10.0253/TUPRINTS-00002365
UNSPECIFIED
Lead-Free Piezoelectric Ceramics
A number of new lead-free electroceramics have been developed based on the known lead-free ferroelectric system Bi0.5Na0.5TiO3-Bi0.5K0.5TiO3 (BNT-20BKT) at the morphotropic phase boundary by introducing small amounts of K0.5Na0.5NbO3-Bi0.5K0.5TiO3 (KNN-03BKT). With increasing KNN-03BKT content, the materials show a reduction in the ferroelectric and piezoelectric properties. At the same time, the achievable maximum electrostrain peaks at a KNN-03BKT concentration of 1 mol% with 0.46 % at 8 kV/mm. A matrix of 10 compositions surrounding the composition with the highest electrostrain at room temperature was created with 0, 1 and 2 % KNN-03BKT for BNT-19BKT, BNT-20BKT and BNT-21BKT as well as BNT-20BKT-0.5(KNN-03BKT). The large-strain temperature and frequency dependence of these compositions was investigated between room temperature and 200 °C and 50 mHz and 500 Hz. While 8 compositions show typical ferroelectric behaviour, BNT-20BKT-1(KNN-03BKT) and BNT-20BKT-2(KNN-03BKT) both show a high strain at room temperature but very low remanent polarisation and strain. They also both show lower frequency and temperature dependant variation in the large-field strain than the ferroelectric compositions.
Seifert, Klaus Thilo Paul
Klaus Thilo Paul
Seifert
only the rights of use according to UrhG
2010
Thesis