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Gurskii L.I.,Belarusian State University of Informatics and Radioelectronics | Macutkevic J.,Vilnius University | Banys J.,Vilnius University | Poddubskaya A.,Institute for Nuclear Problems | And 2 more authors.
Physica Status Solidi (C) Current Topics in Solid State Physics | Year: 2013

Ceramic piezomaterials based on Pb0.75Ba0.15Zr0.53Ti0.47O3 (PBZT) system are characterized by high values of the ferroelectric Curie temperature and polarization. They have widespread applications in electromechanical and electroacoustic transducers, bandwidth filters, transformers, frequency stabilized resonators, etc. Preparation of PBZT composites with nano-inclusions of Cu and Ni have been carried out by a complex powder technology including metallization procedures which were performed by the well-known chemical deposition method from standard solutions of copper and nickel. Studies of hydrostatic density and porosity of obtained samples as well as their microstructural investigations have yielded a larger density of PBZT-metal composites (5.3 - 7.3 g/cm3) as compared with pure PBZT (4.7 g/cm3). Measurements of dielectric properties of samples in the frequency range from 20 Hz - 1 MHz have shown that the Curie temperature increases in PBZT (Ni) and decreases in PBZT(Cu) in comparison with pure PBZT. The complex dielectric permittivity of all investigated composites at higher temperatures and low frequencies is mainly caused by the high electrical conductivity. Only at the highest frequency used (1 MHz) the real part of the complex permittivity is caused by a resonant soft mode and could be fitted with the Curie-Weiss law. The activation energy of ferroelectric domain mobility in PBZT (Cu, Ni) composites is lower than in pure PBZT. This can be explained by a decrease of the domain size in composites. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Shut V.N.,Institute of Technical Acoustics | Syrtsov S.R.,Institute of Technical Acoustics | Trublovsky V.L.,Institute of Technical Acoustics | Il'Yuschenko D.A.,Institute of Technical Acoustics | Troyanchuk I.O.,Scientific Practical Materials Research Center
Ferroelectrics | Year: 2014

Ceramics of composition Ba1-xLaxTiO3 were prepared by two-step sintering method. The average grain size of the sintered samples were 300 nm (for x = 0.025) and 500 nm (for x = 0.05). Relative densities of these samples were 92.8%TD and 92.3%TD. Despite the small grain size, the magnitude of dielectric permittivity of ceramics has higher value in comparison with coarse-grained materials sintered by standard technology (with grain size >1 μm). © 2014 Copyright Taylor & Francis Group, LLC. Source

Muller-Trapet M.,Institute of Technical Acoustics | Dietrich P.,Institute of Technical Acoustics | Vorlander M.,Institute of Technical Acoustics
Noise Control Engineering Journal | Year: 2011

In a previous publication by the authors, a virtual measurement environment for sound-source localization on vibrating structures was presented. Based on surface velocity data obtained from Laser-Scanning-Vibrometry measurements, the Boundary-Element-Method (BEM) is used to simulate the sound radiation from a vibrating plate towards a microphone array under ideal conditions. The advantage of this approach is that the measurement conditions can be perfectly controlled and real sources can be considered, without restrictions on the type of source. The virtual measurement environment will now be used to investigate the effect of some of the uncertainties that can be encountered during beamforming measurements. For the most common planar array geometries, the beamforming source maps will be calculated for varying Signal-to-Noise Ratios (SNR) and different array imperfections (uncertainties in the microphone locations and deviation from the omni-directional directivity pattern of the microphones). As a measure of comparison, the two-dimensional normalized cross-correlation coefficient between the ideal source map and the source map with added uncertainties will be evaluated and discussed. © 2011 Institute of Noise Control Engineering. Source

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