Co2Z ferrite powders with the chemical composition 3Ba0.5Sr0.5O2CoO12Fe2O3 have superior high frequency magnetic properties. However, Co2Z ferrite powders are difficult to apply to practical processes because of agglomeration induced by the strong magnetic attraction between particles. In this study, Co2Z ferrite powders pretreatment using a titanate coupling agent ‐ neopentyl(dially)oxy tri(dioctyl)pyrophosphate titanate (Lica 38) on the sedimentation and rheological behavior is investigated. The bonding mechanisms between ferrite powder, Lica 38, and poly(vinyl butyral) (PVB) are studied using diffuse reflectance Fourier transform infrared spectroscopy is used to explain the difference in the rheological and sedimentation behaviors of untreated and titanate coupling agent-modified ferrite powders. The affinity of Co2Z ferrite and PVB could be substantially enhanced by coating a titanate coupling agent onto the ferrite surface. The coated layer could prevent particles from agglomeration induced by the magnetic interaction. # 2004 Published by Elsevier B.V.