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首页> 外文会议>Materials Research Society Symposium >Identifying and Quantifying Actinide Radiation Damage in Ceramics with Radiological Magic-Angle Spinning Nuclear Magnetic Resonance
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Identifying and Quantifying Actinide Radiation Damage in Ceramics with Radiological Magic-Angle Spinning Nuclear Magnetic Resonance

机译：用放射魔法角旋转核磁共振识别和定量陶瓷陶瓷辐射损伤

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In the characterisation of amorphisation or local disordering due to actinide radiation damage, nuclear magnetic resonance (NMR) spectroscopy is attractive because it is element specific and equally sensitive to local structure in crystalline and amorphous materials. Here, we have applied high-resolution solid-state NMR spectroscopy (magic-angle spinning) to radiation damaged natural minerals containing 238~U/232~ Th to determine the 'number fraction' of amorphous material (f_a) through spin-counting techniques. In samples with a known alpha dose, the number of atoms displaced per alpha decay may be determined from an integration of the spectrum. A protocol for performing similar radiological magic-angle spinning experiments on plutonium containing ceramic samples with an activity of > 5 GBq is described. Results obtained have allowed data from ancient, radiation damaged mineral samples of ZrSi0_4 ( U/ Th) to be compared with modern (238/239)~Pu doped ceramic ZrSi04 samples. The number of atomic displacements per alpha particle from (239)~Pu is similar to that for 238~U/232~Th (4980 ± 300/alpha). At lower a-doses there are significant differences in the amorphous volume fraction (observed by density and x-ray diffraction) and the number fraction of displaced atoms (as measured by NMR) as a function of cumulative dose. These differences arise from local density considerations that manifest themselves in the local structure of the amorphous and crystalline phases. Using ab initio simulations of the damaged crystalline and amorphous regions, the magnetic response of these structures and hence the NMR shifts can be compared with experiment to reveal the nature of radiation induced changes occurring at the local scale.
机译：在非恒碱化辐射损伤引起的无晶体或局部失调的表征中，核磁共振（NMR）光谱是具有吸引力的，因为它是对晶体和非晶材料的局部结构特异性和同样敏感的。在此，我们已经应用了高分辨率固态NMR光谱（魔法角旋转）到含有238〜U / 232〜Th的辐射损坏的天然矿物，以通过自旋计数技术确定非晶材料（F_A）的“数量分数” 。在具有已知α剂量的样品中，可以根据光谱的集成确定每个α衰减的原子数。描述了用于对含有> 5GBQ活性的含有> 5GBQ的含陶瓷样品进行类似放射魔法角纺纱实验的方案。获得的结果允许来自古代，辐射损坏ZrSIO_4（U / T）的矿物样品与现代（238/239）〜PU掺杂陶瓷ZrSI04样品进行比较。来自（239）〜PU的每个α粒子的原子位移数与238〜U / 232〜th（4980±300 / alpha）类似。在较低的a剂量下，无定形体积分数（由密度和X射线衍射观察）的显着差异，并且作为累积剂量的函数，偏移原子的数量分数（如NMR测量）。这些差异因局部密度考虑而出现，所述局部密度考虑在无定形和结晶相的局部结构中表现出来。使用损坏的晶体和非晶区域的AB初始模拟，可以将这些结构的磁响应与实验进行比较，以揭示在局部等级上发生的辐射诱导变化的性质。

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