STUDYING THE MECHANICAL PROPERTIES OF BARIUM STRONTIUM TITANATE CERAMICS BY AN ULTRASONIC PLUSE ECHO TECHNIQUE

Ba1-xSrxTiO3 (0 <= x <= 0.5) ceramics were prepared by solid state reaction. X- ray diffraction pattern and FMSEM micrographs showed the compositions of these ceramics are single tetragonal phase except for Ba0.5Sr0.5TiO3 showed single cubic phase. The crystal size and the lattice parameters decreased as Sr content increases and confirm the formation of single phase. Mechanical properties were studied by an ultrasonic pulse echo technique at 2 MHz. Increasing of Sr content led to remarkable increase in all elastic moduli. The values of longitudinal modulus (L), shear modulus (G), Young's modulus (E), and bulk modulus (B) increased from 9.15 to 20.64 GPa, 3.29 to 7.43 GPa, 8.02 to 18.11 GPa, and 4.76 to 10.73 GPa, respectively. High temperature ultrasonic studies showed that the Curie transition temperature depends on the content of Sr in the compositions, where to shift from 353.7 to 290 degrees C with increasing Sr content. Also, the appeared two relaxation peaks and its origin were investigated.