Piezoelectric Voltage Constant and Sensitivity Enhancements Through Phase Boundary Structure Control of Lead-free (K,Na)NbO3-based ceramics

The piezoelectric voltage constant (g33) is a material parameter critical to piezoelectric voltage-type sensors for detecting vibrations or strains. Here, we report a lead-free (K,Na)NbO3 (KNN)-based piezoelectric accelerometer with voltage sensitivity enhanced by taking advantage of a high g33. To achieve a high g33, the magnitudes of piezoelectric charge constant d33 and dielectric permittivity er of KNN were best coupled by manipulating the intrinsic polymorphic phase boundaries effectively with the help of Bi-based perovskite oxide additives. For the KNN composition that derives benefit from the combination of er and d33, the value of g33 was found to be 46.9 ´ 10-3 V·m/N, which is significantly higher than those (20 - 30 ´ 10−3 V·m/N) found in well-known polycrystalline lead-based ceramics including commercial Pb(Zr,Ti)O3 (PZT). Finally, the accelerometer sensor prototype built using the modified KNN composition demonstrated higher voltage sensitivity (183 mV/g) when measuring vibrations, showing a 29% increase against the PZT-based sensor (142 mV/g).

Remarkable piezoelectric properties in thin films of cellulose nanofibers after electrochemical poling

Internet-of-everything (IoE) is defined as networked connections of things, people, data and processes. IoE nodes, preferably shaped as printed flexible systems, serves as the frontier outpost of the Internet and comprises devices to record and regulate states and functions. To power distributed IoE nodes in an ecofriendly manner, technology to scavenge energy from ambience and self-powered devices are developed. For this, piezoelectricity is regarded as a key-property, however current technology typically based on polyvinylidene difluoride (PVDF) co-polymers, are expensive and produced via toxic protocols. We report piezoelectric characteristics of electrochemically poled cellulose nanofiber (CNFs) thin films processed from water dispersions. Poling these films at humid conditions cause breaking and reorientation of CNF segments, which results in enhanced crystal alignment rendering the resulting material piezoelectric. Generators based on poled CNF show similar piezoelectric voltage and coefficient, here measured to d33 = 46 pm/V, as for devices including PVDF copolymer layers of similar thickness. Our findings promise for low cost and printable ecofriendly piezoelectric-powered IoE nodes.

Ab-Initio Predictions of the Energy Harvesting Performance of L-Arginine and L-Valine Single Crystals

Biological piezoelectric materials are beginning to gain attention for their huge potential as eco-friendly energy harvesting materials. In particular, simple amino acid and peptide crystal assemblies are demonstrating large voltage outputs under applied force, and high sensitivity when detecting vibrations. Here we utilise Density Functional Theory (DFT) calculations to quantitatively predict the energy harvesting properties of two understudied proteinogenic amino acid crystals: L-Arginine and L-Valine. The work highlights the ability of quantum mechanical calculations to screen crystals as high-performance energy harvesters, and demonstrates the capability of small biological crystals as eco-friendly piezoelectric materials. L-Arginine is predicted to have a maximum piezoelectric voltage constant of gij = 274 mV m/N, with a Young’s Modulus of E = 17.1 GPa. L-Valine has a maximum predicted piezoelectric voltage constant of gij = 62 mV m/N, with a calculated Young’s Modulus of E = 19.8 GPa.

Intrinsically Polar Piezoelectric Self-Assembled Oligopeptide Monolayers

<div><div><div><p>Flexible, bio-compatible piezoelectric materials are of considerable research interest for a variety of applications, but many suffer from low response or high cost to manufacture. Herein, novel piezoelectric force and touch sensors based on self-assembled monolayers of oligopeptides are presented which produce large piezoelectric voltage response and are easily manufactured without the need for electrical poling. While the devices generate modest piezoelectric charge constants (d33) of up to 9.8 pC N−1, they exhibit immense piezoelectric voltage constants (g33) up to 2 V m N−1. Furthermore, a flexible device prototype is demonstrated that produces open-circuit voltages of nearly 6 V under gentle bending motion. Improvements in peptide selection and device construction promise to further improve the already outstanding voltage response and open the door to numerous practical applications.</p></div></div></div>

Intrinsically Polar Piezoelectric Self-Assembled Oligopeptide Monolayers

<div><div><div><p>Flexible, bio-compatible piezoelectric materials are of considerable research interest for a variety of applications, but many suffer from low response or high cost to manufacture. Herein, novel piezoelectric force and touch sensors based on self-assembled monolayers of oligopeptides are presented which produce large piezoelectric voltage response and are easily manufactured without the need for electrical poling. While the devices generate modest piezoelectric charge constants (d33) of up to 9.8 pC N−1, they exhibit immense piezoelectric voltage constants (g33) up to 2 V m N−1. Furthermore, a flexible device prototype is demonstrated that produces open-circuit voltages of nearly 6 V under gentle bending motion. Improvements in peptide selection and device construction promise to further improve the already outstanding voltage response and open the door to numerous practical applications.</p></div></div></div>

Large piezoelectric voltage coefficient in aluminate-sodalite-type improper ferroelectric oxide

Dielectric and piezoelectric properties of aluminate-sodalite-type oxides, (Ca1-xSrx)8[AlO2]12{MoO4}2 ((CS)AM-x) have been investigated in the present study. The variation of dielectric anomalies clarifies the phase diagram of (CS)AM-x over a composition...