Preparation And Study Of Dielectricity Of Rare-Earth Element Modified BaTiO₃

As an excellent electronic ceramic,BaTiO₃ has been widely used in various fields because of its excellent properties in ferroelectric,piezoelectric and dielectric.As the electronics industry develops rapidly,properties of BaTiO₃ are in high demand.There are research shows that the properties of BaTiO₃ are closely associatied with its crystal structure.Regarding this,it is obviously very important and valuable to improve the property of BaTiO₃ by doping it with other elements.In this paper,we researched the influence of rare earth elements doping BaTiO₃ on its electrical property.To study the influence of rare earth elements?RE=La,Sm,Er,Yb?doping BaTiO₃on its crystal structure,phase content and electrical property,we prepared rare-earth doping BaTiO₃ by solid phase synthesis.The phase structure of samples were analysed by XRD and Rman spectrum,and then summarize the relationship between crystal contants and dopants.We measured the dielectric property of samples by waveguide method on vertical network analyzer,and measured the high temperature resistivity resistance tester.Thus we can determin the relationship between the properties and dopants.The main conclusions of this paper are shown as below:1.Preperation and analyse of La-doped BaTiO₃.When the doping amount was in a low level??8mol%?,La³⁺mainly replaced Ba²⁺;and with the increase of doping content,the crystal constants were smaller,the tetragonality decreased and the crystal phase transfered from tetragonal to false cubic.When the amount reached 10mol%,La³⁺still replaced Ba²⁺mainly,but it also started to replace Ti⁴⁺.With the test frequency increased,both the real part and the imaginary part of the dielectric constants of samples decreased;the real part reached a maximum between 12GHz-13GHz;when doping amount was 10mol%,and when it was 2mol%,the imaginary part reached a minimum between 12GHz-13GHz,and so does the dielectric loss.2.Preperation and analyse of Sm-doped BaTiO₃.Like La-doped BaTiO₃,when the doping amount was in a low level??8mol%?,Sm³⁺mainly replaced Ba²⁺,and with the increase of doping content,the crystal constants were smaller,the tetragonality decreased and the crystal phase transfered from tetragonal to false cubic.;but unlike La-doped BaTiO₃,when the amount reached 10mol%,Sm³⁺mainly replaced Ti⁴⁺instead,the crystal phase increased.With the test frequency increased,both the real part and the imaginary part of the dielectric constants of samples decreased;when doping amount was 10mol%,both the real part and imaginary part reached a maximum,so do the dielectric loss.3.Influence of different doping elements at 2mol%dopants.When the ionic radii was large,the doping ionic mainly replaced Ba²⁺;but when the doped with Yb,Yb³⁺mainly replaced Ti⁴⁺.With the corresponding,as the ionic radii decrease,the crystal constants increased at first and then decreased,and when doped with Er,the crystal contants reached a maximum,so do the real part of dielectric constants;when doped with La,the dielectric loss reached the top.