XANES studies on disorder-order transition that occurs in a nanosized spinel ZnFe2O4

FIGUEROA, S. J. A.; S. G. MARCHETTI; J. F. BENGOA; R. J. PRADO; J. M. RAMALLO-LÓPEZ; F. G. REQUEJO; S. J. STEWART

Simposio; 20th Anniversary of the Hercules programmeXX Symposium; 2010

ESRF

The non-equilibrium cation site occupancy in nanosized zinc ferrites(6-13nm)with different degree of  inversion (0.2 to 0.4) was investigated using Fe and Zn K-edge x-ray absorption spectroscopy. Experimentally we find a direct correlation between the Zn K-edge XANES features and the inversion of the spinel. We propose a simple model of transference between octahedral [B] and tetrahedral (A) sites and with this model is possible match the general behavior of the inversion by XANES simulations at Zn-Kedge. This explains our experimental results and allows us to investigate the thermal evolution of the non-equilibrium state in nano-sizedZnFe2O4 by using the factor analysis approach. Isothermal treatments confirm that the Zn transference follows a first-order kinetic process. In addition, the thermal treatment produces a partial recrystallization that increases the average grain size from 13 to 50 nm and reduces the microstrain.