Phase evolution and chemical durability of co-doped Gd2Zr2O7 ceramics for nuclear waste forms

ZHANG²,

Deng

et al. 2020

Preprint

In this work, Nd3+ was used as a surrogate and it was incorporated into Gd2Zr2O7 nanocrystalline ceramics to simulate the immobilization of trivalent actinide elements. A series of Gd2 − xNdxZr2O7 (0.0 ≤ x ≤ 2.0) nanocrystalline powders were fabricated by solvothermal method, and then Gd2 − xNdxZr2O7 sub-microncrystalline ceramics were prepared by sintering via self-propagating chemical furnace plus quick pressing (SCF/QP). All powders are in defective fluorite structure, and Nd doping hardly change the powder grain size. After analyzing the sintered ceramics, it can be found that the transition from defective fluorite structure to pyrochlore structure occurs when x ≥ 1.5. The sample density decreases with elevated Nd content, while the grain size gradually enlarges. Besides, the normalized release rates of Nd and Zr elements in the Nd2Zr2O7 waste form are kept in low values (below 10− 5 g•m− 2•d− 1), which exhibits its excellent aqueous stability.

Section: Aqueous Durability Analysis Of Nd 2 Zr 2 O 7 Ceramiccontrasting

confidence: 57%

Section: Introductionmentioning

confidence: 99%

Rapid Synthesis and Chemical Durability of Gd2- x Nd x Zr2O7 (0.0 ≤ x ≤ 2.0) Sub-Micron Ceramics as Nuclear Waste Forms

ZHANG²,

Deng

et al. 2020

Preprint

“…The normalized leaching rate of elements depends on the bond energy of their binding to oxygen atoms. 58,59 There is a negative correlation between the bond energy and bond length. In this study, the XPS results showed that there was a coexistence of Ce 3+ and Ce 4+ in the samples.…”

Section: Chemical Durabilitymentioning

confidence: 99%

The solubility, microstructure, and chemical durability of Ce‐doped YIG ceramics designed as actinide waste forms

Luo

et al. 2021

Int J Energy Res

Self Cite

Yttrium iron garnet (YIG) is a potential matrix for immobilizing high-level radioactive waste (HLW) due to its high actinide solubility and chemical flexibility. In this study, Ce was employed as a surrogate of Pu. A series of Y 3-x Ce x Fe 5 O 12 (0 ≤ x ≤ 1) samples were prepared by solid-state sintering at 1400 C to investigate the solubility, microstructure, and chemical durability of Ce-doped YIG. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) results showed that the solubility of the Ce in a single garnet was 32 mol% at synthesis temperature of 1400 C. The SEM analysis indicated the

“…Those properties are attributable to the pyrochlore crystal structures that is a superstructure derivative of the simple uorite. As such, La 2 Zr 2 O 7 has attracted signi cant interest in various applications, such as high temperature ceramic thermal barrier coating materials, photocatalysts, solid electrolytes, nuclear waste containers, host materials for luminescence centers and so on [7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of novel porous La2Zr2O7 ceramic with ultralow thermal conductivity and excellent photocatalytic property

Geng³

et al. 2021

Preprint

A novel porous La2Zr2O7 ceramic prepared by combining a sol-gel template method and high-temperature calcination process. The structural evolution and crystallisation behaviour of the samples were systematically characterized using SEM, XRD, TEM and Raman spectroscopy. The results indicated that the as-prepared porous La2Zr2O7 ceramic had a typical nanoparticles assembling and mesoporous structure with single-phase pyrochlore crystal structure. Meanwhile, the as-prepared porous La2Zr2O7 ceramic presented an ultralow room temperature thermal conductivity of 0.07 W/(m·K), high specific surface areas of 325.17 m2/g and a relatively high compressive strength of 11.95 MPa. What’s more, the as-prepared porous La2Zr2O7 ceramic possessed ideal photocatalytic activity owing to the unique 3-D porous structure, high crystallinity and large surface area. These reported studies are proposing some new insight to improve porous rare-earth zirconates ceramic for thermal insulation and dye degradation applications.