DIELECTRIC AND PIEZOELECTRIC PROPERTIES OF PB(YB1/2NB1/2)O-3-PBTIO3 - SOLID-SOLUTION SYSTEM

Solid solutions of (1-x)Pb(Yb1/2Nb1/2)O-3-(x)PbTiO3 x=0 to 0.8 were investigated from the viewpoint of dielectric and piezoelectric properties. With increasing PbTiO3 content (x), phases at room temperature continuously changed from antiferroelectric (x=0), ferroelectric (x=0.1 to 0.15), relaxer (x=0.2 to 0.49), and again to ferroelectric (x>0.49), where crystal structures of all these phases were perovskite. Sintering temperature was lowered to around 950 degrees C in the relaxer phase (x=0.2 to 0.49). Piezoelectric constants exhibited a maximum at x=0.49 to 0.50 near the morphotropic phase boundary (x=0.49). In the sample with x=0.50, Curie point was 349 degrees C, and remanent polarization and coercive field were 32.8 mu C/cm(2) and 2.75 kV/mm, respectively. Also, electromechanical coupling factors for planar (k(p)) and thickness (k(t)) modes were 0.527 and 0.436, respectively.