Electrical Conductivity and Phase Transitions in Ferroelectric Solid Solutions Li0.17Na0.83ТауNb1-уO3 (y = 0 – 0.5) in High Pressure

Ferroelectric ceramic solid solutions LixNa1-xTayNb1-yO3 (х = 0.17; у = 0 – 0.5) with the perovskite structure have been obtained by the thermobaric synthesis method. Particularities of their microstructure, elastic properties, electrical conductivity and permittivity have been researched. It has been established that an increase in the thermobaric synthesis temperature leads to a decrease in the Young’s modulus value. Specific static conductivity values have been determined; charge carrier activation enthalpies На have been calculated. The Curie temperature of the samples has been determined to decrease with an increase in tantalum content. A Ferroelectric ceramic solid solution Li0.17Na0.83Ta0.1Nb0.9O3 was shown to undergo four structure phase transitions in the temperature range 300-820 К. A Li0.17Na0.83Ta0.1Nb0.9O3 has been shown to be a high temperature superionic. Possible mechanisms of the detected phenomena are discussed.

Structural, Phase Transition, Morphological, Optical and Dielectric Properties of Lead Free(1-x)(Na0.99K0.01)(Nb0.95Sb0.05)O3-xBaTiO3 Solid Solutions

In this work, lead free (1-x)(Na0.99K0.01)(Nb0.95Sb0.05)O3-xBaTiO3, where x=0.1, 0.2 ceramic solid solution systems were prepared via solid state sintering method. X-ray diffraction (XRD) reveals that the influence of Ba2+ on crystal structure of the NKNS-xBT (x=0.1, 0.2) solid solutions. PXRD analysis showed that Ba2+ addition into NKNS ceramics caused significant change in crystal symmetry from tetragonal to cubic. The surface morphology of the prepared ceramics were determined by scanning electron microscopic (SEM) measurements and revealed that the uniform distribution of grains. Energy band gap were determined by UV-visible absorption spectrophotometer. Dielectric measurements show the maximum dielectric constant (ε~3044) and temperature (Tm~120°C) at 1 kHz.

Application of a Preisach Hysteresis Model to the Evaluation of PMN-PT Ceramics Properties

The work presents enhanced, relatively new iterative method for obtaining the classical Preisach distribution from a single, saturated hysteresis loop. As the material for research and analysis, the ceramic solid solution (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (x = 0 to 0.40) was selected. Distributions were obtained for (1-x)PMN-xPT ceramics as a function of PT content, and function of temperature, for a selected composition from the morphotropic phase boundary region. The paper also proposes a mathematical model of the Preisach distribution and the parameters of the distribution were calculated. The typical factors achievable directly from the hysteresis loop with a coefficients determined from the analytical Preisach model were compared.

Fabrication of 0.95BaTiO3-0.05Pb(Mg1/3Nb2/3)O3 Ceramics by Conventional Solid State Reaction Method

The possibility to obtain of ceramic solid solution between barium titanate and lead magnesium niobate by two-step sintering technique through conventional solid-state reaction method has been investigated. In the first step MgNb2O6 has been synthesized. In the second step 0.95BaTiO3-0.05Pb(Mg1/3Nb2/3)O3 has been obtained using MgNb2O6, PbO and BaTiO3. The two-step sintering technique is effective for the synthesized of 0.95BaTiO3-0.05Pb(Mg1/3Nb2/3)O3 ceramics. Single-phase (pyrochlore-free) ceramics with perovskite phase were obtained.