PROCESSING AND PROPERTIES OF Na0.5Bi0.5TiO3 PIEZOELECTRIC CERAMICS MODIFIED WITH La, Mn AND Fe

Although a great deal of work has been done to understand defect chemistry in "soft" and "hard" PZT-based materials, there is little understanding of how defect chemistry influences the properties of lead-free piezoelectric materials. This paper reports a systematic investigation of doping on the ferroelectric and piezoelectric properties in Na0.5Bi0.5TiO3 (NBT)-based ceramics. NBT-based ceramics have been synthesized by traditional solid state routes using several different dopants including lanthanum, manganese, and iron in 1mol%. The addition of iron and manganese lead to an increase in the coercive field (E-c), a decrease in the piezoelectric coefficient (d(33)), and an increase in the thermal depoling temperature (T-depole), similar to the behavior of "hard" PZT. Lanthanum, on the other hand, leads to a decrease in the E-c, an increase in d(33), and a decrease in T-depole similar to that seen in "soft" PZT.