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Indian Journal of Pure & Applied Physics (IJPAP)

Title: Novel methods to reduce leakage current in Si PIN photodiodes designed and fabricated with different dielectrics

Authors: Rao, Y P Prabhakara; Praveen, K C; Rani, Y Rejeena; Prakash, A P Gnana

Abstract: The silicon PIN
photodiodes were designed and fabricated in the conventional bipolar planar
technology by using novel methods to reduce the leakage current. The new process
steps like gettering, oxide stacking fault removing, ion implantation with
suitable masking and improving shallow junction technology were implemented to
fabricate PIN photodiodes of different active area such as 1 mm 1 mm, 2 mm 2 mm and
10 mm 10 mm. The performance of PIN
photodiodes has been studied by measuring dark current, C-V
characteristics and spectral response. The two different dielectrics such as
silicon dioxide (SiO2) and silicon nitride (Si3N4) with different thickness were used as
anti-reflective coating (ARC). The electrical characteristics and spectral
measurements exhibit that the photodiodes are highly sensitive with low leakage

Page(s): 637-644 2014/09/19 - 19:05

Title: Dielectric relaxation studies of polyvinylpyrrolidone (PVP) and polyvinylbutyral (PVB) in benzene solutions at microwave frequency

Authors: Rawat, A; Mahavar, H K; Tanwar, A; Singh, P J

Abstract: Microwave dielectric
relaxation measurements on polyvinylpyrrolidone (PVP), polyvinylbutyral (PVB)
and their binary mixture have been done in dilute solutions of benzene at 9.015
GHz at 303K temperature. The heterogeneous molecular interactions and
intra-molecular rotations of these polymers in dilute solutions have been studied
by comparing the evaluated values of average relaxation time (τ0),
relaxation times corresponding to overall molecular rotation (τ1)
and intra-molecular rotation (τ2). The values of different
dielectric parameters namely; static permittivity (є0), dielectric
constant (є'), dielectric loss (є") and optical permittivity (є∞) have been determined for
five different mole fractions of PVP-PVB. The dipole moment (μ) and free energy
of activation ∆Fє were also calculated. It is observed that
the value of μ decreases, whereas ∆Fє increases with the
increase of mole fraction of PVP in the mixture. The higher values of the
distribution parameter (α) indicate that besides the overall rotation,
there is a large contribution of segmental reorientation and group rotation to
the relaxation processes.

Page(s): 632-636 2014/09/19 - 19:05

Title: Dielectric properties of spinel Co3-xMnxO4 (x = 0.1, 0.4, 0.7, and 1.0) ceramic compositions

Authors: Meena, P L; Sreenivas, K; Kumar, Ravi

Abstract: Cobalt manganese
oxides Co3-xMnxO4 (x = 0.1, 0.4, 0.7, and 1.0) multi-ferroic ceramic were prepared by conventional solid state technique to
understand the effect of Mn substitution at Co site on the structural and
dielectric properties. Single phase polycrystalline with a linear increase in
the lattice parameter ‘a’ was
observed without any structural change in cubic crystal symmetry with Mn
substitution. The effect of Mn substitution on the dielectric constant (ε') and loss tangent (tan) was
measured over a wide temperature range (150-450 K) and frequency range (100-900
kHz). A very weak frequency dispersion and small temperature dependence was
observed in ε' and tan at low temperature, however, ε' and tan display
a strong frequency and temperature dependency at higher temperature. The ε' shows a ferroelectric like transition
and shift to lower temperature with Mn incorporation. The behaviour of tan shows dielectric
relaxation and also shifts towards lower temperature with Mn incorporation. The
ceramic compositions show universal dielectric response with temperature
dependent exponent
factor‘s’ and which fall in Jonscher’s range.

Page(s): 625-631 2014/09/19 - 19:05

Title: Solar cells of Cu2ZnSnS4 thin films prepared by chemical bath deposition method

Authors: Subramaniam, E P; Rajesh, G; Muthukumarasamy, N; Thambidurai, M; Asokan, Vijayshankar; Velauthapillai, Dhayalan

Abstract: Solar cells based on
kesterite-type Cu2ZnSnS4 have been successfully
fabricated on ITO substrates by cost effective chemical bath deposition method.
The structural properties of the material have been studied using X-ray
diffraction pattern and it confirms the formation of Cu2ZnSnS4
with kesterite structure. The surface topography has been studied using atomic
force microscope and the rms roughness of the film was found to be 3.2 nm. The
chemical constituents present in the prepared films have been identified using
energy dispersive X-ray analysis. The optical band gap energy of CZTS thin film
was found to be 1.5 eV which is quite close to the optimum value required for
solar cell application. The power conversion efficiency of fabricated Cu2ZnSnS4
based solar cell is 1.34%.

Page(s): 620-624 2014/09/19 - 19:05

Title: Estimation of volume dependence of Grüneisen parameter for NaCl and -Fe

Authors: Kumar, Sanjay; Sharma, S K; Pandey, O P

Abstract: The present paper
proposes a new empirical expression to evaluate the values of volume dependence
of the Grüneisen parameter. NaCl and -Fe have been taken to check the reliability of the
present expression. The results obtained reveal that the present model is reliable
due to a reasonably good agreement between calculated values and the values of Grüneisen
parameter derived from experimental data on thermoelastic properties.

