Details

Autor(en) / Beteiligte

• CASTRO, A
• MILLAN, P
• PARDO, L
• JIMENEZ, B
• WCA

Titel

Synthesis and sintering improvement of Aurivillius type structure ferroelectric ceramics by mechanochemical activation

Ist Teil von

• Journal of materials chemistry, 1999, Vol.9 (6), p.1313-1317

Ort / Verlag

Cambridge: Royal Society of Chemistry

Erscheinungsjahr

1999

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• An oxide mixture of composition 3Bi2O3:Nb2O5:2TiO2 was mechanochemically activated in a laboratory mill for different times from 3 to 336 h. The as-milled powder and an unmilled mixture of identical composition were annealed at different temperatures up to the formation of the Aurivillius-type oxide Bi3NbTiO9, and examined by XRD and DTA. The sample milled for 336 h shows complete amorphisation. Its DTA curve exhibits two exothermic processes at 370 and 560 C, corresponding to the formation of a metastable fluorite phase and the Aurivillius-type oxide, respectively. The crystallisation temperature of this Aurivillius phase from the unmilled oxide mixture is reported to be 1050 C, whereas, from the amorphous powder obtained by 336 h of mechanochemical activation, this temperature becomes as low as 600 C. Ceramics of this composition must be prepared by hot-pressing in order to obtain low porosities, owing to the lamellar morphology of the conventionally crystallised powder, which gives rise to textured anisotropic materials. Non-textured ceramics were obtained both from the conventionally crystallised and the amorphous powder by sintering at 1100 C. Ceramics obtained from amorphous powder show lower porosity and higher electromechanical coupling factors. 32 refs.