DIFFUSION, SEGREGATION AND DESORPTION OF POTASSIUM FROM K2Fe22O34 FERRITE

Abstract

The samples of K 2 Fe 22 O 34 phase were synthesized and characterized by XRD, BET, SEM-EDX and XPS. K+ diffusion was investigated by impedance spectroscopy, whereas the surface segregation and desorption were monitored by Kelvin Probe (changes in work function) and Species Resolved Thermal Alkali Desorption, at the temperature range of 600–1000 K. The analysis of changes in work function and desorption signals ( K and K+ ) at various temperatures allowed to resolve the kinetic parameters (flux, rate constants, activation energies) of potassium diffusion, surface accumulation and desorption. Based on the obtained results, the simple, functional model of bulk and surface changes of K -β-ferrite was proposed.