Self-propagating synthesis of Y2 − xNdxTi2O7 pyrochlore and its aqueous durability as nuclear waste form. (15th March 2018)

• Record Type: Journal Article
• Authors: Zhang, Kuibao; He, Zongsheng; Peng, Le; Zhang, Haibin; Lu, Xirui
• Is Part Of: Scripta materialia. Number 146(2018)
• Page Start: 300
• Page End: 303
• Publication Date: 2018-03-15
• Subjects: SHS -- Pyrochlore -- Phase separation -- Aqueous durability; Materials -- Periodicals; Metallurgy -- Periodicals; Metalen; Legeringen; Materiaalkunde; Metals, metalworking and machinery industries; Metals; Electronic journals; 620.11
• DOI: 10.1016/j.scriptamat.2017.12.020
• Languages: English
• ISSNs: 1359-6462

Abstract

Abstract: Highly densified Nd-bearing Y2 Ti2 O7 pyrochlores were prepared within 5 min by self-propagating high-temperature synthesis plus quick pressing (SHS/QP) using Fe2 O3 as the oxidant. As the surrogate of trivalent actinides, Nd was introduced to substitute the Y site with nominal formulation of Y2 − x Ndx Ti2 O7 . The ordered pyrochlore phase was generated as the main ceramic phase with x ≤ 1.0. Phase separation of Nd-rich and Y-rich phases is formed in the pyrochlore matrix. The pyrochlore-base waste form (Nd0.5 ) demonstrates promising aqueous durability. The 42 days normalized leaching rates of Y and Nd are calculated to be 2.59 × 10 − 5 and 2.80 × 10 − 5 g m − 2 d − 1 . Graphical abstract: Y2 − x Ndx Ti2 O7 /Fe composites were readily prepared within 5 min from SHS/QP process. Ordered Nd-bearing pyrochlore was generated as the main ceramic phase with x ≤ 1.0. The lattice constant and crystal cell volume of pyrochlore phase increase linearly with the increment of x value. The pyrochlore matrix is separated into two substitutional solid solution of Nd-rich and Y-rich phases. The pyrochlore-base waste form demonstrates promising aqueous durability. Image 1