Temperature stability, phase structure and electrical behavior of Li-modified 0.99(K0.48Na0.52)NbO3–0.01BiCoO3 piezoelectric ceramics

Abstract High temperature applications of piezoelectric ceramics require not only high Curie temperature ( T C ), but also good thermal stability in a wild temperature range. To achieve this goal, 0.99[(K 0.48 Na 0.52 ) 1− y Li y ]NbO 3 –0.01BiCoO 3 [KNLN- y -BC] piezoelectric ceramics have been prepared by a conventional solid-state sintering method. The effects of lithium on the phase structures, electrical properties, and thermal stability were investigated. A polymorphic phase boundary between orthorhombic and tetragonal phases has been found in the composition range of 0.02≤ y ≤0.03 at room temperature. With the increasing content of Li, T C gradually raised while T O–T reduced, respectively. The T O–T value of KNLN-0.03-BC ceramic is close to room temperature, resulting in good electrical properties ( d 33 ∼180, k p ∼0.326). Moreover, KNLN- y -BC ceramics possess a lower T O–T and higher T C (>400 °C) when y ≥0.03, that means they have a better thermal stability and might be used in a broader temperature range.