerance to nuclear radiation, ability to efficiently store and release isotopes, immobilize nuclear waste, and exhibit phase stability even at elevated temperatures. Since nanoscale pores and surface structures can serve as sinks for radiation-induced amorphization, one-dimensional (1D) porous nanorods, due to their high surface-to-volume ratio, have the potential for use as advanced materials in nuclear science applications. In this study, we demonstrate a synthesis and a detailed analysis of microporous 1D octahedral molecular sieves of disodium diniobate hydrate [(Na₂Nb₂O₆·H₂O) or Sandia octahedral molecular sieves (SOMS)]. In addition, the stability of these SOMS is evaluated following their exposure to elevated temperatures and neutron irradiation. A solvothermal method is used to prepare these SOMS-based nanorods. This relatively low temperature, solution-phase approach can form crystalline nanorods of microporous Na₂Nb₂O₆·H₂O. These 1D structures had an average diameter of ∼50 nm and lengths >1 μm. The nanorods adopted a defected microporous phase and matched the C2/c space group, which also exhibited resistance to radiation-induced amorphization. The dimensions, phase, and crystallinity of the SOMS-based nanorods after exposure to a high incident flux of neutrons were comparable to those of the as-synthesized products. The radiation tolerance of these microporous SOMS could be useful in the design of materials for nuclear reactors, resilient nuclear fuels, thermally resilient materials, high temperature catalysts, and durable materials for the handling and storage of radioactive waste.