1Department of Physics, SSN College of Engineering, Chennai-603110
Page Number: 1-9
The aim of this study to obtain copper nanoparticles (Cu NPs) through a method of green synthesis that
involves using plant extract of Coldenia Procumbens. Cu NPs were successfully synthesized using the
green synthesis method in the experiments performed. Ultraviolet–visible (UV–Vis) spectrophotometry of
the characteristics of the acquired Cu NPs was performed with scanning electron microscopy (SEM), Xray diffraction (XRD) and Fourier transform infrared spectrometry (FT-IR). It was found that the results
of the SEM and XRD measurements that acquired the Cu NPs were in the size of 50 nm. Absorption peak
at 283 nm and 483 nm were observed by UV of Cu NPs. Afterwards, the antibacterial activities of these nanoparticles were measured, and it was understood from the obtained results that Cu NPs have both antibacterial and antimicrobial activities.
Keywords: CuNPs; Green synthesis; Nano particles; Coldenia Procumbens;
Anju Rani1 , R. L. Dhiman2, Virender Singh3
, Suresh Kumar3 and Suresh Kumar1,4
1Department of Physics, M.M. University, Sadopur, Ambala - 134 007 India
2Department of Physics, Sanatan Dharma College, Ambala Cantt.- 133 001 India
3 Department of Electronic Science, Kurukshetra University, Kurukshetra - 136 119, India
4Department of Physics, M.M. (Deemed to be University), Mullana-Ambala-133 207 India
Page Number: 10-20
Cobalt, Iron & Cerium co-doped CoxFe0.02Ce0.02Ti0.96-xO2; x = 0.02, 0.03 & 0.04 mol % nanoparticles were
fabricated by following sol-gel process. Characterization of synthesized samples was carried out through
X-ray diffraction, UV-visible and Fourier transform infrared spectroscopy, Transmission electron and
Field-emission scanning electron microscopy and Electron dispersive X-ray spectroscopy. Anatase phase
of fabricated nanoparticles was estimated by XRD and further verified by EDXS measurements. Using
Debye Scherrer’s formula the particle size of synthesized nanoparticles calculated was 24.8 to 10.3 nm.
With growing cobalt concentration (x) shifting of absorption edge towards region of higher wave length
correspond to blue shift as noticed from UV–Visible absorption spectra indicate the generation of energy
sub states within forbidden gap and reduction in energy band gap from 2.57 eV to 1.69 eV. Structural
formation of the synthesized nanoparticles was studied by FTIR spectroscopy which confirm that formed
TiO2 nanoparticles have stable anatase pahse. Photocatalytic degradation activity against congo red and
methyl orange dyes was detected by visible light illumination. Observations showed that with rise in
cobalt concentration (x) the photocatalytic activity rises which is ascribed to decreasing rate of
carrier
recombination and increasing surface area of the fabricated nanoparticles.
Rezwana Sultana1,2,*, Karimul Islam1,2 and Supratic
Chakraborty1
1Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064, India
2Homi Bhabha National Institute, BARC Training School Complex, Anushaktinagar, Mumbai 400
094, India
Page Number: 21-27
In this work, ZrxHf1–xO2 thin films were deposited on silicon substrate (n-type) using co-sputtering
technique at various O2/Ar ratios in the plasma. X-ray photoelectron spectroscopy (XPS) and scanning
electron microscopy (SEM) technique have been employed to study the chemical composition and surface
morphology of ZrxHf1–xO2 thin films, respectively. Capacitance-voltage (C-V) and current-voltage (I-V)
measurements have been performed to look on the electrical response of all the deposited thin films.
Exploration of XPS data reveals that the number of defect states present in the film decreases with
increasing oxygen flow rate. The SEM images confirm that surface roughness of the as deposited films
enhance with the increasing grain size. From the C-V curve measured at 1 MHz frequency, oxide charge
density (Qox) and interface charge density (Dit) have been calculated. The film deposited at O2/Ar gas
flow
ratio of 1:3 gives higher value of QOX for smaller grain size. Structural reduction and lesser
unsaturated
bonds at the ZrxHf1–xO2/Si interface cause the minimum Dit at a ratio of 1:5. Current-voltage (I-V)
measurement indicates clearly that the leakage current decrease with increasing argon flow rate.
