Dielectric and Piezoelectric Properties of Mn-Modified Bi4CaTi4O15Based Ceramics

Solid solution ceramics of the Bi 4 Sr x Mn y Ca 1-( x + y ) Ti 4 O 15 system were synthesized by the conventional ceramic process. Measurements of dielectric, electromechanical and piezoelectric properties were conducted as a function of both composition and temperature. As a result, it was found that piezoelectric properties are greatly improved as the appropriate amount of Mn ion is introduced into the Ca ion-site. Maximum values obtained are as follows: electromechanical coupling factor k P =0.064, piezoelectric constant d 33 =21 pC/N for the composition with x =0.5 and y =0.1 (Bi 4 Sr 0.5 Mn 0.1 Ca 0.4 Ti 4 O 15 ), and the mechanical quality factor Q m =3250 for the composition with x =0.5 and y =0.05 (Bi 4 Sr 0.5 Mn 0.05 Ca 0.45 Ti 4 O 15 ). Piezoelectric constant d 33 was found to take nearly the same value of 20 pC/N over the range of x =0.4 to 0.9 for the fixed y of 0.1.