Page(s): 541-544 2014/08/05 - 22:53

Title: Assisted cloning of an arbitrary unknown two-qubit state via a genuine four-qubit entangled state and positive operator-valued measure

Authors: Lian-Fang, Han; Hao, Yuan; Ming, Yang; Zhuo-Liang, Cao

Abstract: A protocol for
cloning an arbitrary unknown two-qubit state and its orthogonal complement
state with the assistance of a state preparer is presented. In this paper, a
genuine four-particle entangled state which cannot be reduced to the product of
two Bell states is used as the quantum channel. Moreover, positive
operator-valued measure (POVM) instead of usual projective measurement is
employed. In one hand, the usual teleportation is required. And in another
hand, the perfect copies and complement copies of an unknown two-particle state
can be implemented with a certain probability in the help of the state

Page(s): 563-570 2014/08/05 - 22:53

Title: Three-input-one-output current-mode universal biquadratic filter using one differential difference current conveyor

Authors: Horng, Jiun-Wei; Wu, Chang-Ming; Herencsar, Norbert

Abstract: A current-mode
universal biquadratic filter is presented. The architecture has three input
terminals, one output terminal using one differential difference current
conveyor (DDCC), two grounded capacitors and two resistors. It can realize all
standard second-order filter functions, which are, highpass, bandpass, lowpass,
notch and allpass responses without changing the circuit topology. The proposed
circuit employs only one DDCC that simplifies the circuit configuration.

Page(s): 556-562 2014/08/05 - 22:53

Title: Hydrothermal synthesis of NiFe2O4, Ni0.6Zn0.4Fe2O4 and Ni0.6Zn0.4Fe2O4/SrFe2O4: nanostructure, magnetic and dielectric properties

Authors: Singh, Sukhdeep; Singh, Manpreet; Kotnala, R K; Verma, Kuldeep Chand

Abstract: NiFe2O4
(NF), Ni0.6Zn0.4Fe2O4 (NZF) and
(NZF/SF) nanostructures were prepared by hydrothermal synthesis at 180°C/48 h. The synthesis of NF shows nanoparticles of average size 19
nm. However, NZF and NZF/SF show nanowires of average diameter ~23 and 6 nm,
and length 325 and 160 nm, respectively. A growth mechanism for fabrication of
nanostructure is given. The X-ray diffraction pattern confirms the
polycrystalline structure of spinel phase of NF and NZF and orthorhombic phase
of SF ferrite. The microstructural analysis is confirmed by transmission
electron microscopy. The ferromagnetic behaviour of each ferrite sample is
confirmed by M-H hysteresis. However, the M-H hysteresis of composite NZF/SF also
shows spring like vibrations which indicate a strong coupling between hard and
soft phases. The higher value of remanent magnetization is observed in NZF/SF
which is possible by combining soft/hard ferrite phase. The effect of low
dimensions of NZF/SF nanostructure is to control dielectric constant with low
loss up to higher frequency of 120 MHz, has been observed.

Page(s): 550-555 2014/08/05 - 22:53

Title: RF plasma polymerization and electrical, optical and structural properties of thin films of poly(o-toluidine)

Authors: Islam, Shama; Lakshmi, G B V S; Zulfequar, M; Husain, M; Siddiqui, Azher M

Abstract: Thin films of poly(o-toluidine)
(POT) have been prepared by RF plasma polymerization at radio frequency
(RF) power input 15 W, making suitable modifications in a RF-sputtering
set-up. The deposition rate is found to be 3.33 nm/min. The films are
characterized by dc conductivity, UV-Visible, FTIR and XRD techniques. The dc conductivity of the POT thin
films has been analyzed in the temperature range 312-435 K and is found to
increase with temperature. The Arrhenious plot of dc conductivity
shows straight line behaviour. The optical band gap has been estimated to be
1.66 eV from UV-visible absorption spectrum. From FTIR, the formation of POT
has been confirmed. It is found that the synthesized polymer is cross-linked.
Thickness of the polymer films has been measured to be 200 nm by ellipsometry.
XRD shows the amorphous nature of the prepared films.

Page(s): 486-490 2014/07/04 - 23:51

Title: Facile synthesis of phenolic resin sheets consisting expanded graphite/-Fe2O3/SiO2 composite and its enhanced electromagnetic interference shielding properties

Authors: Mishra, Monika; Singh, Avanish Pratap; Sambyal, Pradeep; Teotia, Satish; Dhawan, Sundeep Kumar

Abstract: The paper reports the preparation of thin sheets of expanded graphite
decorated with -Fe2O3 and SiO2 by
compression molding. Different formulations have been prepared to study the
effect of dielectric and magnetic constituent on the electrical, magnetic and
dielectric properties of multiphase composite. One of the formulations shows
unprecedented microwave shielding response with absorption dominated shielding
effectiveness value of 55.40
dB which strongly depends on dielectric losses and magnetic losses. The results
show that the dielectric loss of the composites can be attributed to natural
resonance, electron polarization relaxation, interfacial polarization and the
unique layered nanostructures etc.; whereas eddy current effect mainly causes
the magnetic loss. Since observed attenuation is greater than the recommended
limit (30 to 40 dB) of commercial application, therefore, these are potentially
applied for absorbing mobile signal interference in daily life.

