Study of properties of lanthanum doped SrBi4Ti4O15 ferroelectric ceramics

Ceramic samples SrBi4-xLaxTi4O15 (x =0.00, 0.10, 0.25, 0.50, 0.75, 1.00), have been prepared by solid-state reaction method. T heir structure was analyzed by x-ray diffraction, and their dielectricity and fe rroelectricity were measured. It is found that La-doping does not change the cry stal structure of SrBi4Ti4O15. The remnant pola rization (2P4) in creases at first, then decreases with the increase of La content. The 2P4 reaches a maximum value of 24.2 μC·cm-2, when x is 0.25. The c oerc ive field of SrBi3.75La0.25Ti4O15 is 60.8 kV·cm-1 . The 2P4 increases by about 50% and the Ec decrease s near 25%, compa red with these of SrBi4Ti4O15. Obviously, the f erroelectricity of SrBi 4Ti4O15 is improved by lanthanum doping. The te mperature of p hase transition (Tc) decreased with La cloping. The Tc of SrBi3.75La0.25Ti4O15 is 451 ℃. When x=0.75 and 1.00, the SrBi4-xLaxTi4O15 exhibit the typical characteristics of relaxor ferro electrics.