| Microelectronic devices was inclined to miniaturization,lightness and high performance with the rapid development of the information technology.Dielectric materials with high dielectric constant,low dielectric loss and good temperature stability are highly desirable.polymer-based materials or inorganic material cannot have both excellent dielectric properties and mechanical properties.Therefore,The preparation of ceramic/polymer composites by mixing high dielectric ceramics and polymers is an effective way to solve this problem.CaCu3Ti4O12(CCTO)ceramics have ultra-high dielectric constant(Up to 10000 1 kHz at room temperature),current-voltage nonlinear effects,good temperature stability,and remarkable dielectric tunability.CCTO should be a good filler.PVDF has good mechanical properties and dielectric properties In the polymer.Therefore,many researchers used CCTO as a filler and PVDF as a matrix to study the dielectric properties of CCTO/PVDF composites.However,the results are not ideal.Therefore,To further improve the dielectric properties of CCTO/PVDF composites,In this study,doping modification of CCTO ceramics by ion doping,preparation of doped ceramic particles/PVDF composites,and it is expected to improve the dielectric properties of CCTO/PVDF composites,at the same time,the preparation conditions of ceramic particles in the preparation process have a great influence on the dielectric properties of composite materials,but there are few studies.Therefore,CaCu3-xMgxTi4O12(CCMTO)and Ca1-3x/2LaxCu3-yMgyTi4O12 ceramic particles were prepared by sol-gel method in different reaction solution Ti concentration,different aging time,different calcination temperature,different calcination time and different doping amount.Then CCMTO/PVDF and CLCMTO/PVDF composites were prepared by ball mill blending and hot pressing.The microstructure,dielectric properties,breakdown strength of composites under different preparation conditions and doping amounts were investigated.Dielectric spectrum detection of composite materials under different preparation conditions.The best preparation conditions are obtained by using high dielectric and low loss as the evaluation standard:The optimal preparation conditions for CCMTO/PVDF and CLCMTO/PVDF composites are the same,the Ti concentration of the reaction solution was 0.7 mol/L,the aging time was 6 h,the calcination temperature was 700?,and the calcination time was 10 h.It can be observed from the XRD pattern of CCMTO ceramic particles that the characteristic peaks of CCTO under different doping contents all indicate the formation of ceramic particles.CCTO has the highest characteristic peak intensity when x=0.1.It can be observed from the SEM image that as the doping content increases,the grains of the ceramic first increase and then decrease,and Maximum grain size when x=0.1.When the filling amount is 50 wt%,the composite material agglomerates.It can be observed from the dielectric spectrum of the composite material that the dielectric constant and dielectric factor of the CCMTO/PVDF composites increase with the increase of the filling amount,and the dielectric constant increases first and then decreases with the increase of the doping content.When x=0.1,the dielectric constant exhibits a maximum value of 96(filling amount of 60 wt%,100 Hz at room temperature),this value is 1.7 times undoped at the same filler content,And the dielectric factor is reduced in the high frequency range compared to the undoped,Therefore,Mg2+doping can improve the dielectric properties of CCTO/PVDF composites.In addition,the breakdown field strength of CCMTO/PVDF composites decreases with the increase of filler,and decreases to 17.66kV.mm-1,when the filling amount is 60 wt%,It was 1.06 times undoped at the same filling amount.It can be observed from the XRD pattern of CLCMTO that the main crystal phases of CCTO exist at different doping contents,indicating the formation of ceramic particles.The characteristic peak intensity of CCTO is highest when x=y=0.05.It can be observed from the SEM image that the grain size of the ceramic particles becomes smaller as the doping content increases.When the filling amount is 60 wt%,the composite material agglomerates.It can be observed from the dielectric spectrum that the dielectric constant and dielectric factor of CLCMTO/PVDF composites increase with the increase of filler,and the dielectric constant and dielectric factor decrease with the increase of doping content.When x=y=0.05,the dielectric constant of the composite often exhibits a maximum value of 90(filling amount of 60 wt%,100 Hz at room temperature),Value is 1.6 times undoped at the same filling amount,so La3+,Mg2+double Doping also improves the dielectric properties of CCTO/PVDF composites.The breakdown field strength of CLCMTO/PVDF composites is improved compared to undoped composites.The value is 1.04 times undoped when the filling amount is 60 wt%. |
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