Crystallization and microstructural development of nickel-containing aluminosilicate glasses with cordierite stoichiometry

The crystallization behaviour of two glasses with chemical compositions MAl2O4/SiO2=1/2.5, being MNi and equimolar mixtures of Mg and Ni, was investigated. Glasses were prepared by cooling samples melted at 1650 °C. During thermal treatment over the range of temperature up to 1200 °C both glasses were first crystallized to form a β-quartz solid solution, then transformed to α-cordierite or spinel depending on the amount of nickel. The temperatures of both the crystallization of β-quartz solid solution and its further transformation were also dependent on the nominal amount of nickel. Lower temperatures were found for glasses with a large amount of nickel. UV–Vis diffuse reflectance characterization of the starting and thermal treated glasses indicated that the Ni+2 cations located in tetrahedral sites in the glass moved into octahedral sites after forming the final crystalline phases. The microstructural features of α-cordierite-based material from nickel–magnesium cordierite glasses heated at 1100 °C, examined by field emission scanning electron microscopy (FESEM) revealed the formation of well-defined crystals including regular and elongated hexagonal shaped prisms and square shaped particles.