Fabrication and Characterization of Optically Transparent PVDF Films Embedded with Gold Nanoparticles

Polyvinylidene fluoride is a piezoelectric polymer that can be cast into transparent thin films. New properties can be introduced by embedding nanoparticles in this polymer, making it an excellent platform for flexible and tunable electronic and optoelectronic devices. We develop a recipe for embedding plasmonic gold nanoparticles into these films while maintaining their transparency as an initial step to activate optical response in the film. We characterize films made under different poling conditions with and without nanoparticle inclusions using X-ray diffraction. We find that the inclusion of gold nanoparticles screens the poling field and has a sizable effect on the phase of the produced films.

Nanoscale ordering of planar octupolar molecules for nonlinear optics at higher temperatures

We develop scenarios for orientational ordering of an in-plane system of small flat octupolar molecules at the low-concentration limit, aiming towards nonlinear-optical (NLO) applications at room temperatures. The octupoles interact with external electric poling fields and intermolecular interactions are neglected. Simple statistical-mechanics models are used to analyze the orientational order in the very weak poling limit, sufficient for retrieving the NLO signals owing to the high sensitivity of NLO detectors and measurement chains. Two scenarios are discussed. Firstly, the octupolar poling field is imparted by a system of point charges; the setup is subject to cell-related constraints imposed by mechanical strength and dielectric breakdown limit. The very weak octupolar order of benchmarking TATB molecules is shown to emerge at Helium temperatures. The second scenario addresses the dipoling of octupolar molecules with a small admixture of electric dipolar component. It requires a strong field regime to become effective at Nitrogen temperature range. An estimation of the nonlinear susceptibility coefficient matrix for both scenarios is done in the high-temperature (weak interaction) limit formalism. We argue that moderate modifications of the system like, e.g., an increase of the size of the octupole, accompanied by dipole-assisted octupoling, can increase the poling temperature above Nitrogen temperatures.

Nano-Domains Produced through a Two-Step Poling Technique in Lithium Niobate on Insulators

We proposed a two-step poling technique to fabricate nanoscale domains based on the anti-parallel polarization reversal effect in lithium niobate on insulator (LNOI). The anti-parallel polarization reversal is observed when lithium niobate thin film in LNOI is poled by applying a high voltage pulse through the conductive probe tip of atomic force microscope, which generates a donut-shaped domain structure with its domain polarization at the center being anti-parallel to the poling field. The donut-shaped domain is unstable and decays with a time scale of hours. With the two-step poling technique, the polarization of the donut-shaped domain can be reversed entirely, producing a stable dot domain with a size of tens of nanometers. Dot domains with diameter of the order of ∼30 nm were fabricated through the two-step poling technique. The results may be beneficial to domain-based applications such as ferroelectric domain memory.

Nature of polar state in 0.67BiFeO3–0.33BaTiO3

This study was conducted to further understand the nature of the polar state in 0.67BiFeO3–0.33BaTiO3 (0.67BF–0.33BT). A typical relaxor-type dielectric anomaly was observed (Tf = ~627 K, TB = ~820 K). The remnant polarization (Pr), maximum value of electrostrain (Sm) and magnitude strain at Ec in the bipolar mode (Sneg) increase clearly during heating (Pr, ~40 mC/cm2; Sm, 0.191 % under 40 kV/cm at 453 K). The first-cycle bipolar electrostrain loops indicate that the minimum strain on the negative side of the bipolar strain curves is negative. The slopes of the relative permittivity versus log frequency plots in unpoled (–21) and poled (–23) specimens are similar. The transition between the ergodic relaxor state and ferroelectric-like state does not involve a clear dielectric anomaly even in the poled specimen. Analyses based on the Rietveld refinement of XRD patterns, bright-field images and selected-area electron diffractions (SAED) demonstrate that the formation of the long-range ferroelectric domains is difficult under the poling field.

Highly Tunable Molecularly Doped Flexible Poly(dimethylsiloxane) Foam Piezoelectric Energy Harvesters

Despite considerable research interest in developing piezoelectric materials, little work has focused on the fundamental design of these materials from the ground up. Herein, we present a general, versatile method for producing tunable, flexible piezoelectric energy harvesters (PEHs) with excellent piezoelectric response. Using a poly(dimethylsiloxane) (PDMS) foam derived from a sugar template, we separate the electrical and mechanical properties of the PEH, thereby allowing us to optimize them separately. The electrical properties were tuned by varying the poling field, the polar dopant, and the dopant concentration. The mechanical properties were tuned by varying foam preparation and thus the compressive modulus. Through the careful tuning of these properties, we are able to achieve a maximum piezoelectric response of 153 pC/N—considerably higher than most other reported flexible PEHs. Combined with our previous work, we demonstrate that doping polymer foams with polar dopants is a highly general strategy and has the potential to lead to materials with considerably higher piezoelectric responses.

