Chemistry Weekly Seminar - Dr. Andrew Grosvenor, University of Saskatchewan

Title

The unexpected consequences of synthesizing solid-state materials at low temperatures

Abstract

Multiple oxide materials have been proposed for the sequestration of high-level nuclear waste owing to the ability of these structures to incorporate a range of actinide elements and fission products. Oxides adopting the pyrochlore-, zirconolite-, hollandite-, and garnet-type structures have been investigated for several years for nuclear waste sequestration applications. The ceramic method is a common method used to synthesize these materials; however, this method often requires the use of high annealing temperatures and long reaction times. The synthesis of nuclear waste form materials on the industrial scale needs to be cost-effective, able to be performed on large scales, and allow for the incorporation of waste elements that are in either liquid or solid phases. Solution based synthesis methods (e.g., sol-gel and coprecipitation) are desirable to produce these materials owing to the lower annealing temperatures and reduced reaction times that can often be used to produce these materials as a result of the intimate mixing of the reactants. The focus of the first part of this presentation will be on our recent studies of how low-temperature synthesis methods can be used to form zirconolite- (CaZrTi₂O₇) type oxides as well as the effect of annealing temperature on the oxidation state of Ce in garnet- (Y_3-zCe_zAlFe₄O₁₂) and pyrochlore- (Gd_2-xCe_xTi₂O₇) type oxides. The second part of this presentation will focus on our recent studies on synthesizing glass-ceramic composite materials containing rare-earth phosphates dispersed in a borosilicate glass matrix. It has been found that the glass composition can play a significant role in synthesizing these materials at low temperatures.

Date:       Friday, March 12, 2021

Time:      1:30 p.m.

Via Zoom video conference (link available by request to chem.dept@usask.ca)