We have studied the structure, relative dielectric permittivity (ɛ), and dielectric loss tangent (tanδ) of SiC-AlN ceramic materials. The results demonstrate that both ɛ and tanδ are anomalously high in the composition range 30–50 wt % AlN at low frequencies (0.1 kHz). We show that the increase in ɛ may be due to a barrier effect on silicon carbide and aluminum nitride grain boundaries and to migration polarization.
Lanthanum doped lead zirconate titanate (PLZT) relaxor ceramics with (Pb0.91La0.09)(Zr0.65Ti0.35)O3 composition exhibit a repolarization induced by electroluminescence (EL) with a pronounced discrete character of emission. It is established that this behavior is related to the reorientation of nanodimensional polar regions in a strong pulsed electric field in the vicinity of a smeared phase transition. The time and temperature dependences of the EL intensity are studied.
Lanthanum-doped lead zirconate titanate (PLZT) relaxor ceramics with (Pb 0.91 La 0.09 )(Zr 0.65 Ti 0.35 )O 3 composition exhibits a repolarization-induced electroluminescence (EL) with a pronounced discrete character of emission. It is established that this behavior is related to the reorientation of nanodimensional polar regions in a strong pulsed electric field in the vicinity of a smeared phase transition. The temporal and temperature dependences of the EL intensity have been studied.
The complex permittivity of ferroelectric PZT ceramics with different compositions was measured in a pulsed rapid-growing electric field. The time dependence of the real component exhibits three peaks. The dips between them correlate with imaginary component peaks. Domain mechanisms that contribute to the ferroelectric polarization and are responsible for the time dependences are considered.
The results of measurements of the dielectric constant of ferroelectric ceramics during polarization in a self-consistent electrical field are discussed.
The role of: non 180 degrees switching in the pulse polarization of ferroelectric ceramic of the PZT system are discussed.