Study of phase transition in Bi3TiNbO9-BaBi2Nb2O9 ceramics

The subject of the paper is lead free bismuth layer structure oxides (1-x)Bi₃TiNbO₉-xBaBi₂N₂O₉(x=0; 1; 2; 3 mol). The influence of Bi₃TiNbO₉/BaBi₂Nb₂O₉ ratio on dielectric and structural properties was studied in a wide range of temperatures. Change in the ratio causes a decrease in the maximum value of dielectric permittivity and shifts the temperature of ε`_max to low values, leading to linear decreasing of average grain size and linear increasing of ceramics density. These results indicate an augment of the packing degree and the participation of pores are significantly decreased with the increase of BaBi₂Nb₂O₉compound intake. Moreover, for 0.7Bi₃TiNbO₉-0.3BaBi₂Nb₂O₉ ceramics the dielectric phase transition is broadened and the properties characteristic for the ferroelectric relaxor appear.