Submicron-structured (Bi0.5Na0.5)0.94Ba0.06TiO3 (BNBT6) ceramics were obtained from nanometric powder synthesized by sol-gel auto-combustion at 500°C. Hot-pressing at low temperatures and a combination of this with recrystallization, still moderate in order to reduce the loss of volatile elements, have been tested. Material properties, including all losses, were determined at the resonances of thin discs using Alemany et al software. Ceramics hot-pressed at 700-800°C for 2h have a pseudo-cubic structure, a grain size of a few hundred nanometers and are homogeneous. Both their crystal structure and the lack of sintering prevent their poling. For ceramics hot-pressed at 950°C for 3h, Bi or Bi0.5Na0.5 loss, together with low piezoelectric properties (d33=60 pC N−1, kp=8.3% and kt=9.5%), was observed. Recrystallization at 1000°C-1 h of ceramics hot-pressed at 700 and 800°C for 2h keeps the submicron structure,reduces porosity and prevents off-stoichiometry. Mechanical and piezoelectric losses are also reduced and coupling factors increased (kp=24.6%, kt=36.4%). The best piezoelectric coefficient obtained in these ceramics (d33=143 pC N−1) is comparable with those reported for coarse-grained ceramics
Piezoelectric properties of lead-free submicron-structured (Bi0.5Na0.5)0.94Ba0.06TiO3 ceramics from nanopowders
Mercadelli E;Galassi C
2010
Abstract
Submicron-structured (Bi0.5Na0.5)0.94Ba0.06TiO3 (BNBT6) ceramics were obtained from nanometric powder synthesized by sol-gel auto-combustion at 500°C. Hot-pressing at low temperatures and a combination of this with recrystallization, still moderate in order to reduce the loss of volatile elements, have been tested. Material properties, including all losses, were determined at the resonances of thin discs using Alemany et al software. Ceramics hot-pressed at 700-800°C for 2h have a pseudo-cubic structure, a grain size of a few hundred nanometers and are homogeneous. Both their crystal structure and the lack of sintering prevent their poling. For ceramics hot-pressed at 950°C for 3h, Bi or Bi0.5Na0.5 loss, together with low piezoelectric properties (d33=60 pC N−1, kp=8.3% and kt=9.5%), was observed. Recrystallization at 1000°C-1 h of ceramics hot-pressed at 700 and 800°C for 2h keeps the submicron structure,reduces porosity and prevents off-stoichiometry. Mechanical and piezoelectric losses are also reduced and coupling factors increased (kp=24.6%, kt=36.4%). The best piezoelectric coefficient obtained in these ceramics (d33=143 pC N−1) is comparable with those reported for coarse-grained ceramicsI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
