Narrow Results

This work emphasis on the competence of (100)-oriented PMN–PT buffer layered (0.68PbMg_1/3Nb_2/3O₃–0.32PbTiO₃ with Pb(Zr_0.3Ti_0.7)O₃/PbO_x buffer layer) and (001)-oriented PMN–PT (0.67PbMg_1/3Nb_2/3O₃–0.33PbTiO₃) for low grade thermal energy harvesting using Olsen cycle. Our analysis (based on well-reported experiments in literature) reveals that these films show colossal energy harnessing possibility. Both the films are found to have maximum harnessable energy densities (PMN–PT buffer layered: 8 MJ/m³; PMN–PT: 6.5 MJ/m³) in identical ambient conditions of 30–150°C and 0–600 kV/cm. This energy harnessing plausibility is found to be nearly five times higher than the previously reported values to date.

The BNT ceramic sample might be a good replacement for PZT piezoelectric in industrial applications, especially in energy harvesting from crystal vibrations. In order to enhance the performance of BNT ceramic, the solid solution was chosen by substitution with Ba${}^{\mathrm{\text{+2}}}$ at Morphtropic Phase Boundary (MPB). The BNT-$x$BT powders with $x=1$, 0.07, 0.06 and 0 were prepared by the hydrothermal method with average particle size (65–150nm) at (90${}^{\circ }$C/72h). The ceramic disc was sintered at (1150${}^{\circ }$C/4h) and showed excellent relative density of about 96%. The results of X-ray diffraction (XRD) confirmed the MPB for $x=0.06$ and 0.07, while the BNT had a rhombohedral structure and BT had a tetragonal structure. The dielectric measurements showed that BNT, BNT-7BT, BNT-6BT behave as the relaxator ferroelectric and showed a strong dependence on frequency, especially in the MPB region while BT behaves as a normal ferroelectric. Both the Curie temperature and depolarization temperature decrease at the MPB region and showed strong dependency on frequency.

Based on the variational principle, equations and boundary conditions for transverse steady vibrations of a bimorph consisting of a piezoelectric and piezomagnetic layers are obtained. The results of calculations of natural frequencies are compared with the finite element model of the device in ACELAN.

This paper reports the impact of the laser pulse repetition frequency on growth processes, morphological and electro-physical parameters of nanocrystalline LiNbO₃ thin films obtained by the pulsed laser deposition technique. It was found that the nucleation process in LiNbO₃ films could controllably change by increasing the laser pulse repetition frequency. The film obtained at the repetition frequency of 4 Hz consists of local islands and clusters with a diameter of 118.1 ± 5.9 nm. Nanocrystalline films, grown at the repetition frequency of 10 Hz, possess a continuous granular structure with a grain diameter of 235 ± 11.75 nm. Achieved results can be used for the development of promising “green” energy devices based on lead-free piezoelectric energy harvesters.

This work harmonizes the experimental and theoretical study of electrocaloric effect (ECE) in (Pb${}_{0.8}$Bi${}_{0.2})$(Zr${}_{0.52}$Ti${}_{0.48})$O₃ solid solution by optimizing sintering temperature. Bi${}^{3+}$-doped PbZr${}_{0.52}$Ti${}_{0.48}$O₃ solid solutions were synthesized by the conventional solid-state reaction method. Different samples were prepared by varying the sintering temperature. X-ray diffraction study confirms the crystalline nature of all the samples. An immense value of polarization has been acquired in the optimized sample. The maximum adiabatic temperature change of order 2.53 K with electrocaloric strength of 1.26 K mm kV${}^{-1}$ has been achieved experimentally. Whereas a comparatively close value of ECE has been acquired from the theoretical calculations using a phenomenological approach. Furthermore, a large value (218 mJ cm${}^{-3})$ of thermal energy conversion has been obtained using the Olsen cycle.

Antimony sulfoiodide (SbSI) is a highly efficient energy conversion piezoelectric material. We obtained SbSI doped with tin (II) ions according to the formula Sb${}_{1-x}$Sn_xSI${}_{1-x}$ ($x=0.01$–0.1). This heterovalent doping has been performed by the novel method of synthesis in an aqueous solution. The introduction of tin cations leads to a material Curie point increase of more than 10K. The samples containing 5mol.% of the dopant possess the best piezoelectric properties: piezomodule $d_{33}\sim 750$pC/N, dielectric constant at a frequency of 1kHz — 1758, dielectric loss tangent — 0.054, and piezosensitivity — 50mV×m/N. Thus, tin-doped SbSI is a promising material for highly efficient electromechanical transducers and sensors.

This paper deals with distributed state estimation problem for discrete time-varying systems over binary sensor networks, where every binary sensor is equipped with an energy harvester. The input of every binary sensor considers the randomly occurring missing measurements. The differences between the real and estimated inputs of binary sensor are employed to derive useful information in order to address the insufficient information for estimation purpose. The information from neighboring nodes is transmitted only if its energy level is positive, where a random variable is introduced to formulate the energy level. By means of the available information, distributed estimator is constructed for each binary sensor and the desirable performance constraints is given for the dynamic characteristics of estimation errors within a finite time horizon. Sufficient conditions are established for the existence of desired distribution estimation quantities through local performance analysis methods. Also, the desired distributed estimator gains are calculated recursively, which means the desirable scalability. Ultimately, the viability and efficiency of the distributed scheme are exhibited through a practical illustration.