2020 年 57 巻 2 号 p. 88-96
Multilayer technology has become indispensable for the miniaturization of electronic devices and reduces the working voltage of their piezoelectric components. This tutorial paper describes the processing of reduction-resistant BaTiO3-based piezoceramics with excellent properties for multilayer-type component using base metal internal electrodes. Nonreducible (Ba,Ca)(Ti,Sn)O3 ceramics that exhibited a high piezoelectric constant equivalent or superior to that of samples prepared in air were successfully fabricated at temperatures below the melting point of Ni metal. A desired reducing atmosphere was achieved by controlling the oxygen partial pressure with a suitable mixture of Ar, H2, and CO2 gases. Li2CO3 addition promoted grain growth in the ceramic samples, which were highly polarized following poling treatment. Optimizing the amount of Li2CO3 added to (Ba,Ca)(Ti,Sn)O3 ceramics sintered under a low oxygen partial pressure resulted in improved piezoelectric properties while maintaining the high sintered density. Reduction-resistant BaTiO3-based ceramics developed in this study are promising lead-free materials for applications in multilayer piezoelectric components.
