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Na1-xLixNbO3 ceramics (for x = 0.08, 0.1, 0.2) were fabricated by the conventional solid state reaction method. The influence of LiNbO3 on the microstructure, electric, thermal properties of Na1-xLixNbO3 ceramics was studied and a significant influence of doped Li ions on the electrical properties was observed. The electrical properties were improved and are described as the best for x = 0.1 (near a morphotropic phase boundary) Na1–xLixNbO3 solid solutions. After crossing the morphotropic phase boundary for x = 0.2, the electric properties are getting worse. These types of solid compounds show some interesting properties suitable for practical applications.

The behavior of Ba1-xSrxTiO3 ceramics (x = 0, 0.3, 0.4 and 0.45) in both unpoled and poled states was studied using XRD, SEM, DSC and dielectric methods. The ceramics exhibit pure perovskite structure with tetragonal symmetry for x = 0, 0.3 and 0.4 and pseudocubic for x = 0.45. It was found that the substitution of SrTiO3 to BaTiO3 significantly influences the properties under investigation, leading to a shift of phase transitions and weakness of the dielectric and ferroelectric properties. This suggests that the effects are mainly due to the differences in ionic size between dopant and host ions and to the more covalent nature of the A–O bond following Sr2+ addition and that the former effect is predominant. It was shown that prior electric field poling decreases the disorder introduced by Sr modification through reinforced domains/polar regions ordering. [ABSTRACT FROM AUTHOR]

Ba1-xSrxTiO3 (BST) (x = 0, 0.1 and 0.2) ceramics were prepared by the solid-state reaction method and their structural, thermal and dielectric behavior was studied. The increasing concentration of Sr2+ ions leads to shift of Tc toward lower temperature. The results obtained are discussed in terms of microstructural/structural effects of Sr2+ incorporation into BaTiO3. It is shown that E-poling influences the properties under investigation. This includes modification of local structure, dielectric response and temperature of phase transformations. This could be the result of improvement by the electric field of the polarization ordering, previously disordered by the introduction of Sr2+ to BaTiO3. [ABSTRACT FROM AUTHOR]

The Mn-substituted NBT ceramics were prepared by the conventional ceramic fabrication technique. X-ray diffraction (XRD) studies indicated the formation of perovskite phase with rhombohedral symmetry and with small amount of second phase. It was found that 0.5mol% and 0.1mol% dopant concentration enhances piezoelectric coefficients of d33 and k33, increases the depolarization temperature Td and decreases the dielectric loss. Dielectric study showed the existence of a diffuse phase transition at Tm ≈ 320°C. It was shown that a prior electric field poling process changes the character of ϵ(T) and tanδ(T) functions, as well as shifts of Td and Tm to higher temperature. The effects are mainly caused by the reinforcement of polarization/domain ordering and by the change of content rhombohedral/tetragonal phases by electric field action. The results were discussed in terms of lattice distortion and change of defect concentration. [ABSTRACT FROM AUTHOR]

Crystals of PbTiO3 and 0.9PbTiO3-0.1(Na0.5Bi0.5)TiO3 were obtained by the flux growth method whereas crystals of (Na0.5Bi0.5) TiO3 were growth by the Czochralski method. Raman spectroscopy and polarized light microscopy were performed at room temperature. The Raman spectra of 0.9PbTiO3-0.1(Na0.5Bi0.5)TiO3 shown significant changes comparing to the base materials PbTiO3 and (Na0.5Bi0.5)TiO3. A domain structure was investigated by use polarized light microscopy. Dielectric permittivity measurements were carried out in the temperature range from 20°C to 550°C and a frequency from 1 kHz to 1 MHz. These showed higher dielectric permittivity for the crystals 0.9PbTiO3 -0.1(Na0.5Bi0.5)TiO3 than the source materials PbTiO3 and (Na0.5Bi0.5)TiO3. The high value of dielectric constant makes it possible to applied 0.9PbTiO3-0.1(Na0.5Bi0.5)TiO3 as efficient dielectric medium in a capacitors. The small size of the domain structure with the easy possibility of switching by application of an external electric field, give opportunities to apply these materials to FRAM memory applications. Moreover, the high sensitivity of these materials to the surrounding gases e.g. ammonia, chlorine, hydrogen, etc., allows the construction of sensor devices. [ABSTRACT FROM AUTHOR]

We investigated the influence of uniaxial pressure (0-1000 bars) applied parallelly or perpendicularly to the ac or dc electric field (in a one-dimensional or two-dimensional manner) on dielectric and ferroelectric properties of selected soft and hybrid-doped PZT ceramics (1 mol. % Gd, 1 mol. % La and 1 mol. % (La+Fe)-doped Pb(Zr0.54Ti0.46) O3). Applying uniaxial pressure leads to a reduction of the peak intensity of the electric permittivity (&eh;), of the frequency dispersion, and of the dielectric hysteresis. The peak intensity of &eh; becomes diffused and shifts to a higher temperatures with increasing pressure. Simultaneous application of uniaxial pressure and dc electric field (perpendicular to each other) in the poling process implies in improvement of the ferroelectric properties, indicating a new possibility for poling materials with a high coercive field and/or high electric conductivity. It was also found that simultaneous application of uniaxial pressure and dc electric field (perpendicular to each other) allowed observation of the space charge in the depolarization process. The electrostrictive coefficient Q11 and differential permittivity were evaluated from obtained data. Our results show that applying uniaxial pressure induces similar effects as increasing the Ti-ion concentration in the PZT system. We interpreted our results based on the Cochran soft-mode and domain switching processes under the action of pressure. [ABSTRACT FROM AUTHOR]

