Synthesis and Dielectric Relaxation Spectroscopy of Graphene Oxide Nanoparticles: Effects of Frequency, Thickness, and T
- PDF / 1,069,752 Bytes
- 7 Pages / 593.972 x 792 pts Page_size
- 40 Downloads / 187 Views
https://doi.org/10.1007/s11664-020-08355-9 2020 The Minerals, Metals & Materials Society
Synthesis and Dielectric Relaxation Spectroscopy of Graphene Oxide Nanoparticles: Effects of Frequency, Thickness, and Temperature PUSHPENDRA KUMAR,1 SANTHOSH PENTA,1 and SHYAMA PRASAD MAHAPATRA 1,2 1.—Department of Chemistry, National Institute of Technology Raipur, Chhattisgarh 492010, India. 2.—e-mail: [email protected]
Raipur,
Graphene oxide (GO) nanoparticles were synthesized by the modified Hummers method from graphite powder. The synthesized GO nanoparticles were characterized by UV–visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), x-ray diffraction (XRD), and Raman spectroscopy. The SEM and HRTEM analysis showed that the nanoparticles ranged in size from 1 nm to 100 nm. The crystalline properties of the GO sheets were confirmed by XRD analysis. The FTIR results confirmed the presence of oxygen-containing functional groups on the surface of GO nanosheets. The dielectric relaxation spectroscopy of the synthesized GO was studied in the frequency range of 102 Hz to 105 Hz. The dielectric loss tangent as a function of frequency shows a separate relaxation peak and increases up to 6 mm thickness, beyond which it decreases. The dielectric permittivity increases with the thickness of GO pellets up to 6 mm and then decreases, which may be due to an increase in resistivity. The electrical conductivity of GO increases continuously with increasing temperature, confirming the positive temperature coefficient (PTC) of higher conductance. From the dielectric study, it is observed that the dielectric permittivity and electrical conductivity of GO strongly depend upon the thickness and extent of temperature. Key words: Graphene oxide, synthesis, dielectric, conductivity, temperature, percolation
INTRODUCTION Dielectric materials are used to store large amounts of electrical energy, for example, as capacitors and in large-scale power applications.1–3 According to the Lyddane–Sachs–Teller relation, the high permittivity and intrinsic dipole moment is displaced by lattice vibrations.4 Today, the most demanding applications for materials are in energy storage and energy conversion in devices such as batteries, nano-electronics, sensors, and dielectric-
(Received December 24, 2019; accepted July 23, 2020)
based capacitors.5,6 Graphene oxide (GO) is a singleatomic-layered material made by the powerful oxidation of graphite. Graphene has a unique twodimensional framework structure in a repeating pattern of hexagonal carbon atoms, and has garnered huge interest because of its excellent optical, mechanical, thermal, and electronic properties.7–9 Graphene nanosheets were first obtained by the socalled Scotch tape method (mechanical exfoliation) and by epitaxial chemical vapor deposition of bulk graphite.8,10 In 1859, Brodie first synthesized GO by the reaction of potassium chlorate and fuming nitric acid (HNO3).11 S
Data Loading...
