National Institute of Technology Calicut

About: National Institute of Technology Calicut is a education organization based out in Kozhikode, Kerala, India. It is known for research contribution in the topics: Computer science & Control theory. The organization has 3627 authors who have published 4638 publications receiving 50830 citations. The organization is also known as: Calicut Regional Engineering College & NIT Calicut.

Preparation and characterization of poly(vinylidene fluoride‐trifluoroethylene)/barium titanate polymer nanocomposite for ferroelectric applications

Abstract: Barium titanate nanoparticles with an average size of <100 nm were added to poly(vinylidene fluoride-trifluoroethylene) copolymer in varying concentrations (0.2, 0.4, 0.6, and 0.8 wt%) in liquid phase under bath sonication and annealed at 120°C for 2 h. The Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, and Differential scanning calorimetry studies reveals an increase in the β-phase content of the nanocomposite, which is a promising inference for the increased ferroelectric property of the material. Scanning electron microscopy and Atomic force microscopy was used to study the surface topography of the spin coated thin films. Polarization–electric field studies clearly indicating the enhanced ferroelectric nature of optimized concentration with highest remnant polarization. All these results nominate this polymer nanocomposite as a promising material for ferroelectric applications like nonvolatile memory devices. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers

XPS study of the band alignment at ITO/oxide (n-type MoO3 or p-type NiO) interface

Abstract: While they have different electronic properties n-type MoO3 and p-type NiO are very efficient as buffer layers between the ITO anode and the organic electron donor in organic photovoltaic cells. While it is admitted that MoO3 is n-type, its band structure is still under study. Here, the band alignment at the interface of an ITO/MoO3 heterojunction is studied by X-ray photoelectron spectroscopy (XPS). The same study is realized on the structure ITO/NiO, NiO being a p-type semiconductor. The measurements have been performed on samples obtained under the same experimental conditions as those used to achieve organic photovoltaic cells. The MoO3 (NiO) upper layer was 3 nm thick. The semidirect XPS technique used to measure the band offsets allows us to estimate the band discontinuities at the interface ITO/MoO3: ΔEv = 0.50 eV and ΔEc = 0.90 eV, while at the interface ITO/NiO we have ΔEv = −2.10 eV and ΔEc = −1.90 eV. Therefore, n-type MoO3 and p-type NiO, which are both very efficient anode buffer layers (ABLs), exhibit different band structure at the contact with ITO. However, the measurement, by means of a Kelvin probe, of the work functions of the structures ITO/NiO and ITO/MoO3, shows that they are close and significantly higher than that of ITO alone.

Development of epoxy-aluminum nanocomposite dielectric material with low filler concentration for embedded capacitor applications

Abstract: This paper presents the development of epoxy-aluminum nanocomposites as a dielectric material by adopting a relatively low concentration of filler to obtain high dielectric constant simultaneously retaining low dielectric loss. Epoxy-aluminum nanocomposite is modeled as a three phase material and dielectric constant of the composite is evaluated using this model. Experimental analysis is done and dielectric properties of the composite is characterized as a function of filler loading and frequency. It is observed that the theoretical and experimental analysis match well at lower filler concentrations. Dielectric property measurement demonstrated that, for composite containing 18 wt% 70 nm aluminum, a dielectric constant of 25 and a low dissipation factor of 0.06 can be achieved. The dielectric constant of epoxy-aluminum composite is increased by factor 7 at this lower filler loading as compared with that of pure epoxy matrix. The increase in dielectric constant with addition of aluminum is attributed to interfacial polarization. An attempt is made to understand the effect of inter particle distance on the dielectric properties of the nanocomposite. It is seen that the dielectric constant attained maximum value at 18 wt% filler loading, for which the inter particle distance reaches a value almost equal to the filler diameter (70 nm) itself.