Stress-induced phase transition in lead-free relaxor ferroelectric composites

(Na1/2Bi1/2)TiO3‐based lead‐free co‐fired multilayer actuators with large strain and high fatigue resistance

“…A similar effect of internal residual stress on the temperature‐dependent permittivity of NBT–BT‐based piezoceramics was reported for NBT–6BT:ZnO composites. Due to the difference in CTE between ZnO and NBT‐6BT, residual thermal stress is generated upon cooling from the sintering temperature and was suggested to stabilize the ferroelectric order to a higher temperature . Note that the dielectric constant of the multilayer actuator is significantly smaller than that of bulk ceramics, which is mainly due to the higher porosity and the difficulty to accurately determine the active area.…”

“…Due to the difference in CTE between ZnO and NBT-6BT, residual thermal stress is generated upon cooling from the sintering temperature and was suggested to stabilize the ferroelectric order to a higher temperature. 30 Note that the dielectric constant of the multilayer actuator is significantly smaller than that of bulk ceramics, which is mainly due to the higher porosity and the difficulty to accurately determine the active area. Different from the dielectric constant, the loss factor of the multilayer actuator is only slightly affected at low temperatures.…”

Orientation dependence of electric field induced phase transitions in lead‐free (Na0.5Bi0.5)TiO3‐based single crystals

“…Among the promising candidates to partially replace PZT ceramics, (Na 0.5 Bi 0.5 )TiO 3 (NBT)‐based solid solutions, for example with BaTiO 3 (BT), are intensively studied due to their high electromechanic properties . The (1– x %)(Na 0.5 Bi 0.5 )TiO 3 – x %BaTiO 3 (NBT– x BT) system has a morphotropic phase boundary (MPB) at a BT content of x = 6‐7, where NBT– x BT materials possess intriguing structural and piezoelectric properties .…”

Lead-free piezoceramics: Status and perspectives

“…92 At the same time, new materials (e.g., based on bismuth ferrite) 29 and new physical mechanisms are being discovered. In terms of new mechanisms, the opportunities to enhance depolarization temperature by either quenching 93 or using composites 94,95 and by hardening through hard second phases 96 seem particularly noteworthy.…”