Characterization of the Microstructure of Zirconolite-Based Glass-Ceramics

TL;DR

This paper investigates the microstructure evolution of zirconolite-based glass-ceramics, focusing on how thermal treatment temperature affects crystallization, using SEM and XRD analysis, relevant for nuclear waste immobilization.

Contribution

It provides detailed analysis of zirconolite crystallization in glass-ceramics across a temperature range, aiding nuclear waste management strategies.

Findings

Crystallization varies with temperature from 950°C to 1350°C.

SEM and XRD reveal microstructural changes during thermal treatment.

Optimal crystallization conditions identified for waste immobilization.

Abstract

December 1991 legislation in France has spurred research on enhanced separation and conditioning or transmutation of long-lived radionuclides from high level radioactive wastes (HLW). In this field, we have studied zirconolite-based glass-ceramics in which the crystalline phase (zirconolite: CaZrTi2O7) aimed to preferentially incorporate minor actinides is embedded in a glassy calcium aluminosilicate matrix. At the laboratory scale, the crystallization of the parent glass is carried out thanks to a two-step thermal treatment: a nucleation stage followed by a growth stage. This paper presents the evolution of the crystallization, followed by scanning electron microscopy (SEM) and X-ray diffraction (XRD), with the temperature of the crystal growth thermal treatment, in the range 950 degrees - 1350 degrees C.