Thermal decomposition of crystalline Ni(II)-Cr(III) layered double hydroxide: a structural study of the segregation process.
A structural study of the thermal evolution of Ni(0.69)Cr(0.31)(OH)(2)(CO(3))(0.155) x nH(2)O into NiO and tetragonal NiCr(2)O(4) 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.
Sileo
Elsa E
EE
INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón II, Ciudad Universitaria, C1428EHA - Buenos Aires, Argentina. sileo@qi.fcen.uba.ar
Jobbagy
Matías
M
Paiva-Santos
Carlos O
CO
Regazzoni
Alberto E
AE