Ageing of low field dielectric constant and losses in (Hf, Zr)-doped ceramics

Al. I. Cuza University, Faculty of Physics - Blvd. Copou, 11, Iasi 6600, Romania

Corresponding author: vtura@uaic.ro

Received: 22 June 1999
Accepted: 18 April 2000

Abstract

Ageing properties of weak field dielectric constant and losses of (Hf, Zr)-doped ceramics in various crystalline phases are studied, and compared with those of pure tetragonal ceramics. At room temperature, the ageing process develops following two different mechanisms: a thermally activated ageing process in pure tetragonal ceramics and a defects diffusion for the doped ceramics. We consider that the main reason for the different ageing mechanisms is the crystalline symmetry, which influences the twinning process and the domain-wall dynamics. Our results prove that ageing of (Hf, Zr)-doped ceramics depends on temperature by intermediate of the phase symmetry, which imposes the twinning rate and rearrangement of ferroelectric domains minimizing the elastic energy of the lattice.