报告内容：

Piezoceramics are currently lead-based, causing toxic by-products, especially during manufacture and waste incineration. Consequently, the search for non-toxic piezoceramics which can replace lead-based materials such as Pb(Zr,Ti)O3 (PZT) is one of the major challenges in science and engineering and BNT-based systems show considerable promise as an alternative. The fatigue behavior of a ferroelectric composition 94BNT-6BT under bipolar and unipolar electrical cycling was investigated as a function of temperature from 25 to >100°C. For both bipolar and unipolar cycling a decrease of polarization, mechanical strain, permittivityε33 and piezoelectric coefficient d33 are observed, with most of the degradation occurring within 104 cycles. In situ neutron diffraction in the unloaded state revealed a phase transformation and formation of ferroelectric order within 1000 cycles at room temperature but then a disappearance of the ferroelectric order with subsequent cycles, despite the retention of piezoelectric properties. However, as temperature increased observable ferroelectric order disappeared at all levels of cycling. The presentation will posit that fatigue behavior in these systems can be explained by an electric field-temperature (E-T) phase relationship with the loci of transitions between phases varying with composition.