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Many glass ceramics are potential candidates for the confinement of radioactive waste. This is the case of glasses embedding radiation-resistant ceramics as zirconolites, pyrochlores or pyroxenes. This study deals with the influence of the crystal growth temperature on the formation of such phases in a nuclear glass ceramic in the system: Al 2 O 3 -SiO 2 -CaO-MgO-ZrO 2 -TiO 2 . The materials with six contents of ZrO 2 , ranging from 1.00 to 6.40 m.%, are synthesized by a discontinuous method, consisting in a double-melting at 1,350 °C, followed by both a nucleation at 564 °C, and a crystal growth treatment at: 900, 100 and 1,100 °C. For the whole of the materials, the morphology reveals a glassy feature, with a opaque aspect. One can also evidence a different crystallization process from the bulk to the surface. The glass ceramics X-ray diffraction analysis (XRD) show that the main identified crystalline skeletons are those of: 2M-zirconolite, CaZrTi 2 O 7 and ZrO 2 , depending on the content of ZrO 2 in materials and the crystal-growth temperature. The material with the middle content in ZrO 2 (4.5 m.%) and crystallized at the middle value of Tc (1,010 °C) show the greatest content in zirconolite (87 %), doped with either lanthanides or alcalin-earth elements, due to the complexity of the mixture of oxides. The temperature of 1,010 ° C appears to be more selective with regard to the formation of the 2M-zirconolite.

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