High-Dielectric Polymer Composite Materials from a Series of Mixed-Metal Phenylphosphonates, ATi(C₆H₅PO₃)₃ for Dielectric Energy Storage

We report the preparation of new polymer composite dielectric materials for energy storage applications. New layered 1:1 mixed A+2/Ti4+ metal phenylphosphonates, ATi(O3PC6H5)3, A=Mg, Ca, Sr, Ba, and Pb, have been prepared via a melt route, in which mixed metal oxides, ATiO3, were reacted with molten phenyl phosphonic acid. The mixed-metal phosphonates were combined with polystyrene (PS) via a solution route and cast as thin films for dielectric permittivity measurements. The ATi(O3PC6H5)3-PS composites exhibit a substantial enhancement in the dielectric permittivity as a function of weight loading relative to the parent ATiO3-PS composites. For both ATiO3-PS and ATi(O3PC6H5)3-PS, the composites' dielectric permittivity increases with A cation polarizability. Unusually large increases for 40 wt% ATi(O3PC6H5)3-PS composites (A=Sr, Ba, and Pb) indicate permittivity enhancement that goes beyond the effect of varying filler composition.