Dense Iodoapatite Ceramics Consolidated by Low-Temperature Spark Plasma Sintering

Pb9.85(VO4)6I1.7, a potential waste form for long‐lived I‐129 immobilization, experiences phase decomposition and thus iodine loss at an elevated temperature above 400°C, presenting a significant challenge for effective management of radioactive iodine. In this work, we report low‐temperature consol...

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Bibliographic Details
Published in:Journal of the American Ceramic Society 2015-12, Vol.98 (12), p.3733-3739
Main Authors: Yao, Tiankai, Scott, Spencer, Xin, Guoqing, Lu, Fengyuan, Lian, Jie
Format: Article
Language:English
Subjects:
Alloys
Bulk density
Bulk modulus
Bulk sampling
Ceramics
Consolidation
Decomposition
Fracture toughness
Grain growth
Grain size
Hardness
High temperature
Immobilization
Iodine
Low temperature
Mechanical properties
Microstructure
Modulus of elasticity
Morphology
Nanocrystals
Pellets
Phase decomposition
Plasma sintering
Sintering
Spark plasma sintering
Theoretical density
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Summary:Pb9.85(VO4)6I1.7, a potential waste form for long‐lived I‐129 immobilization, experiences phase decomposition and thus iodine loss at an elevated temperature above 400°C, presenting a significant challenge for effective management of radioactive iodine. In this work, we report low‐temperature consolidation of dense iodoapatite pellets with above 95% theoretical density by spark plasma sintering (SPS) at temperatures as low as 350°C for 20 min without iodine loss. Microstructure analysis indicates a nanocrystalline ceramic with an average grain size less than 100 nm. Grain growth dominates the sintered microstructure at higher temperatures and longer durations. The dense nanoceramics have significantly‐improved fracture toughness as compared with bulk coarsened grain structures. The effects of sintering temperatures (350°C, 400°C, 500°C, and 700°C) and durations (0–20 min) on microstructure, density, fracture morphology, and mechanical properties including Young's modulus and hardness of bulk samples were investigated. Low temperature densified iodoapatites suggest immense potential of SPS as an advanced materials fabrication technology for the development of waste forms for immobilization of volatile radionuclides including radioactive iodine.
ISSN:0002-7820
1551-2916
DOI:10.1111/jace.13867