Electrical
properties and surface morphology of all the films were studied and a correlation has been made between
the surface morphology and electrical properties of all the films.
Keywords: RF reactive co-sputtering, X-ray photoelectron spectroscopy, Scanning
electron microscopy,
MOS device, thin film.
Karimul Islam 1,2 *, Rezwana Sultana1,2 , and Supratic
Chakraborty1
1Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064, India
2Homi Bhabha National Institute, BARC Training School Complex, Anushaktinagar, Mumbai 400
094,
India
Page Number: 28-34
Niobium oxynitride (NbON) thin films were deposited on silicon substrate using DC reactive magnetron
sputtering technique of niobium metal targets at different nitrous oxide (N2O) and oxygen flow in the
plasma during deposition. To get NbON thin films, the deposition parameters were also optimized. X-ray
reflectivity (XRR) technique was used to estimate the film thickness of the as deposited films. The
films'
surface morphology and chemical compositions were investigated by field-emission scanning electron
microscopy (FE-SEM) and x-ray photoelectron spectroscopy (XPS) techniques. SEM images indicate the
smooth surface morphology of the deposited films. XPS study exposes the noticeable presence of N2 in
the niobium oxynitride films deposited with only 20 sccm nitrous oxide flows in the plasma. The leakage
current-voltage (I-V) measurement reveals the reduction in leakage current with higher N2O and lowers
oxygen flow rates. The resistivity of the thin films was measured. The thin films deposited with higher
N2O flow give high resistivity because of lesser availability of defect states. It may be stated that
nitrous
oxide content reduces the leakage current thus, improves the film and interface properties.
1Department of Physics & Astronomy, National Institute of Technology, Rourkela, 769008, India
.
Page Number: 35-40
Carbon nanoparticles (CNPs) have emerged as a promising candidate because of their interesting
properties.
They can be synthesized by chemical method as well as through green chemistry. Herein, we report a green
synthesis approach for the CNPs from spider silk by pyrolysis at temperature 400 ℃ without using any
carbonizing or passivating agent. The structural and optical properties of the synthesized CNPs have
been
characterized by using X-Ray diffraction (XRD), Raman spectroscopy, SEM (scanning electron
microscope) - Energy Dispersive X-Ray (EDAX) analysis, UV–Visible and photoluminescence (PL)
spectroscopy. The results obtained show that prepared carbon nanoparticles (CNPs) have a great potential
for bio-sensing, bio-imaging, disease diagnosis, and other different optoelectronic device applications.
1
Department of Physics, Barasat Government College, Kolkata-700124, W.B., India.
2
Department of Physics, West Bengal State University, Kolkata-700126, W.B., India.
Page Number: 41-52
The hollandite K2Cr8O16 undergoes a transition from the paramagnetic metal to ferromagnetic metal (FM)
at Tc = 180 K and finally metal-insulator transition (MIT) occurs at the transition temperature TMI = 95 K,
preserving ferromagnetism in the low temperature insulating phase. Although ferromagnetism in the
insulating phase of K2Cr8O16 at low-temperature has been explained using Peierls instability mechanism,
the role played by cation Potassium in determining this unique ground state of K2Cr8O16 is yet to be
explored. In the present study, the effect of a single and full K+ de-insertion on the electronic and
magnetic properties of K2Cr8O16 for the high-temperature structure is investigated using Density
Functional theory. It is imperative that extraction of K+
-ions destroys the K-Cr interaction through the
oxygen anions for K1Cr8O16/CrO2. This enhances the Cr(d)-O(p) hybridization. The pseudo-gap at Fermi
energy in K2Cr8O16 shifts to higher energy due to K+ de-insertion. Furthermore, removal of K-ions from
the tunnel sites increases the density of states at Fermi level, which is mainly derived from Cr-3d
conduction electrons. As the Fermi energy moves more towards the edge of the Cr-d band and away from
pseudo gap, Tc increases as it should within the Stoner mechanism governing band ferromagnetism. The
strength of ferromagnetism enhances due to increase in the Cr-Cr coupling for isostructural K1Cr8O16 and
CrO2 as Cr-d and O-p coupling increases with K+
removal.