Influence of uniaxial pressure (0–1000 bars) applied parallel to or perpendicularly to the ac or dc electric field (in one-dimensional or two-dimensional manner) on dielectric and ferroelectric properties of hard lead zirconate titanate (PZT) ceramics were investigated. The experimental results revealed that applying uniaxial pressure leads to a reduction in the peak intensity of the electric permittivity ([variant_greek_epsilon]), of the frequency dispersion as well as of the dielectric hysteresis. Moreover, with increasing pressure the peak intensity of [variant_greek_epsilon] becomes diffused and shifts to a higher temperature. It was also found that simultaneous application of uniaxial pressure and electric field (perpendicular to each other) in the poling process improves the ferroelectric properties. This indeed indicates new possibility for poling materials with a high coercive field and/or high electric conductivity. The effects of uniaxial load are weaker than that obtained for soft PZT ceramics. It was concluded that applying uniaxial pressure induces similar effects as increasing the Ti ion concentration in PZT system. The obtained results were interpreted through Cochran soft mode and domain switching processes under applying of pressure. [ABSTRACT FROM AUTHOR]

Along with the development of engineering construction techniques, the interest in the issue of fastenings increases. In the construction of new facilities as well as in renovation works, a wide range of fasteners is currently used, enabling quick connections and safe fastening of various types of structural and installation elements. This progress is particularly visible in fixings made in concrete substrates. During assembly and during operation, the fasteners are subject to the influence of many external factors that may significantly affect their load capacity. Such factors include the type and nature of the load to be transferred, the strength and condition of the substrate, the temperature at which the fasteners will be installed and used. The technical parameters of fasteners determined by means of theoretical calculations still do not provide adequate accuracy, so that this method can be used to determine their impact on the behaviour of fasteners during their long-term operation. Therefore, their experimental verification is still required. In the countries of the European Union, the development of the rules for the use and assessment of expansion and bonded fasteners has been entrusted to the European Organization for Technical Assessment - EOTA. This organization groups bodies authorized by EU Member States to provide European technical assessments on the terms set out in Regulation No. 305/2011 (CPR) 2013. The current list of EOTA guidelines for expansion and bonded anchors used in the construction industry, specifying the basis for their use as well as standards for the design of fasteners. The scope and methods of fastener testing are presented in the EOTA guidelines. The purpose of these tests is to determine whether the behavior of the fasteners during their use will be safe and effective, taking into account the unfavourable conditions that can be encountered both during its installation and use. The publication will present the basic structural properties of fasteners made in drilled holes in concrete substrates reinforced with steel and polypropylene fibres.

The influence of uniaxial pressure (0 –1100 bars) applied parallel to the ac and dc electric field on the dielectric and ferroelectric properties of soft and hard PZT ceramics was studied in the temperature range from room temperature to 500°C. The results show that applying uniaxial pressure leads to a reduction of the peak intensity of the electric permittivity (ε) and its frequency dispersion. The peak intensity of ε becomes diffused and shifts with increasing pressure. The effective electric field Eeff and electrostrictive coefficient Q11 were evaluated from the obtained data. We explained our results based on the Cochran soft-mode, dielectric relaxation and a combination of de-aging and domain resulting processes from pressure. [ABSTRACT FROM AUTHOR]

The (1−x)BT-xPZN (x = 0, 0.025, 0.075, 0.100 and 0.125) ceramics were sintered using the Spark Plasma Sintering technique. The influence of PZN substitution on thermal expansion and dielectric/ferroelectric behavior of these ceramics was analyzed. The coefficient of thermal expansion decreases and then increases after the introduction of PZN into Barium titanate (BT). The results point to the diffuseness nature of the phase transition in BT-PZN ceramics, also suggesting the presence of polar regions above the phase transition temperature from the tetragonal phase to the cubic one. [ABSTRACT FROM AUTHOR]

The ceramics of 0.95BaTiO3–0.05PbTiO3+Xwt.%CuO (X = 0.05, 0.1, 1, 3) were prepared by a solid phase reaction. The structural and morphology studies were carried out by means of X-ray diffraction technique (XRD) and scanning electron microscopy (SEM). It was found that CuO addition shifts two low-temperature transitions to higher temperatures. The increase of Cu ions concentration leads to a slight decrease of the Curie temperature. The enthalpy ΔH of the transition was estimated and discussed. Electrical properties of the sintered bodies were determined by electrical impedance spectroscopy (EIS) in temperature range 473–773 K. [ABSTRACT FROM AUTHOR]

Barium titanate BaTiO3 (BT) is one of the widely applied lead-free ferroelectric materials due to relatively high permittivity and low cost. Lead zinc-niobate Pb(Zn1/3Nb2/3)O3 (PZN) belongs to a class of disordered and inhomogeneous materials, i.e. is a relaxor. Low-lead (1-x)BT-xPZN ceramics (x = 0, 0.025, 0.05, 0.075, 0.1, 0.125 and 0.15) were prepared by two-step conventional oxide mixed sintering process. Thermal conductivity (κ) of these ceramics was measured for the first time (except for x = 0) from room temperature to 200 °C. It was shown that the thermal conductivity decreases with both decreasing temperature and with increasing PZN content. κ(T) curves show anomaly at Curie temperature, which is connected with change of specific heat. Obtained results indicated that thermal conductivity of investigated samples is mainly related to phonons scattering by lattice defects and by atomic mass fluctuation resulted from PZN incorporation to BT. [ABSTRACT FROM AUTHOR]