L. AMARANDE, C. MICLEA, C. TĂNĂSOIU, C. F. MICLEA, A. IUGA, M. CIOANGHER
Piezoelectric Properties of Lead Titanate Ceramics Modified with Donor Dopants

Abstract.
Effect of small amounts (2–10 mol%) of Bi and Y donor additives on the piezoelectric properties of PT ceramics was investigated. The samples were prepared by conventional ceramic technique, using p.a. purity raw materials. The mixed powders were sintered at temperatures between 1 000–1 300°C. Poling was done in fields of about 70 kV/cm. Density and electromechanical coupling factors of the samples were determined as a function of sintering temperatures, and doping level. Temperature dependence of the main piezoelectric characteristics was also investigated for temperatures as high as 500ºC. A high Curie point (> 450ºC), a low dielectric constant (< 140) and a large electromechanical anisotropy (the radial mode is nearly inexistent, at room temperature and the thickness coupling factor is about 0.4) were found. These enhanced properties make such ceramics very attractive for high temperature and high frequency transducers applications.