3 research outputs found
Defect-Induced Self-Poling in a W<sub>18</sub>O<sub>49</sub>/PVDF Piezoelectric Energy Harvester
W18O49 nanostructures, previously used for
electrocatalysis, energy storage, electrochromic, and gas sensing
applications, are incorporated in poly(vinylidene fluoride) (PVDF)
in this work for mechanical energy-harvesting applications. X-ray
diffraction spectroscopy (XRD), high-resolution transmission electron
microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), Fourier
transform infrared spectroscopy (FTIR), Raman spectroscopy, differential
scanning calorimetry (DSC), and the polarization-electric (P-E) field
loop test prompts the addition of W18O49 nanorods
in PVDF nucleates and stabilizes the piezoelectric polar γ-phase
in the nanocomposite. Electrochemical experiments were employed for
the first time to relate the event of the evolution of crystalline
phases in PVDF to the transfer of electrons to the electrolyte from
PVDF using the data from cyclic voltammetry (CV) and electrochemical
impedance spectroscopy (EIS). High dielectric constant (ε′)
and low dielectric loss (ε″) values were obtained proportionately
for different weight percentage additions of W18O49 nanorods in PVDF. DSC was employed to study the crystallization
kinetics of γ-phase evolution. Piezoresponse force microscopy
(PFM) was used to compare the piezoelectric responses from the PVDF
nanocomposites. The W18O49/PVDF nanocomposite
could generate a peak open circuit voltage of ∼6 V and a peak
short circuit current of ∼700 nA. The W18O49/PVDF nanocomposite could light two commercial blue-light-emitting
diodes (LEDs) with hand impulse imparting
Defect-Induced Self-Poling in a W<sub>18</sub>O<sub>49</sub>/PVDF Piezoelectric Energy Harvester
W18O49 nanostructures, previously used for
electrocatalysis, energy storage, electrochromic, and gas sensing
applications, are incorporated in poly(vinylidene fluoride) (PVDF)
in this work for mechanical energy-harvesting applications. X-ray
diffraction spectroscopy (XRD), high-resolution transmission electron
microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), Fourier
transform infrared spectroscopy (FTIR), Raman spectroscopy, differential
scanning calorimetry (DSC), and the polarization-electric (P-E) field
loop test prompts the addition of W18O49 nanorods
in PVDF nucleates and stabilizes the piezoelectric polar γ-phase
in the nanocomposite. Electrochemical experiments were employed for
the first time to relate the event of the evolution of crystalline
phases in PVDF to the transfer of electrons to the electrolyte from
PVDF using the data from cyclic voltammetry (CV) and electrochemical
impedance spectroscopy (EIS). High dielectric constant (ε′)
and low dielectric loss (ε″) values were obtained proportionately
for different weight percentage additions of W18O49 nanorods in PVDF. DSC was employed to study the crystallization
kinetics of γ-phase evolution. Piezoresponse force microscopy
(PFM) was used to compare the piezoelectric responses from the PVDF
nanocomposites. The W18O49/PVDF nanocomposite
could generate a peak open circuit voltage of ∼6 V and a peak
short circuit current of ∼700 nA. The W18O49/PVDF nanocomposite could light two commercial blue-light-emitting
diodes (LEDs) with hand impulse imparting
Search for Origin of Room Temperature Ferromagnetism Properties in Ni-Doped ZnO Nanostructure
The
origin of room temperature (RT) ferromagnetism (FM) in Zn<sub>1–<i>x</i></sub>Ni<sub><i>x</i></sub>O (0< <i>x</i> < 0.125) samples are systematically investigated through physical,
optical, and magnetic properties of nanostructure, prepared by simple
low-temperature wet chemical method. Reitveld refinement of X-ray
diffraction pattern displays an increase in lattice parameters with
strain relaxation and contraction in Zn/O occupancy ratio by means
of Ni-doping. Similarly, scanning electron microscope demonstrates
modification in the morphology from nanorods to nanoflakes with Ni
doping, suggests incorporation of Ni ions in ZnO. More interestingly,
XANES (X-ray absorption near edge spectroscopy) measurements confirm
that Ni is being incorporated in ZnO as Ni<sup>2+</sup>. EXAFS (extended
X-ray absorption fine structure) analysis reveals that structural
disorders near the Zn sites in the ZnO samples upsurges with increasing
Ni concentration. Raman spectroscopy exhibits additional defect driven
vibrational mode (at 275 cm<sup>–1</sup>), appeared only in
Ni-doped samples and the shift with broadening in 580 cm<sup>–1</sup> peak, which manifests the presence of the oxygen vacancy (V<sub>O</sub>) related defects. Moreover, in photoluminescence (PL) spectra,
we have observed a peak at 524 nm, indicating the presence of singly
ionized V<sub>O</sub><sup>+</sup>, which may be activating bound magnetic
polarons (BMPs) in dilute magnetic semiconductors (DMSs). Magnetization
measurements indicate weak ferromagnetism at RT, which rises with
increasing Ni concentration. It is therefore proposed that the effect
of the Ni ions as well as the inherent exchange interactions arising
from V<sub>O</sub><sup>+</sup> assist to produce BMPs, which are accountable
for the RT-FM in Zn<sub>1–<i>x</i></sub>Ni<sub><i>x</i></sub>O (0< <i>x</i> < 0.125) system