Preparation And Energy Storage Characteristics Of (1-x)Pb(Mg_1/3Nb_2/3)O₃-xPbTiO₃ Based Thin Film Capacitor

In recent years,thin-film dielectric capacitors have attracted more and more attention because of their small size and light weight.Ferroelectric film capacitor plays an important role with superior performance due to their large maximum polarization and high dielectric breakdown,excellent thermal stability and fatigue performance.Among them,relaxor ferroelectric thin-film capacitors are an important part because of their lower remanent polarization,leading to high energy density(W_rec)and efficiency（η）.（1-x）Pb(Mg_1/3Nb_2/3)O₃-x PbTiO₃（PMN-PT）is a classical relaxor ferroelectric material,but there are very few studies on its energy storage performance.We believe that it has great energy storage potential.In this work,by changing the stoichiometric ratio,thickness and substrate of PMN-Pt,we selected the optimal PMN-Pt film,93PMN-7PT on SrTiO₃（STO）substrate.Then,we study the effects of buffer layer on energy storage properties of relaxor 93PMN-7PT thin-film capacitors with 5 nm-thick STO and La Al O₃（LAO）films.The energy storage properties of Pt/PMN-PT/Sr Ru O₃（SRO）capacitors are found to be significantly changed by buffering the STO or LAO layer at the top Pt/PMN-PT interface while inserting the dielectric layer at bottom PMN-PT/SRO interface shows negligible effects on the electrical properties.Specifically,with the STO buffer layer,the breakdown field is dramatically increased in the Pt/STO/PMN-PT/SRO capacitor due to the existence of an internal field in the STO layer,which prevents the growth of electrical trees from the bottom SRO to the top Pt electrode,and a large W_rec of～48.91 J/cm³,more than 3 times of that of the PMN-PT capacitor,is achieved.However,buffered by the LAO,the Pt/LAO/PMN-PT/SRO capacitor exhibits a reduced relaxor character,which may be ascribed to a pinning effect of nanodomains associated with the charged LAO/PMN-PT interface.As a result,both Wrec andηare significantly lowered,compared to the PMN-PT capacitor.Due to the great benefits in PMN-PT,we applied the method of adding STO buffer layers to Pb（Zr,Ti）O₃（PZT）material.Since the PZT material has large maximum polarization,if the relaxor ferroelectric behavior can be induced,it will be a superior energy storage material.Pt/PZT/SRO/STO films and other PZT films with STO buffer layers at different positions were prepared.Finally,we successfully induced relaxor ferroelectric behavior on this normal ferroelectric material in the Pt/PZT/STO/PZT/SRO/STO film with high W_rec up to 9.16 J/cm³.These results provide physical insights into the modulation of relaxor and dielectric behaviors by engineering the characteristics of buffer layers,demonstrating a way for enhancing energy storage properties in thin-film capacitors.