Ni-containing spinel aluminates glass-ceramic materials obtained from cordieritic bulk glasses

Monolithic glasses with compositions 2MO · 2Al2O3 · 5SiO2, being M=Ni and equimolar mixtures of Ni and Mg, were prepared at 1650 °C by melting mixtures of raw materials. The crystallization of monoliths was produced by heat-treatment at several temperatures up to 1200 °C. The crystallization sequence was followed by differential thermal analysis (DTA), X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) and diffuse reflectance spectroscopies. Surprisingly, the only crystalline phase formed after heating up to 1100 °C was a nickel-containing aluminate spinel for both compositions. The microstructural characterization indicated the volume crystallization of well formed octahedral crystals of spinel with smaller size than 500 nm. Finally, it has been proved that nickel-containing aluminosilicate glasses could be converted into μ- or α-cordierite- and spinel-based glass-ceramics by thermal treatment of powdered glasses and monolithic bodies, respectively.