Dielectric, Piezoelectric Properties and Temperature Stability of (Na,K)(Nb,Sb)O3 System Ceramics

In this study, in order to develop lead-free composition for piezoelectric actuator applications, (Na0.525K0.48-x)(Nb0.92-xSb0.08)O-3 + 0.25wt%Bi2O3 + xLiTaO(3) (x = 0.036, 0.037, 0.038, 0.039, 0.040) composition ceramics were fabricated by the normal sintering technique. The piezoelectric properties of resultant ceramics were studied with a special emphasis on the varying of LiTaO3. The structure of the specimen exhibits an orthorhombic perovskite structure. The grain size of the specimen increased with increasing the content of LiTaO3 substitution. High physical properties of the piezoelectric constant d(33) = 317 pC/N, electromechanical coupling factor k(p) = 0.466, dielectric constant epsilon(r) = 1913, and density rho = 4.527g/cm(3) were obtained from the composition ceramics with x = 0.037. Also, at this composition, Delta k(p)/k(p)20 degrees C and Delta f(r)/f(r)20 degrees C showed the maximum value of -0.041 and -0.022 at -20 degrees C and 50 degrees C, respectively. Accordingly, it is considered that the temperature stability of x = 0.037 composition ceramics is suitable for the application of the piezoelectric actuator.