W. Śmiga

The Electrical Properties of Ba1-ySryZrxTi1-xO3 Solid Solution

A lead-free solid solution Ba0.80Sr0.20Ti0.75Zr0.25O3 was prepared by a conventional technology. The structure and morphology of investgated samples were characterised by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The studies of electric conductivity were performed depending on temperature and frequency of electric measuring field. The activation energy was calculated from the Arrhenius plots.

Structural and Mechanical Properties of Ceramic Solid Solutions Na1-xLixNbO3 for x < 0.06

Microstructure, material constants (Young modulus E, shear modulus G, Poisson ratio v), Vickers hardness HV and fracture toughness K Ic of polycrystalline ferroelectrics Na1 - xLixNbO 3 for x ≤ 0.06 were investigated to determine their dependence on lithium concentration. It has been shown that the Young modulus decreases with the increase of lithium concentration in NaNbO 3 up to 2mol-percent. The highest variations of mechanical properties appearing for Na1 - xLixNbO 3 at 2mol-percent concentration of lithium can be related to the occurence of a morphotropic limit for this concentration. The investigations of mechanical properties resulted in the possibility to asses the usability of this material for transducers and sensors that could work under load.

Ultrasonication as a Method of Investigation of the Mechanical Properties of Doped Hafnium Barium Titanate

The purpose of this study was to fabricate dense ceramic specimens from the system of BaTiO3-BaHfO3 and then to perform mechanical tests. The effect of Hf content on a microstructure and mechanical properties of the BaTiO3-BaHfO3 solid solution was investigated at room temperature. To determine the elastic constants (the Young′s modulus E, the shear modulus G, bulk modulus K and the Poisson′s ratio v) of BaHfxTi1-xO3 a method of measurement of the longitudinal (VL ) and transverse (VT ) ultrasonic wave velocities for this type of material was developed.

Temperature and time changes electric permittivity in sodium niobate

Abstract Temperature and time dependencies of electric permittivity of sodium niobate have been measured. The dispersion and time changes of electric permittivity for NaNbO3 ceramic has been observed. Results of this investigations indicate for complex processes occuring in this material.

Dielectric properties of Li0.003Na0.997NbO3 ceramics

Abstract Temperature, frequency and time dependencies of dielectric permittivity and pyroelectric current of Li0.003Na0.997NbO3 ceramics have been presented. Investigation of the pyroeffect reveals the existence of the local dipoles in a temperature range above the temperature of the maximum of the dielectric permittivity, Tm . The observed dispersion of the dielectric permittivity for this material and its time dependence, can be connected with the existence of these dipoles. The occurrence of these dipoles can be associated with a large local deformation accompanying the substitution of individual Li-by Na-ions and with imperfections of the polycrystal.

STRONTIUM CONCENTRATION DEPENDENCE OF SELECTED STRUCTURAL AND MECHANICAL PROPERTIES OF POLYCRYSTALLINE Ba1−XSrXTiO3

ABSTRACT Microstructure and material constants such as Young modulus E, shear modulus G, Poisson ratioν of polycrystalline ferroelectric materials Ba1-xSrxTiO3 for 0≤x≤0.4 were investigated to determine their dependence on strontium concentration. The performed investigations showed that the material is chemically homogeneous. It was found that the strontium concentration had no significant influence on the grain size. The highest value of Youngs modulus is observed for Ba0.6Sr0.4TiO3 sample. The performed investigations of mechanical properties made it possible to evaluate the usability of this material for manufacturing transducers and sensors which could work under load.

Physical Properties of Ba0.95Pb0.05TiO3+0.1%Co2O3

The single-phase perovskite structure of the Ba0.95Pb0.05TiO3+0.1%Co2O3 ceramics was confirmed by the X-ray diffraction method. Microstructural studies revealed that the samples were of good quality and chemically homogeneous. The thermal behaviour of ceramics was studied using the in situ high-temperature X-ray synchrotron powder diffraction investigation. The energy gap of about 3.2 eV was estimated using a reflectance spectroscopy. Measurements showed the influence of Pb and Co on the character of phase transition in the BaTiO3 structure. The results were compared to the ones obtained for pure BaTiO3.

Characterization of Dielectric Anomaly in Solid Solution Based on BaTiO3

The influence of Zr doping on a structure and dielectric properties of Ba0.8Sr0.2TiO3 were studied. For this purpose Ba0.8Sr0.2Ti0.75Zr0.25O3 ceramics were obtained by a conventional method and were determined by an X-ray diffraction (XRD) and scanning electron microscopy (SEM) for crystallographic, surface morphological and compositional studies. The temperature and frequency dependence of dielectric permittivity were studied in the temperature range from 150 to 500 K and the frequency between 20 Hz and 1000000 Hz. The thermal behavior of the Ba0.8Sr0.2Ti0.75Zr0.25O3 ceramics were also studied using Differential Scanning Calorimetry. A diffusivity coefficient γ was calculated.

The piezoelectric effect in Pb[(Fe1/3Sb2/3) x Ti y Zr z ]O3 ceramics

The piezoelectric properties of Pb[(Fe1/3Sb2/3) x Ti y Zr z ]O3 with x + y + z = 1, x = 0.1, y = 0.43–0.48 ceramics have been investigated over a broad temperature range using a resonance technique. The influence of modification of PZT normal ferroelectric synthesized near the morphotropic phase boundary by a relaxor Pb(Fe1/3Sb2/3)O3 compound on its physical properties was studied. The coefficients s 11, k 31, and d 31 were calculated from the parameters characterizing the behavior of damped harmonic oscillator in the vicinity of the piezoelectric resonance. Several anomalies of the piezoelectric coefficients have been found in the temperature range 300–600 K. Two diffuse phase transitions were observed in Pb[(Fe1/3Sb2/3) x Ti y Zr z ]O3. The anomaly near 530 K for y = 0.43 is responsible for the transition from the rhombohedral phase to the tetragonal one. For y > 0.44 this transition is found to be very diffuse and the coexistence of rhombohedral and tetragonal phases occurs. The observation of low piezoelectric activity confirms the existence of polar regions in Pb[(Fe1/3Sb2/3) x Ti y Zr z ]O3 above T m.

Germanium modified BaTiO3 as a promising electroceramics

ABSTRACT The polycrystalline sample of BaTi0.95Ge0.05O3 was prepared by solid-phase reaction using a conventional method. The morphology of investigated sample was characterised by scanning electron microscopy (SEM). The results allowed to determining the stoichiometry of the material and evaluate their microstructure. High quality samples were investigated, the grains are well shaped without of a glassy phase. The dielectric properties of the BaTi0.95Ge0.05O3 ceramics were determined. The results were compared with these ones obtained for pure BaTiO3. The obtained data indicated that the substitution of Ge+4 ions had an influence on the values of the real (ϵ′) and imaginary (ϵ″) parts of electric permittivity.