Estimating the true piezoelectric properties of BiFeO₃ from measurements on BiFeO₃-PVDF terpolymer composites

BiFeO₃ is an interesting multiferroic material with potential use in sensors and transducers. However, the high coercive field and low dielectric strength of this material make the poling process extremely difficult. Poling becomes a lot easier if the ceramic particles are incorporated in a non-conductive polymer with comparable...

Effect of topological imperfections on the electro-mechanical properties of structured piezoelectric particulate composites

A novel method based on the Virtual Particle Mori–Tanaka (VPMT) is developed to predict the effective electro-elastic properties, d₃₃ and g33, of structured piezoelectric particulate composites with improved accuracy by means of a single parameter related to the spatial distribution of imperfectly aligned rod-like PZT particles....

Effect of particle contact on the electrical performance of NTC-epoxy composite thermistors

As demand rises for flexible electronics, traditionally prepared sintered ceramic sensors must be transformed into fully new sensor materials that can bend and flex in use and integration. Negative temperature coefficient of resistance (NTC) ceramic thermistors are preferred temperature sensors for their high accuracy and excellent stability,...

Flexible, printed, Pb-free piezo-composites for haptic feedback systems

While most of the work on piezoelectric composites focuses on methods to reduce the dielectric constant of the composite (for better sensor and energy harvesting performance), for haptic feedback and actuator applications the opposite is desirable. We present here a study of the effect of adding a second ceramic phase (BaTiO3 nanoparticles)...

Flexible Lead-Free Piezoelectric Composite Materials for Energy Harvesting Applications

Vibrational piezoelectric energy harvesters are being investigated to replace batteries in embedded sensor systems. The energy density that can be harvested depends on the figure of merit, d₃₃g₃₃, where d₃₃ and g₃₃ are the piezoelectric charge and voltage coefficient. Commonly used piezoelectric...

The effect of the intrinsic electrical matrix conductivity on the piezoelectric charge constant of piezoelectric composites

Polymer-piezoceramic composites have drawn a lot of attention for sensor and energy harvesting applications. Poling such materials can be difficult due to the electric field getting mostly distributed over the low dielectric constant matrix. During this process, the electrical matrix conductivity plays a vital role. This work shows how two...

Setup for EMI Shielding Effectiveness Tests of Electrically Conductive Polymer Composites at Frequencies up to 3.0 GHz

Conductive polymer composites have been receiving increased interest both from the scientific community and industry with a special focus on electromagnetic interference (EMI) shielding applications. In this paper, we present the design, EM wave simulation, and validation through S-parameters measurements of an EMI shielding effectiveness (SE...

Poling piezoelectric (K,Na,Li)NbO₃-polydimethylsiloxane composites

Composites of aligned (K,Na,Li)NbO₃ (KNLN) piezoceramic particles in a PDMS polymer matrix are presented as promising materials for flexible sensors and energy harvesters. Their ease of processing is matched with a relatively high damage tolerance and piezoelectric performance at low dielectric loss. To maximize piezoelectric...

Flexible Piezoelectric Touch Sensor by Alignment of Lead-Free Alkaline Niobate Microcubes in PDMS

A highly sensitive, lead-free, and flexible piezoelectric touch sensor is reported based on composite films of alkaline niobate K_0.485Na_0.485Li_0.03NbO₃ (KNLN) powders aligned in a polydimethylsiloxane (PDMS) matrix. KNLN powder is fabricated by solid-state sintering and consists of microcubes. The...

In-situ poling and structurization of piezoelectric particulate composites

Composites of lead zirconate titanate particles in an epoxy matrix are prepared in the form of 0–3 and quasi 1–3 with different ceramic volume contents from 10% to 50%. Two different processing routes are tested. Firstly a conventional dielectrophoretic structuring is used to induce a chain-like particle configuration, followed by curing the...