Study On The Preparation Of Composite And Thin Film Of Barium Titanate Micro-Nano Powder For Capacitor Energy Storage

BaTiO₃?Hereinafter referred to as BT?is widely used in electrical memories,semiconductors,sonar,detectors and piezoelectric devices due to its ferroelectric and piezoelectric properties.In recent years,barium titanate materials have received extensive attention due to their high dielectric constant,low loss,and high breakdown strength.Barium titanate ceramic polymer-based composite films have excellent dielectric properties,good flexibility,and stability,so it is expected to produce high performance dielectric capacitors.For ceramic polymer-based composite dielectric films,the properties of ceramic fillers,including their inherent dielectric properties,surface properties,size distribution,size and morphology,are key factors influencing the dielectric properties of composite films.Obviously,the intrinsic dielectric properties of ceramic fillers directly affect the dielectric properties of composite films.In addition,the size,morphology,and surface characteristics of the filler can affect the compatibility and dispersibility of the filler in the polymer matrix.Therefore,dimensional control and surface modification of ceramic fillers are critical to improving the dielectric properties of ceramic composite films.This study firstly uses a simple sanding method to treat commercial barium titanate powder,and controls the dielectric properties of barium titanate/resin composite film by controlling the particle size of barium titanate filler.Secondly,the composition,morphology and particle size distribution of barium titanate nanocrystals were precisely controlled by hydrothermal method,and the growth mechanism of barium titanate nanocrystals was studied.The details of research and conclusions are mainly divided into the two parts as follows.?1?Preparation and dielectric properties of BaTiO₃/resin/aluminum?Hereinafter referred to as BPA?composite films.BaTiO₃ particles are mixed with a silane coupling agent?KH550?and processed at different durations of wet sand grinding.The particle size of barium titanate fillers is adjusted by sanding time,meanwhile the barium titanate filler and the silane coupling agent are fullymixed.Then,the BT/KH550 filler is mixed with a silicon-containing heat-resistant resin?CYN-01?to obtain a coating slurry.Finally the BaTiO₃/resin/aluminum composite dielectric film was fabricated by coating the obtained coating slurry on an aluminum foil through a roll coating and thermal curing process.The effects of BaTiO₃ to resin ratio and BaTiO₃ particle size on the morphology and dielectric properties of BPA films were investigated.The results show that the BaTiO₃ particles treated by sand grinding and KH550 silane coupling agent can improve the dielectric properties of BPA film,and at the optimal condition,a dielectric constant of 32,a breakdown strength of 20.8 V/?m and a dielectric loss of 0.014 were obtained.This work provides a simple but industrial strategy to fabricate ceramic/polymer composite films for energy-storage capacitor applications.?2?Hydrothermal synthesis of spherical BaTiO₃ nanoparticles using TiO₂?P25?nanocrystals as titanium source.The hydrothermal synthesis of spherical BaTiO₃ nanoparticles is of great significance for the miniaturization of BaTiO₃-based electronic devices.In this study,TiO₂?P25?crystal was used as seed crystal and titanium source,and Ba?NO₃?₂ was used as Ba source.In the strong alkaline?NaOH,2 mol/L,pH=13.6?solution,spherical BaTiO₃nanocrystals?90–100 nm?were hydrothermally synthesized.The phase,size and morphology of BaTiO3 nanocrystals were controlled by adjusting the reaction parameters such as Ba/Ti molar ratio(R_Ba/Ti=1.6–2.5),hydrothermal temperature?T=150–210??and reaction time?t=2–16 h?.The obtained BaTiO₃ samples were characterized by X-ray diffraction?XRD?,scanning electron microscopy?SEM?and FT-IR spectroscopy.The results show that the high Ba/Ti ratio,the high hydrothermal temperature??200 ^oC?and the long hydrothermal time??8 h?in favor of the formation of cubic/tetragonal BaTiO₃ spherical nanocrystals with uniform particle size distribution?90–100 nm?.Under the optimal conditions([NaOH]=2.0 mol/L,R_Ba/Ti=2.0,T=210°C,t=8 h),the BaTiO₃ nanospherical have a narrow particle size range of 91±14 nm.The hydrothermal method with TiO₂ is a simple process to control grain size of BaTiO₃nanospherical.