Effect Of K_0.5Na_0.5NbO₃Filling Particles On The Charge Carrier Trap Distribution Of Polyimide Films

With the fast development of the electric power and electrical industry, singleinorganic and organic dielectric substance does not meet the demand ofminiaturization and high performance. This article research the effect ofK0.5Na0.5NbO3(KNN50) filling particles on the charge carrier trap distribution ofpolyimide films and hope to find a high-performance dielectric material.First, polyimide (PI) films filled with K0.5Na0.5NbO3particles at different weight0wt%,5wt%,10wt%and15wt%had been prepared by in-situ dispersionpolymerization process in this article. The thermally stimulated current (TSDC)method was used to investigate the charge carrier trap levels and their distribution ofthe composite films. The TSDC spectra shows that pure film has α-peak andβ-peak, but the composite films only have α-peak and an extraordinary peak athigh temperature region. The trap parameters were calculated by an approximatemodel, and the result indicate that charge released of the shallow traps show anonlinear behavior. The trap energies decrease from0.879-0.968eV to0.549-0.839eVwith the increase of the KNN50content. The surface and interface between KNN50and PI matrix was considered to the variation of the trap levels. The extraordinarypeak of the composite films was correlated with the phase transition of the KNN50particles.Then the resistance of the corona destruction and dielectric spectra of thecomposite films were tested. Corona experimental results show that the change ofability of the corona resistance levels of the films with increasing doping is nonlinear.The corona resistant performance increased when the doping content less than5wt%. And with the increasing of the KNN50the corona resistant performance decreasedgradually until the doping content of10wt%and then increased significantly. Theresults are connected with the increase of surface and interface and the extent ofKNN50particles damage to the main chain. The dielectric spectra test results showthat when the doping content is less than5wt%the dielectric of the composite filmsdecreased, while increases gradually when the doping content higher than10wt%. Itrelates to the factors which affecting the levels of space charge distribution. Thedielectric loss factor is increase with the increase of doping content of the mainreason may be the doping of KNN50particle would introduce deep traps in thematerial. And these deep traps would polarization form dipole when under an electricfield, which increase the dielectric loss factor.