Crystal structure and microstructure of synthetic hexagonal magnesium-cobalt cordierite solid solutions (Mg(2-2x)Co(2x)Al4Si5O18).
Acta Crystallogr B Struct Sci Cryst Eng Mater
; 69(Pt 2): 110-21, 2013 Apr.
Article
en En
| MEDLINE
| ID: mdl-23719698
ABSTRACT
Co(2+)-containing cordierite glasses, of nominal compositions (Mg(1-x)Co(x))2Al4Si5O18 (with x = 0, 0.2, 0.4, 0.6, 0.8 and 1), were prepared by melting colloidal gel precursors. After isothermal heating at 1273 K for around 28 h, a single-phase α-cordierite (high-temperature hexagonal polymorph) was synthesized. All materials were investigated using X-ray powder diffraction and field-emission scanning electron microscopy. The crystal structure and microstructure were determined from X-ray diffraction patterns. Rietveld refinement confirmed the formation of magnesium-cobalt cordierite solid solutions. The unit-cell volume increased with the increase of cobalt content in the starting glass. The crystalline microstructure of the cordierites was interpreted using a mathematical model of a polycrystalline material and characterized by prevalent crystallite shape, volume-weighted crystallite size distribution and second-order crystalline lattice-strain distribution. Hexagonal prismatic was the prevalent shape of α-cordierite crystallites. Bimodality in the size distribution was observed and interpreted as a consequence of two paths of the crystallization the nucleation from glass of µ-cordierite, which transformed into α-cordierite with annealing, or the nucleation of α-cordierite directly from glass at high temperatures. Scanning electron microscopy images agreed well with crystalline microstructure characteristics determined from the X-ray diffraction line-profile analysis.
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1
Colección:
01-internacional
Base de datos:
MEDLINE
Tipo de estudio:
Prognostic_studies
Idioma:
En
Revista:
Acta Crystallogr B Struct Sci Cryst Eng Mater
Año:
2013
Tipo del documento:
Article
País de afiliación:
España