Z. Ujma

Relaxor properties of (Pb0·75Ba0·25)(Zr0·70Ti0·30)O3 ceramics

Abstract Dielectric constant and loss factor were investigated as a function of temperature for different frequencies of the measuring field for the (Pb 0·75 Ba 0·25 )(Zr 0·70 Ti 0·30 )O 3 ceramics. Additional measurements of the pyroelectric and thermally stimulated depolarization currents were carried out. The results obtained show distinct correlation. They also prove that these ceramics show properties of relaxor ferroelectrics.

Dielectric and pyroelectric properties of Nb-doped Pb(Zr0.92Ti0.08)O3 ceramics

Abstract Dielectric and pyroelectric characteristics and changes of electric conductivity were investigated for Nb 2 O 5 -doped Pb(Zr 0.92 Ti 0.08 )O 3 ceramics. The influence of this dopant on the ceramics microstructure was also studied. Correlation between the investigated electric characteristics and grain structure was confirmed. Some progress in understanding the influence of Nb-dopant was reached in this way.

Influence of sintering conditions on relaxor properties of BaBi2Nb2O9 ceramics

The main purpose of present studies is to learn the effect of sintering temperature on BaBi2Nb2O9 (BBN) ceramics properties. Grain structure analysis performed by the scanning electron microscope (SEM) exhibits differences in grain structure of the ceramics sintered at various temperatures for a constant time. Namely, the grain sizes increase with the increase of the sintering temperature. This fact is connected with changes in dielectric properties. The maximum of the real part of permittivity ( ) and corresponding temperature (T m) shifts to higher values. The properties characteristic for the ferroelectric relaxors also yield to change. The ceramics sintered in higher temperature revealed lower frequency dispersion of and T m. It should also be noticed that the freezing temperature and the Burns temperature have changed. These results indicate that the behaviour of the relaxor ferroelectrics is weakened by the increase in the grain size.

Effect of Sb-dopant on phase transitions and selected properties of lead zirconate ceramics

Abstract The effect of antimony dopant on AFE–FE and FE–PE phase transitions in the lead zirconate ceramics was investigated by differential thermal analysis, pyroelectric and dielectric measurements. The decrease of these phase transition temperatures was observed without change in width of temperature range in which the intermediate ferroelectric phase occurs. This effect is different from this one observed in the PbZrO 3 ceramics with other heterovalent substitutions such as La 3+ , Ta 3+ and Nb 5+ previously studied. The effect of Sb-dopant on P r ( T ) and e ( T ) characteristics, and in particular low frequency dielectric dispersion in paraelectric phase is more detailed discussed.

Peculiarities of the pyroelectric effect and of the dielectric properties in Bi-doped Pb(Zr0.95Ti0.05)O3 ceramics

Abstract Unusual behaviour of the pyroelectric effect and some peculiarities of the dielectric characteristics in the vicinity of AFE↔FE phase transitions in Bi-doped Pb(Zr 0.95 Ti 0.05 )O 3 ceramics are confirmed. Two pyroelectric peaks are found both on heating and cooling through this phase transition. They occur at temperatures, which depend on the strength of the DC field, and on other conditions of the pre-poling procedure. The internal bias electric field associated with the metastable space charge polarisation is considered to be the reason for the observed peculiarities in the pyroelectric effect and dielectric properties.