Preparation And Properties Of Highly Transparent PMN-PT Based Electro-optic Ceramics

The relaxor ferroelectric(1-x)Pb(Mg1/3Nb2/3)O3-x Pb Ti O3 [PMN-PT(1-x)/x] materials have excellent electrical and optical properties.PMN-PT based ceramic is suitable for development of electro-optic modulator.It have a potential application in the field of optical communication.PMN-PT(1-x)/x powders were prepared by columbite precursor method,and transparent ceramics with high optical transmittance were successfully fabricated in this paper.The effect of powders synthesis processes,sintering methods and different doping contents of La on the microstructures and properties of PMN-PT(1-x)/x ceramics were investigated.The scaling behaviors of PMN-PT75/25 ceramics with different La-doping contents were further studied.Main results and conclusions are as follows:1.PMN-PT(1-x)/x powders were prepared by columbite precursor method.With increasing ball-milling speed,the average secondary particle size has an obvious decrease trend,and the ceramic fabricated by ball-milling speed of 2000 r/min shows the highest optical transmittance.Hot-pressing,oxygen atmosphere and two-stage sintering technology were used to fabricate pure perovskite-phase PMN-PT based ceramics.The one fabricated by two-stage sintering technology has the highest optical transmittance.When the sintering pressure is 6 MPa,PMN-PT ceramic shows the highest optical transmittance 70.2% in the near-infrared wave band.2.PMN-PT75/25 transparent ceramics with different La-doping contents were fabricated using two-stage sintering technology.When La-doping content is 3.0 mol%,ceramic shows high density and low porosity,its optical transmittance is 70% in the nearinfrared wave band,which is very close to its theoretical limit 71%.With increasing La content,(200)peak in XRD patterns shifts to higher angles and the average grain size increases,while the temperature T?max corresponding to the maximum ?r,the remanent polarizations Pr and coercive fields Ec decrease gradually.3.The room-temperature scaling behaviors of PMN-PT75/25 transparent ceramics with different La-doping contents show as follows.For PMN-PT ceramics with low doping contents(La=0,1,and 2.5 mol%),the value of <A> increases quickly at low E0,while gradually becomes stable at high E0.However,PMN-PT ceramics with high doping contents(La=3 and 4 mol%),the stable part is not obvious.In addition,the value of <A> increases with increasing the frequency.The dependence of domain reversal on the f and E0 increased with the increase of La-doping content except for PMN-PT ceramic with La content 2.5 mol%.