Design, Modeling, and Simulation of Two-Piece Trapezoidal Piezoelectric Devices for Sensing and Energy Harvesting

The objective of the research is to design a high power energy harvester device through a two-piece trapezoidal geometry approach. The performance of the composite two-piece trapezoidal piezoelectric PZT-PZN polycrystalline ceramic material is simulated using COMSOL Multiphysics. Results are analysed using the series configuration of a two-piece trapezoidal composite bimorph cantilever which vibrates at the first fundamental frequency. The two-piece trapezoidal composite beam designs resulted in a full-width half-maximum electric power bandwidth of 2.5 Hz while providing an electric power density of 16.81 mW/cm3 with a resistive load of 0.08 MΩ. The authors believe that these results could help design a piezoelectric energy harvester to provide local energy source which provides high electric power output.

Stress Concentration and Distribution at Triple Junction Pores of Three-Fold Symmetry in Ceramics

The stress concentration and distribution around a triple-junction pore of three-fold symmetry in a polycrystalline ceramic material is considered. The perturbation method in the theory of plane elasticity is used to solve the problem of a nearly circular pore of three-fold symmetry under remote loading in the first approximation. The solution was specified to the uniaxial tension of convex and concave rounded triangular pores. The stress concentration on the pore surface and the stress distribution in vicinity of the pore along its symmetry axes are studied and discussed in detail. The numerical results, issued from the first-order approximation analytical solution, are compared with those of finite-element calculations.

Modeling, Simulation and Optimization of Piezoelectric Bimorph Transducer for Broadband Vibration Energy Harvesting in Multi-Beam and Trapezoidal Approach

The objective of the research is to design a broadband energy harvester device through the multi-beam approach and non-linear trapezoidal geometry approach. The performance of the composite piezoelectric PZT-PZN polycrystalline ceramic material is simulated using COMSOL Multiphysics, and results are compared using series configuration of a composite bimorph energy harvester which vibrates at its 1st fundamental frequency. We chose a five cantilever multibeam harvester to demonstrate that individual fundamental modes of the beams can achieve a broader frequency band and generate power. Authors also show that composite trapezoidal beam design leads to high power density broadband frequency response. The multibeam approach resulted in broader bandwidth of 18 Hz while generating a power density of 0.0913 mW/cm3 whereas the trapezoidal shape generated 2.3 – 2.5 mW/cm3 with a bandwidth of 4 to 6 Hz. Authors believe that these results could help design broadband energy harvesters to enhance power density as well as bandwidth.

Characterization of Bi6Fe2Ti3O18 Ceramics with Impedance Spectroscopy

In the present research the tool of impedance spectroscopy was utilized to characterize dielectric behavior of Aurivillius-type ceramics of Bi6Fe2Ti3O18 composition fabricated by hot pressing method from the stoichiometric mixture of oxides Bi2O3, TiO2 and Fe2O3. Impedance spectroscopy was applied to characterize dielectric response of bulk, grain boundary, and material/electrode interfaces of the fabricated polycrystalline ceramic material at both room and elevated temperature. The Kramers-Kronig data validation test was employed in the impedance data analysis. Experimental data were fitted using the CNLS fitting method. Agreement between experimental and simulated data was established.

TEM Analysis of an Alumina Bicrystal Section Using a Fib

Grain boundary migration (GBM) during the sintering and densification of a polycrystalline ceramic material occurs as a result of mass transport across an interface. When there is a liquid film present, either due to additives used for liquid-phase sintering or unavoidable impurities in the material, the mass transport can be visualized in terms of dissolving material from one grain and precipitating it on another. in order to study the effects of crystallography on GBM in the presence of a liquid phase, alumina bicrystals have been fabricated with anorthite (CaA12Si208) glass films at the interface. The alumina-anorthite system in a bicrystal geometry is used because the pseudo-binary phase diagram of the system is well known, the bicrystal geometry allows for control over the original interface misorientation, and the glassy phase of anorthite is the most commonly occurring glass in commercially used alumina.Fig. 1 is a secondary-electron SEM image of an alumina bicrystal recorded using a field-emission SEM (Hitachi S900) operating at 5 kV.

Formation of patterned microstructures of polycrystalline ceramics from precursor polymers using micromolding in capillaries

Micromolding in capillaries has been used to generate patterned microstructures of ZrO2 or SnO2 from its polymeric precursor. After patterning, the amorphous precursor was converted into the desired polycrystalline ceramic material by calcination in air at 460 °C. The final phase for each ceramic material was determined by powder x-ray diffraction. The shrinkage of the precursor material during pyrolysis was investigated by scanning electron microscopy and atomic force microscopy. These ceramic microstructures could be either supported on solid substrates or released as freestanding fibers and membranes. Their lateral dimensions could be as small as approximately 500 nm.