Doklady Belorusskogo gosudarstvennogo universiteta informatiki i radioèlektroniki (Nov 2020)
Degradation mechanisms of the Pb1−хBaхZr0,53Ti0,47O3−δ ferroelectric structure
Abstract
The present paper is devoted to the study of the structural degradation mechanisms of ferroelectric having Pb1−хBaхZr0,53Ti0,47O3−δ composition. On the base of investigations of the influence of temperature-time synthesis modes on the structural perfection degree of the Pb0,85Ba0,25Zr0,53Ti0,47O3−8 compound, it has been determined, that a shift of the position of the XRD reflex from the plane (112) and its broadening, which is caused by the amorphization and an increase of the elastic stresses in the material crystal lattice during the annealing of the compound. It has been demonstrated that at the increase of the annealing temperature up to 520 K, the crystal lattice of the ferroelectric is deformed by means of a formation of VPb,V0 and [V О •• 2Pb / i ] defects, which is realized in a decrease of the I(hkl) intensity relationship of the XRD reflexes from the planes (112) and (211). It has been supposed that an excess of lead is produced on the grain boundaries as a result of this annealing process, which promotes a local manifestation of the liquid phase. This phase which takes place in the transfer of the material components, not only increases the interaction of the reacting components, but lowers the stability of their crystal lattices due to the formation of point defects, as well. In this case, the lattice state is determined both by the emergence of the oxygen (VО) and lead (VPb) vacancies, as well as of the associates of the [V О •• 2Pb / i ] type, and by the emergence of various elastic stresses, which promotes the relaxation of the chemical bonds between atoms, caused by the deficiency introduced into the anionic sublattice of the Pb0,85Ba0,25Zr0,53Ti0,47O3−8 solid solution at the oxygen desorption process.
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