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Evolution of the Ni 2+ Environment During the Formation of a MgO – Al 2 O 3 – SiO 2 Glass‐Ceramic: A Combined XRD and Diffuse Reflectance Spectroscopy Approach
Author(s) -
Dugué Aymeric,
Cormier Laurent,
Dargaud Olivier,
Galoisy Laurence,
Calas Georges
Publication year - 2012
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2012.05421.x
Subject(s) - spinel , crystallization , materials science , rietveld refinement , octahedron , phase (matter) , non blocking i/o , mineralogy , analytical chemistry (journal) , nickel , crystallography , crystal structure , metallurgy , chemical engineering , chemistry , chromatography , organic chemistry , biochemistry , engineering , catalysis
The effect of the addition of NiO on the crystallization mechanisms has been studied for SiO 2 – Al 2 O 3 – MgO glass‐ceramics. A detailed Rietveld analysis has been made to determine the chemical composition and the cation distribution in the spinel phase and the evolution of Ni 2+ coordination site using diffuse reflectance spectroscopy. Powder X ‐ray diffraction ( XRD ) results show the formation of β‐quartz and spinel and the nickel fraction in the spinel phase decreasing as the plateau temperature increases. The determination of cation distribution in spinel using XRD reveals a preference of Ni 2+ and Al 3+ for octahedral sites and an increasing proportion of Ni 2+ in tetrahedral sites for heat treatments at high temperature (1100°C–1200°C). Diffuse reflectance spectroscopy shows that Ni 2+ is mainly fivefold coordinated in the starting glass, playing an important role in the crystallization of the spinel phase and it confirms the presence of tetrahedral and octahedral Ni 2+ in the glass‐ceramics. The combination of these two techniques also indicates a chemical heterogeneity of spinel crystals with Ni 2+ ‐rich and Mg 2+ ‐rich zones.