Effect of improved trialkyl phosphine oxides waste content on phase composition and density of spark plasma sintered Gd ₂ Zr ₂ O ₇ ceramics

Abstract

As a rapid sintering method, spark plasma sintering (SPS) process has been widely applied to immobilize nuclear waste. In this work, trialkyl phosphine oxides (TRPO) were immobilized by the mixture of Gd 2 O 3 and ZrO 2 with SPS proceedings at 1650 C in 3 minutes. X-ray diffraction results present that the solid solubility is 10 to 20 wt% and all the sintered samples show a fluorite structure. Raman spectroscopy results show that the order degree of structure decreases as waste content increases. The lattice parameters decrease with the increasing doped waste content indicating the success of waste immobilization. Densities decrease for the sample with higher waste content which mainly caused by the existence of pores. Scanning electron microscope-energy dispersive X-ray spectroscopy and backscattered electron results perform the microstructure of the sintered sample. Furthermore, the leaching test shows that the sample has a considerable chemical stability. This study confirmed the possibility of rapid consolidation of Gd 2 Zr 2 O 7 bulk, dense ceramic with up to 10~20 wt% of immobilized TRPO waste. Highlights• Multi-nuclides waste was rapidly immobilized by Gd 2 Zr 2 O 7 via SPS process.• Phase transition happened with enhanced doping content.• Density results decreased with the higher waste content.• The order degree of structure decreased as waste content increased.• The sintered matrix represented considerable chemical stability. K E Y W O R D S ceramic, Gd 2 Zr 2 O 7 , immobilization, SPS, TRPO waste Ningning He and Guilin Wei contributed equally to this work.

Perovskite/Pyrochlore Composite Mineral-like Ceramic Fabrication for 90Sr/90Y Immobilization Using SPS-RS Technique

“…SPS is based on heating the compact through pulsed electric current under uniaxial pressing conditions, with high heating rates and short processing times measured in minutes. In particular, the potential of SPS has been experimentally demonstrated for synthesizing pyrochlore structure ceramic [26], scheelite [27][28][29], feldspar-like [30], sodium zirconium phosphate (NZP) [31], and glass-ceramic composites for immobilizing 90 Sr [32][33][34][35][36]. Additionally, our work has initially demonstrated high promise for applying SPS to produce a mineral-like SrTiO 3 perovskite matrix for 90 Sr immobilization, as well as to fabricate a prototype of IRS based on this approach [37].…”