The onset of thermally induced, heterogeneous structural reorganization of highly radiation-damaged allanite-(Ce) begins at temperatures below 700 K. Three strongly disordered allanite samples (S74 20414: ~ 0.55 wt% ThO2, 22.1 wt% REE oxides, and maximum radiation dose 3.5 × 1018 α-decay/g; LB-1: ~1.18 wt% ThO2, 19.4 wt% REE oxides, and maximum radiation dose 2.0 × 1019 α-decay/g; R1: ~ 1.6 wt% ThO2, 19.7 wt% REE oxides, and maximum radiation dose 2.6 × 1018 α-decay/g) were step-wise annealed to 1000 K in air. Using orientation-dependent nanoindentation, synchrotron single-crystal X-ray diffraction (synchrotron XRD), X-ray powder diffraction (powder XRD), differential scanning calorimetry and thermogravimetric analysis (DSC/TG), mass spectrometry (MS), 57Fe Mössbauer spectroscopy and high-resolution transmission electron microscopy (HRTEM), a comprehensive understanding of the structural processes involved in the annealing was obtained. As a result of the overall increasing structural order, a general increase of hardness (pristine samples: 8.2–9.3 GPa, after annealing at 1000 K: 10.2–12 GPa) and elastic modulus (pristine samples: 115–127 GPa, after annealing at 1000 K: 126–137 GPa) occurred. The initially heterogeneous recrystallization process is accompanied by oxidation of iron, the related loss of hydrogen and induced stress fields in the bulk material, which cause internal and surface cracking after step-wise annealing from 800 to 1000 K. HRTEM imaging of the pristine material shows preserved nanometer-sized crystalline domains embedded in the amorphous matrix, despite the high degree of structural damage. The results show that hardness and elastic modulus are sensitive indicators for the structural reorganization process.

中文翻译：

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辐射损伤的铝榴石-(Ce) 的机械和结构特性以及热退火的影响

受高度辐射损伤的花岗岩 (Ce) 的热诱导、异质结构重组开始于 700 K 以下的温度。 三个强烈无序的花岗岩样品（S74 20414：~ 0.55 wt% ThO2、22.1 wt% REE 氧化物和最大辐射剂量 3.5 × 1018 α-衰变/g；LB-1：~1.18 wt% ThO2，19.4 wt% REE 氧化物，最大辐射剂量 2.0 × 1019 α-衰变/g；R1：~ 1.6 wt% ThO2，19.7 wt% REE 氧化物和最大辐射剂量 2.6 × 1018 α-衰变/g）在空气中逐步退火至 1000 K。使用取向相关纳米压痕、同步加速器单晶 X 射线衍射（同步加速器 XRD）、X 射线粉末衍射（粉末 XRD）、差示扫描量热法和热重分析（DSC/TG）、质谱法（MS）、57Fe 穆斯堡尔谱和高分辨率透射电子显微镜（HRTEM），获得了对涉及退火的结构过程的全面了解。由于整体结构顺序增加，硬度（原始样品：8.2-9.3 GPa，在 1000 K 退火后：10.2-12 GPa）和弹性模量（原始样品：115-127 GPa，在1000 K：126–137 GPa) 发生。最初的异质再结晶过程伴随着铁的氧化、相关的氢损失和大块材料中的诱导应力场，在 800 到 1000 K 的逐步退火后导致内部和表面开裂。原始材料的 HRTEM 成像显示尽管存在高度的结构损坏，但仍保留了嵌入在非晶基质中的纳米尺寸的结晶域。