À δ lead-free piezoelectric ceramics are prepared using solid-state reactions. The use of a Li 2 O sintering aid enables one to obtain dense ceramics at a temperature of 1100 C instead of the 1350 C used for BaTiO 3 (BT) in conventional sintering. X-ray diffraction (XRD) data indicate structural modifications, suggesting insertion of the doping elements into the tetragonal structure. The insertion of Li/Ca/Co/Nb improves piezoelectric properties: for micrograin-size ceramics, a piezoelectric charge constant and an electromechanical coupling factor of d 33 ¼ 255 pC N À1 and k p ¼ 43.5% are reached, respectively. Furthermore, a thermal annealing of the cobalt-doped sample at 1080 C under O 2 atmosphere leads to d 33 ¼ 280 pC N À1 and k p ¼ 44.6%. BaTiO 3 :Co ceramics present distorted ferroelectric cycles due to the occurrence of an internal bias field. The high mechanical quality factors (Q m > 1000) obtained for the doped BT ceramics afford stability against electrical stress of up to 500 V RMS mm À1 , which makes these materials competitive with PZT4 for some applications.
BaTiO 3 ceramic doped with cobalt and calcium (BTCaCo), processed by a conventional technique with a reduced sintering temperature, is characterized. Particular attention is paid to the delivery of complete and accurate set of elastic, dielectric, and piezoelectric constants. These databases are relatively rare in the literature but are essential for numerical simulations of new devices, integrating these materials. The processed piezoelectric material exhibits an electromechanical thickness coupling factor (k t) of 45% and a relative dielectric constant of 1180, at constant strain. A 1-3 piezo-composite is successfully fabricated to improve the performance (k t =47%). Finally, BTCaCo disc is used to fabricate a transducer with a center frequency at 4.3 MHz, showing competitive performance compared to a standard PZT-based transducer.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.