Artículos de revistas
Thermal decomposition of crystalline Ni-II-Cr-III layered double hydroxide: A structural study of the segregation process
Fecha
2005-05-26Registro en:
Journal of Physical Chemistry B. Washington: Amer Chemical Soc, v. 109, n. 20, p. 10137-10141, 2005.
1520-6106
10.1021/jp050639v
WOS:000229296600039
Autor
Univ Buenos Aires
Universidade Estadual Paulista (Unesp)
Comis Nacl Energia Atom
Institución
Resumen
A structural study of the thermal evolution of Ni0.69Cr0.31(OH)(2)(CO3)(0.155)(.)nH(2)O into NiO and tetragonal NiCr2O4 is reported. The characteristic structural parameters of the two coexisting crystalline phases, as well as their relative abundance, were determined by Rietveld refinement of powder x-ray diffraction (PXRD) patterns. The results of the simulations allowed us to elucidate the mechanism of the demixing process of the oxides. It is demonstrated that nucleation of a metastable nickel chromite within the common oxygen framework of the parent Cr-III-doped bunsenite is the initial step of the cationic redistribution. The role that trivalent cations play in the segregation of crystalline spinels is also discussed.