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The Curie point of lead-barium zirconate titanate PZT ceramic

Witold Z. Mielcarek ,  Dionizy Czekaj ,  Krystyna Prociów ,  Joanna B. Warycha ,  Lucjan Kozielski 

Abstract

A piezoelectric substance is one that produces an electric charge when a mechanical
stress is applied (the substance is squeezed or stretched). Conversely, a mechanical
deformation (the substance shrinks or expands) is produced when an electric field is
applied. An important group of piezoelectric materials are ceramics which are utilized
to make many useful products, such as ceramic resonators, ceramic bandpass filters,
ceramic discriminators, ceramic traps and filters.

In analogy to ferromagnetic materials, the Curie temperature is also used in
piezoelectric materials to describe the temperature above which the material loses
its spontaneous polarization and piezoelectric characteristics. In lead zirconate
titanate, the material is tetragonal below Tc and the unit cell contains a
 displaced central cation and hence a net dipole moment. Above Tc, the material is
cubic and the central cation is no longer displaced from the centre of the unit cell.
Hence, there is no net dipole moment and no spontaneous polarization.

The Curie point was estimated for  PB0.84Ba0.16(Zr0.54Ti0.46)O3+ 1mol% Nb2O5ceramic.

The XRD measurements were carried out with DRON-2 deffractometer using Fe filtered Co
radiation and equipped with the high- temperature attachment.The XRD patterns were
taken in the range from 20o to 80o, as step-scans. The calculation were made with
DHN-PDS computing program.From the changes of lattice constants with temperature it
was determined that at 230oC +/-lOoC the  PB0.84Ba0.16(Zr0.54Ti0.46)O3+ 1mol% Nb2O5ceramic structure fully transformed from tetragonal to cubic one with lattice constant a=4.081 A.

 

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Related papers

Presentation: Poster at 11th European Powder Diffraction Conference, Poster session, by Witold Z. Mielcarek
See On-line Journal of 11th European Powder Diffraction Conference

Submitted: 2008-04-30 11:45
Revised:   2009-06-07 00:44