Abstract: CaCu3 Ti4 O12 ( CCTO ) ceramics doped by La 3+ were prepared by the solid state reaction method.The phase structures , microstructures, and dielectric properties of the Ca 1-x Lax Cu3 Ti4 O12 ( x=0;, 1;, 3;, 5;, 7;) ceramics were investigated .The mechanism of influence of La 3+doping on the dielectric properties of CCTO ceramics was analyzed .The results show when x is 3;, secondary phases appear , when x is higher than 5;, the ceramic grains become smaller , La3+doping remarkably increases the dielectric constant of CaCu 3 Ti4 O12 ceramics, and the dielectric loss also becomes lower than undoped CaCu 3 Ti4 O12 ceramics over the high frequency range , which improved the general dielectric properties of CCTO ceramics .

Key words: CaCu3 Ti4 O12 ( CCTO ) ceramics doped by La 3+ were prepared by the solid state reaction method.The phase structures , microstructures, and dielectric properties of the Ca 1-x Lax Cu3 Ti4 O12 ( x=0;, 1;, 3;, 5;, 7;) ceramics were investigated .The mechanism of influence of La 3+doping on the dielectric properties of CCTO ceramics was analyzed .The results show when x is 3;, secondary phases appear , when x is higher than 5;, the ceramic grains become smaller , La3+doping remarkably increases the dielectric constant of CaCu 3 Ti4 O12 ceramics, and the dielectric loss also becomes lower than undoped CaCu 3 Ti4 O12 ceramics over the high frequency range , which improved the general dielectric properties of CCTO ceramics .