Highly Tunable Molecularly Doped Flexible Poly(dimethylsiloxane) Foam Piezoelectric Energy Harvesters

Despite considerable research interest in developing piezoelectric materials, little work has focused on the fundamental design of these materials from the ground up. Herein, we present a general, versatile method for producing tunable, flexible piezoelectric energy harvesters (PEHs) with excellent piezoelectric response. Using a poly(dimethylsiloxane) (PDMS) foam derived from a sugar template, we separate the electrical and mechanical properties of the PEH, thereby allowing us to optimize them separately. The electrical properties were tuned by varying the poling field, the polar dopant, and the dopant concentration. The mechanical properties were tuned by varying foam preparation and thus the compressive modulus. Through the careful tuning of these properties, we are able to achieve a maximum piezoelectric response of 153 pC/N—considerably higher than most other reported flexible PEHs. Combined with our previous work, we demonstrate that doping polymer foams with polar dopants is a highly general strategy and has the potential to lead to materials with considerably higher piezoelectric responses.

Highly Tunable Molecularly Doped Flexible Poly(dimethylsiloxane) Foam Piezoelectric Energy Harvesters

Despite considerable research interest in developing new piezoelectric materials, little work has focused on the fundamental design of these materials from the ground up. Herein, we present a general, versatile method for producing tunable, flexible piezoelectric energy harvesters (PEHs) with excellent piezoelectric response. Using a poly(dimethylsiloxane) (PDMS) foam derived from a sugar template, we separate the electrical and mechanical properties of the PEH, thereby allowing us to optimize them separately. The electrical properties were tuned by varying the poling field, the polar dopant, and the dopant concentration. The mechanical properties were tuned by varying foam preparation and thus the compressive modulus. Through the careful tuning of these properties, we are able to achieve a maximum piezoelectric response of 153 pC/N—considerably higher than most other reported flexible PEHs. Combined with our previous work, we demonstrate that doping polymer foams with polar dopants is a highly general strategy and has the potential to lead to materials with considerably higher piezoelectric responses.

Studies of dielectric and piezoelectric properties of PbTi0.8−x Te0.2GdxO3 nano ceramics prepared by high energy ball milling

Incorporation of Te and Gd were done based on the stoicheometric formula PbTi[Formula: see text] Te[Formula: see text]GdxO3 (PTTeG). TG characterization of green powder revealed the completion of solid state reaction at temperature 450∘ C. XRD of modified PTTeG powders milled for 10[Formula: see text]h was found most suitable as it gives pure single-phase tetragonal structure. Dielectric constant was found as 2543 at curie temperature of 480∘C in the case of 5[Formula: see text]wt.% of Gd in PTTeG. Piezoelectric Coefficient was found as 241 [Formula: see text] 10 [Formula: see text] C/N at 39[Formula: see text]Kv/cm of poling field. The results obtained were comparable and even better than so far reported in similar kind of materials.

Highly Tunable Molecularly Doped Flexible Poly(dimethylsiloxane) Foam Piezoelectric Energy Harvesters

Despite considerable research interest in developing new piezoelectric materials, little work has focused on the fundamental design of these materials from the ground up. Herein, we present a general, versatile method for producing tunable, flexible piezoelectric energy harvesters (PEHs) with excellent piezoelectric response. Using a poly(dimethylsiloxane) (PDMS) foam derived from a sugar template, we separate the electrical and mechanical properties of the PEH, thereby allowing us to optimize them separately. The electrical properties were tuned by varying the poling field, the polar dopant, and the dopant concentration. The mechanical properties were tuned by varying foam preparation and thus the compressive modulus. Through the careful tuning of these properties, we are able to achieve a maximum piezoelectric response of 153 pC/N—considerably higher than most other reported flexible PEHs. Combined with our previous work, we demonstrate that doping polymer foams with polar dopants is a highly general strategy and has the potential to lead to materials with considerably higher piezoelectric responses.