| Transparent ferroelectric ceramics are a kind of multi-function materials,which can combine with optical,electrical and mechanical properties of the ceramics,causing a serious of special phenomenons,and can be applied in many fileds.Thus,in this work,to achieve high transparent ceramics,the control of relaxor structure and grain size of the ceramics as main thought,a second component A(Mg1/3Nb2/3)O3(A=Sr,Ba Bi)were added into KNN,and the A(Mg1/3Nb2/3)O3(A=Sr,Ba,Bi)content and A-site ion were changed to control the relaxor structure and grain size of the ceramics to obtaine tansparent ceramics by using traditional solid state reacting method.Meanwhile,the relationship among phase structure,microstructure,optical properties and electric properties were investigated systematically.The main conclusions as follow:(1)The effect of different MgO purity on the density and their properties of the 0.96KNN-0.04SMN ceramics were studied.The results showed that the raw materials with higher purity is beneficial to obtain higher densification structure,thus the optical and electrical properties of the ceramics were improved.With the MgO purity improved from 98.5%to 99.99%,the phase structure was not changed,the relative density of the ceramics was improved from 96.1%to 97.4%.The transmittance of the ceramics was improved from 40%to 50%in the near infrared region,and the maximum dielectric constant,remnant polarization and piezoelectric constant were improved.(2)The(1-x)KNN-xSMN transparent ceramics were fabricated through changing SMN content,and the effect of SMN content on phase structure,microstructure,optical,electrical properties and their relationship were investigated systemically.With increasing SMN content,the phase structure of the ceramics was transformed from orthogonal to pseudo cubic phase,the grain size of the ceramics was decreased gradually,the ceramics with x = 0.05 possessed of fine and uniform grains and the highest relative density value of 98.6%.The transmittance of the ceramics was firstly increased and then decreased slightly,and the ceramics with x = 0.05 possessed of the highest transmittance of 60%in the near infrared region.The maximum dielectric constant,remnant polarization and piezoelectric constant of the ceramics were decreased and the Curie temperature was shifted to room temperature with increasing of SMN content.The ?T value and diffusion factor y of the samples were increased with the increasing of x content,suggesting that the ralaxor behavior enhanced,giving rise to polar nano-regions and making the light scattering decreased,thus,the transmittance of the ceramics was improved.(3)The(1-x)KNN-xBaMN transparent ceramics were fabricated through changing BaMN content,and the effect of BaMN content on phase structure,microstructure,optical,electrical properties and their relationship were investigated systemically.With increasing BaMN content,the phase structure of the ceramics was transformed from orthogonal to pseudo cubic phase,and the grain size were suppressed effectively,the ceramics with 0.04? x? 0.06 possessed of fine and uniform grains,and denser structure with higher relative density value of over 99%were obtained.The transmittance of the ceramics was firstly increased and then decreased,and the ceramics with 0.04? x?0.06 possessed relatively higher transmittance of over 70%in the visible region and over 80%in the near infrared region.The AT value and diffusion factor y of the ceramics were firstly increased and then decreased with x increasing,and the diffusion factors y were 1.95,1.97 and 1.99 respectively when 0.04? x?0.06,suggesting that the ceramics with 0.04? x?0.06 were close to typical relaxor ferroelectrics.Meanwhile,the maximum dielectric constant and remnant polarization of the samples were decreased,and the Curie temperature was shifted to room temperature with increasing of BaMN content.(4)The(1-x)KNN-xBiMN transparent ceramics were fabricated through changing BiMN content,and the effect of BiMN content on phase structure,microstructure,optical,electrical properties and their relationship were investigated systemically.With increasing BiMN content,the phase structure of the ceramics was transformed from orthogonal to pseudo cubic phase,the grain size were suppressed effectively.All the ceramics possessed of fine grains below 200 nm,and denser structure were obtained.The transmittance of the ceramics was firstly increased and then decreased,the ceramics with 0.06? x? 0.09 possessed of relative higher transmittance over 75%in the visible region and close to 85%in the near infrared region.The ?T value and diffusion factor y of the samples were initially increased and then decreased with increasing BiMN content,the diffusion factor y was close to 2 with the ceramics of 0.06 ? x? 0.09,suggesting the ceramics with 0.06? x? 0.09 were close to typical relaxor ferroelectrics.Meanwhile,the maximum dielectric constant and remnant polarization of the samples were initially increased and then decreased,and the Curie temperature was shifted to room temperature with increasing of BiMN content.The ceramics of x =0.07 obtained highest maximum dielectric constant and remnant polarization,the value of which is 1864 and 1.9 ?C/cm2,respectively.(5)The 0.93KNN-0.07BixMN(x = 0.60,2/3,0.75,0.85,0.95,1.0,1.05)transparent ceramics were fabricated through changing Bi content,and the effect of Bi non-stochiometry on phase structure,microstructure,optical,electrical properties and their relationship were investigated systemically.With increasing Bi content,the phase structure of the ceramics was not changed,and all showed pseudo cubic structure.All the ceramics possessed of fine and uniform grains,and part of Bi played as a sintering aid improving the density of the ceramics when Bi content was higher.The transmittance of the ceramics was increased firstly and then became saturated with increasing Bi content,the ceramics with x>0.85 possessed of relatively higher transmittance of over 75%in the visible region.The impedance results showed that part of Bi offset the volatilization of K,Na and Bi element with increasing Bi content,causing the decrease of defect of the ceramics and thus improving the transmittance of the ceramics.In addition,the dielectric constant and remnant polarization were slightly improved with increasing Bi content. |
PDF Full Text Request