The contribution from the irreversible displacement of non- domain walls to the direct longitudinal piezoelectric coefficient of and ceramics was determined quantitatively by using the Rayleigh law. Effects of the crystal structure and microstructure of the ceramics as well as the external d.c. pressure on the domain wall contribution to were examined. In barium titanate, this domain wall contribution is large (up to 35% of the total , under the experimental conditions used) and dependent on the external d.c. pressure in coarse grained ceramics, and much smaller and independent of the external d.c. pressure in fine-grained samples. The presence of internal stresses in fine-grained ceramics could account for the observed behaviour. The analysis shows that the domain-wall contribution to the in lead zirconate titanate ceramics is large in compositions close to the morphotropic phase boundary that contain a mixture of tetragonal and rhombohedral phases, and in rhombohedral compositions (up to 40% of the total ). The domain-wall contribution to the piezoelectric response from the irreversible displacement of domain walls is significantly smaller in tetragonal samples where it decreases with increasing spontaneous strain.
The direct longitudinal piezoelectric effect in lead zirconate titanate, barium titanate, bismuth titanate and strontium bismuth titanate ceramics was investigated with respect to the dependence on the amplitude of an alternating pressure. At low alternating pressure amplitudes, the behaviour of the piezoelectric charge and the piezoelectric coefficient may be explained in terms of the Rayleigh law originally discovered for magnetization and magnetic permeability in ferromagnetic materials. The charge versus pressure hysteresis loops measured for piezeoelectric ceramics may similarly be described as the Rayleigh loops. The results presented show that the Rayleigh law can be applied to irreversible displacement of several types of non- ferroelectric domain walls and imply universal validity of the Rayleigh law for displacement of ferromagnetic, ferroelastic and ferroelectric domain walls.
Microstructure dependence of electrical properties of (Ba0.5Sr0.5)TiO3 thin films deposited on Pt/SiO2/Si Investigation of the stressdependent magnetic easy axis in steel using magnetic Barkhausen noise
A phase diagram based on dielectric-permittivity-versustemperature measurements and high-temperature X-ray diffractometry was proposed for 0.4Pb(Ni 1/3 ,Nb 1/3 )O 3 -xPbZrO 3 -(0.6−x)PbTiO 3 (0.2 ≤ x ≤ 0.32) relaxor-ferroelectric solid solution, and a morphotropic phase boundary that sharply bends toward zirconium-rich compositions was found. A spontaneous normal-to-relaxor ferroelectric transition was also observed when heating was performed for all the compositions tested near the morphotropic phase boundary. Additional considerations about previously published phase diagrams for Pb(Zn 1/3 ,Nb 2/3 )O 3 -PbTiO 3 and Pb(Mg 1/3 ,Nb 1/3 )O 3 -PbTiO 3 might lead to an extension of the presented diagram to these compositions.
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