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Nanostructuring of Electroceramics: Phase Stabilization Induced by Nanoparticles
|PAULA M. VILARINHO|
Universidade de Aveiro (UA), Departamento de Física, Aveiro 3810-193, Portugal
Pb(B'1-xB"x)O3 is currently an important family of functional materials. Their value added comes from the excellent dielectric, piezo-, pyro- and ferroelectric properties that they exhibit, being very attractive for multilayer capacitors, piezoelectric transducers, infrared sensors, electrooptic devices, memory applications, to operate under different frequency / temperature conditions. A successful application highly depends on the easiness to adapt the material to the required fabrication technology and to integrate it in a useful and reliable device. Low synthesis temperature that ensure phase purity and minimise interdiffusion is a key aspect for manufacturing Pb(B'1-xB"x)O3 bulk ceramics and films. However it is well known that during synthesis a stable pyrochlore phase (A2B2O7-d) with low dielectric permittivity precedes the formation of the perovskite (Pe) and if it remains degrades the material dielectric response. The crystallization temperature to obtain monophasic Pe materials can then limit their practical application. In this work a new methodology to synthesize Pb(B'1-xB"x)O3 compounds is presented. It combines maximization of crystalo-chemical and thermodynamics requirements for Pe phase stabilization and optimization of the phase formation reaction kinetics by supplying highly reactive nanometric Pe nucleus. It is expected that nanometric Pe particles will act as template for synthesis of Pe at low temperatures, even in those systems in which monophasic materials were reported to be extremely difficult to be obtained. The effect of nanopowders on Pe phase formation is analyzed in two systems: Pb(Zn1/3Ta2/3)O3(PZTa) ceramics and PZT films. For comparison similar materials are prepared by conventional methodologies. XRD, SEM and TEM are used to evidence the role of nanoparticles on Pe phase nucleation and growth. Through a systematic study of the electric response correlation between materials morphology and macroscopic properties is established.
Presentation: invited oral at E-MRS Fall Meeting 2004, Symposium G, by PAULA M. VILARINHO
See On-line Journal of E-MRS Fall Meeting 2004
Submitted: 2004-05-01 21:31 Revised: 2009-06-08 12:55