Spectroscopic studies of transition-metal oxides, silicates, and pnictides: developing materials capable of sequestering nunclear waste

由于环境问题，各国政府正在考虑逐步淘汰化石燃料发电机，核能再次成为一个重要的替代能源。虽然核反应堆产生的电力是“清洁的”，但却产生了危险的放射性废物。加拿大提供了世界上25%的铀（产值25亿美元），其中大部分用于核电设施。为了提高加拿大在美国市场的地位，开发用于储存核废料的材料是很重要的。这些废物可以被隔离在密集堆积的化合物中，从而延缓放射性元素的向外扩散。这项研究计划的长期目标是开发有序的化合物，可以在结构中隔离U并抵抗辐射引起的结构损伤。为了启动这项研究，将对代表主体材料的模型化合物进行研究，以便清楚地了解晶体结构、组成、成键、电子结构和表面对铀等锕系元素的反应性之间的关系。在这个项目中，焦绿石陶瓷(A2B2X6X'; a =Ca, Mn, Fe，稀土（RE）；B =钛、Nb、助教;X/X′=O， F， OH)，采用锆石（ASiO4； A=Zr, Hf）和锆石（A2B2O7; A/B=Ca， V, Zr, Ti, Hf）结构的材料，无定形硅酸盐（[AO2] X [A' o2]y[SiO2]1-x-y; A/A′=Ti, Zr, Hf）和角长石（REM4Pn12； RE=La, Ce, Eu, Gd; M = Fe, Co; Pn (pnictide)=P, As, Sb, Bi）。利用同步辐射，利用x射线衍射、x射线光电子能谱和x射线吸收能谱来研究这些材料的电子结构和氧化能力。研究晶态和非晶态硅酸盐将允许研究辐射引起的结构损伤如何影响材料隔离u的能力（上述许多材料也应用于半导体设备，发电和制冷）。本研究项目致力于应用x射线光谱学研究上述体系元素取代后的氧化行为和电子结构变化，从而开发出能够封存核废料的材料。

With governments considering phasing out fossil fuel based power generators because of environmental concerns, nuclear energy is once again a serious alternative. Although the power generated by nuclear reactors is "clean", hazardous radioactive waste is produced. Canada supplies >25% of the worlds' uranium (U) supply (production value >$2.5 billion), with much of it destined for nuclear power facilities. To increase Canada's position in the U market, it is important to develop materials for use in the storage of nuclear waste. This waste can be sequestered in compounds that are densely packed and retard outward diffusion of the radioactive elements. The long-term goal of this research program is the development of ordered compounds that can sequester U in the structure and resist radiation induced structure damage. To initiate this research, model compounds representing host materials will be examined in order to gain a clear understanding of the relationship between crystal structure composition, bonding, electronic structure, and surface reactivity to the sequestration of actinides like U. In this program, pyrochlore ceramics (A2B2X6X'; A=Ca, Mn, Fe, rare-earths (RE); B=Ti,Nb,Ta; X/X'=O, F, OH), materials adopting the zircon (ASiO4; A=Zr, Hf) and zirconolite (A2B2O7; A/B=Ca, V, Zr, Ti, Hf) structures, amorphous silicates ([AO2]x[A'O2]y[SiO2]1-x-y; A/A'=Ti, Zr, Hf), and skutterudites (REM4Pn12; RE=La, Ce, Eu, Gd; M = Fe, Co; Pn (pnictide)=P, As, Sb, Bi) will be synthesized. The electronic structure and ability of these materials to be oxidized will be investigated by X-ray diffraction, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy, utilizing synchrotron radiation. Studying crystalline and amorphous silicates will allow for an examination of how radiation induced structure damage affects a materials ability to sequester U. (Many of the above materials also have applications in semiconductor devices, power generation, and refrigeration.) This research program is dedicated to applying X-ray spectroscopy to the study of the oxidation behaviour and changes in electronic structure with elemental substitution of the systems described above, so as to develop materials capable of sequestering nuclear waste.