Study of the effect of Ca/Mg alkali-oxides ratio on the structure of a glass-ceramic based on an aluminosilicated glass containing 2wt.% of zirconolite crystalline phase

Abstract

New nuclear glass-ceramics are extensively studied for the radioactive waste confinement, due to the double confinement conferred by the glass-ceramics. In this study, a glass-ceramic constituted by an aluminosilicate glass in the system: SiO2-Al2O3-CaO-MgOZrO2-TiO2, containing 2wt.% of Ca0.83Ce0.17ZrTi1.66Al0.34O7 zirconolite, has been synthesized by the discontinuous method. Cerium, an actinide surrogate is introduced both in the glass and ceramic phases. The synthesis is performed by a double melting at 1350?C, followed by a nucleation at 564?C, during 2 h, and a crystal growth at 1010?C during 3 h. Then effect of Ca/Mg ratio on the distribution of the crystalline network in the material was studied for Ca / Mg ratios ranging from 0.4 to 5.5. For the whole of the materials, Archimedes density is about 2.80 g/cm3. X-ray diffraction (XRD) analysis shows that the increase of Ca/Mg ratio leads to the increase of aluminosilicated crystalline phases with high Ca contents; the materials molar volumes remaining constant. The zirconolite phase is not affected by these additive aluminosilicated phases. The scanning electron microscopy analysis (SEM) coupled with energy dispersive X-ray (EDX) analysis confirmed these results; and shows the uniformity of distribution of the ceramics in the bulk of the materials.

Study of The Effect of TiO2 Addition On The Crystalline Phases, Structure and Chemical Durability of a Nuclear Glass Ceramic

“…The GC chemical compositions are inspired from previous research studies [17,18]. The samples are prepared with the following TiO2 contents: 4.11, 5.11, 6.11 and 7.11wt.…”

Removal of Cs ions from aqueous solutions by using matrices of natural clinoptilolite and its safe disposal

“…Therefore, it is of significant importance to remove and safely dispose radioactive Cs from the waste streams. A multitude of storage materials have been studied, among which glasses, minerals, and glass-ceramic matrices [2,3]. One of the most effective procedures consists of two steps: (1) removal of Cs cations by ion exchange and (2) suitable solidification treatment [4,5].…”

Structure and Thermal Expansion of Calcium–Thorium Apatite, [Ca4]F[Ca2Th4]T[(SiO4)6]O2

“…In the present context, this compositional variety, together with high chemical durability over a wide range of pH and temperature, makes apatite matrices suitable for the immobilization of fission products and transuranic radionuclides. Moreover, unlike other actinide–lanthanide fixation ceramics based on zirconolite, − perovskite, or titanite, the apatites uniquely can accommodate radioactive iodine. − …”