The incorporation of Nd or Ce in CaZrTi2O7 zirconolite: ceramic versus glass-ceramic

Abstract

Three sets of the zirconolite ceramic and glass-ceramic systems have been investigated including Ca1−xZr1−xNd2xTi2O7, Ca1−xNdxZrTi2-xAlxO7 and CaZr1−xCexTi2O7 (x = 0 − 0.5). The zirconolite formation is compared between ceramics sintered at 1300 °C for 12 h and glass-ceramics sintered at 1250 °C for 3 h. Powder X-ray diffraction, Raman and scanning electron microscopy techniques are used to analyze the crystal structure, morphologies and composition distribution. Ca1−xNdxZrTi2-xAlxO7 can incorporate 0.5 formula unit of Nd in dominant zirconolite in both ceramic and glass-ceramic samples with baddeleyite as minor phase and slight amount of sphene in glass-ceramics, with more than 86% of the Nd initially introduced staying in zirconolite phase. Less Nd can be doped in zirconolite dominated Ca1−xZr1−xNd2xTi2O7 system with perovskite as a minor phase in ceramics and sphene as a minor phase in glass-ceramics. Only small amounts of Ce (x ≤ 0.1) can be incorporated in CaZr1−xCexTi2O7 zirconolite ceramic and glass-ceramics without obvious minor phases. © 2020 Published by Elsevier B.V. All rights reserved.