Jee-Su Kim

Lead magnesium tantalate-lead titanate perovskite ceramic system : preparation and characterization

Abstract Selected composition ceramics in the Pb(Mg 1/3 Ta 2/3 )O 3 –PbTiO 3 system were prepared and characterized. Phases developed in the B-site precursor and perovskite systems were examined by X-ray diffraction. Dependencies of the lattice constants and dielectric properties upon composition were investigated. Dielectric relaxation modes in the paraelectric temperature range were quantitatively analyzed in terms of diffuseness parameters. Ferroelectric hysteresis responses with changes in temperature were monitored. Dielectric maximum temperatures in the system increased steadily with increasing PbTiO 3 concentration, whereas maximum dielectric constants were higher at intermediate compositions.

Dielectric properties of Pb(Zn1∕3Ta2∕3)O3-modified Pb(Mg1∕3Nb2∕3)O3-PbTiO3 perovskite ceramics

Perovskite solid solutions of 0.2Pb(Zn1∕3Ta2∕3)O3-0.8Pb[(Mg1∕3Nb2∕3),Ti]O3 were synthesized and characterized. Developed structures and the crystallographic symmetries as well as the lattice parameters were investigated. Weak-field dielectric constant and loss values of the ceramics were measured as functions of composition, temperature, and frequency. The dielectric constant spectra in the paraelectric temperature region were also analyzed in terms of diffuseness in the phase transition modes. The results were compared with other substituents of Pb(Mg1∕3Ta2∕3)O3, Pb(Mg1∕3Nb2∕3)O3, as well as Pb(Zn1∕3Nb2∕3)O3.

Mg substitutions for Zn in 0.8Pb[Zn1/3(Ta,Nb)2/3]O3–0.2PbTiO3 ceramics and dielectric properties

Abstract Systematic substitutions of Mg for Zn in 20 mol% PbTiO 3 -added Pb[Zn 1/3 (Ta,Nb) 2/3 ]O 3 (with different fractions of Ta and Nb) were attempted. The perovskite developments turned out to be promoted significantly by the Mg replacement. Values of the maximum dielectric constant and corresponding temperature were higher at higher Nb concentration. Frequency-dependent dielectric dispersion (with diffuse modes in the phase transition) was observed in the entire ceramics, except for the compositions without any Mg substitution. Microstructure observation results were generally consistent with the perovskite formation yields (determined by X-ray analysis).