Sol‐Gel Coating of Lithium Zinc Ferrite Powders

Lithium zinc ferrite powders of composition Li 0.3 Zn 0.4 Mn 0.05− Fe 2.25 O 4 were prepared by solid—state synthesis. Liquid‐phase borosilicate sintering additives were applied to the ferrite particle surfaces at room temperature via a sol—gel coating technique. Calcined and comminuted ferrite powder was dispersed in methanol with predetermined quantities of tetraethyl orthosilicate and triethyl borate. Hydrofluoric acid was used to catalyze the sol—gel reactions. Amorphous coatings of 10 to 20 nm thickness were observed on particle surfaces by TEM. Chemical bonding in the coatings was studied using diffuse reflectance FTIR spectroscopy.