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Radiophase Development in Hot‐Pressed Alkoxide‐Derived Titanate Ceramics for Nuclear Waste Stabilization
Author(s) -
Dickson Fiona J.,
Mitamura Hisayoshi,
White Timothy J.
Publication year - 1989
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1989.tb06270.x
Subject(s) - materials science , hot pressing , hollandite , ceramic , pyrochlore , microstructure , rutile , phase (matter) , titanate , alkoxide , metallurgy , perovskite (structure) , zirconolite , mineralogy , chemical engineering , chemistry , crystallography , biochemistry , organic chemistry , engineering , catalysis
Phase development as a function of hot‐pressing temperature was studied in alkoxide‐derived titanate‐based ceramics doped with a 10 wt% loading of a sodium‐rich (NAR) and a sodiumpoor (NAP) simulated high‐level waste. Pyrochlore was found to be the most abundant phase in both calcine powders. A pseudobrookite phase existed metastably at hot‐pressing temperatures between 890° and 920°C. After hot‐pressing at 1100°C, the final phase assemblage for the NAP material consisted of zirconolite, hollandite‐type, perovskite, alloy, and reduced rutile (Magnéli phases). In addition, NAR samples contained hibonite, freudenbergite, and loveringite. Phase development was driven to completion over a very narrow temperature range (50°C), beginning at 870° and 850°C for NAP and NAR, respectively, although full densification was not achieved below 1100°C. Both waste forms exhibited comparable microstructure and aqueous durability.