Page(s): 478-485 2014/07/04 - 23:51

Title: Effect of quantum correction on thermal instability of self-gravitating two component plasma

Authors: Shrivastava, V; Patidar, A K; Pensia, R K

Abstract: The effect of
quantum correction on thermal
instability of magnetized, viscous self-gravitating two component plasma
has been studied by means of linear perturbation analysis. The dispersion
relation for longitudinal and transverse mode of propagation has been described
and discussed it for some limiting cases. The condition of instability as well
as stability of the system has been discussed by applying Routh-Hurwitz
criterion. It is found that due to the self-gravitation of the medium, the
condition of thermal instability changes into the condition of radiative
instability. Quantum parameter affects the condition of radiative instability
in both longitudinal and transverse direction of propagation, while the
magnetic field affects only in transverse direction. It is concluded that the
effect of viscosity, temperature dependent heat-loss function; quantum parameter
and magnetic field have a stabilizing influence, while the thermal conductivity
and density dependent heat-loss function have destabilizing influence on the
Jeans instability.

Page(s): 465-477 2014/07/04 - 23:51

Title: Numerical complexity of real-time tracking of objects in defined space by infrared optoelectronic devices

Authors: Knežević, Dragan; Dragović, Magdalena; Ibrahimović, Vedran; Srećković, Milesa; Kovačević, Aleksander G

Abstract: Remote tracking and
recognition of various objects in defined space are complex multidisciplinary
problems. Depending on selected scene being investigated (object size and
dynamics, time needed for data processing and estimation), and on chosen
optoelectronic system design, several solutions are available. For the
fieldwork, the passive remote detection seems to be the most convenient.
Economically reasonable approach with selected non-sophisticated modest equipment
is proposed, evaluated and discussed. A numerical experiment is performed with
own-developed algorithm in which unreal cases are automatically eliminated
during the output vector data evaluation. Gaussian distribution method is
implemented here. The average calculated times, resulted from simulation, were
shorter than simulated values increased by 3 σ.

Page(s): 457-464 2014/07/04 - 23:51

Title: Two band model for the iron based superconductors

Authors: Nuwal, Anuj; Kakani, Shubhra; Kakani, S L

Abstract: Two band model for
Fe-As based oxygen containing superconductors is developed using the Green’s
function technique and equation of motion method. Self-consistent equations for
superconducting order parameters (p,d, specific heat (Ces) and density of states
are derived. The theory is applied to explain the experimental results in
oxygen containing Fe-As superconductors Sm0.95La0.05O0.85F0.85Fe0.15FeAs
and SmO1-xFxFeAs. The comparison to experimental data is given
where these are available. The agreement between theory and experiments is
quite encouraging.

Page(s): 411-422 2014/06/14 - 17:47

Title: Dielectric properties of wet and fertilized soils at radio frequencies

Authors: Gadani, D H; Vyas, A D; Rana, V A

Abstract: he dielectric
constant ' and dielectric loss " of moist soil and
fertilized soil have been
measured in the frequency
range 10 kHz-2 MHz using a precision
LCR meter. The values of ' and " of the wet (Gandhinagar district sandy
loam) soil are found to decrease with increase in frequency from 10 kHz to 2 MHz. The value
of tan d is found to increase with increase in moisture content in the soil.
The peak of tand is found to shift
lower frequency
side as the moisture content in the soil increases. The conductivity spectra
of soil show the increase in
conductivity * = ' + j" with increase in moisture content in the soil. The value of increases
slowly with increase in frequency for wet soil. A dip is observed in the value
of " spectra at electrode polarization
frequency, which is also
observed in complex impedance
plane plot
of the wet soils. To see the effect of fertilizer on the soil
two fertilizers are selected, sulphet of potash (SOP) and zinc chelate. It has
been observed that ' and " of the wet fertilized soils decrease with increase in frequency
from 10 kHz to 2 MHz. Further, the values of ' and " increase with increase in % concentration
of fertilizer in the wet soil. The variation of tan and conductivity with
frequency and fertilizer in the soils has also been studied.

Page(s): 399-410 2014/06/14 - 17:47

Title: Voltage differencing transconductance amplifier-based floating simulators with a single grounded capacitor

Authors: Tangsrirat, Worapong; Unhavanich, Sumalee

Abstract: Two simple configurations for simulating the resistorless floating inductor
and capacitor using voltage differencing transconductance amplifier (VDTA) as a
novel active element have been presented in this paper. The proposed floating
simulated inductance circuit uses only one VDTA and one grounded capacitor,
whereas the proposed floating simulated capacitance circuit uses two VDTAs and
one grounded capacitor. The equivalent values of the realized simulators can be
tuned electronically through the transconductance parameter of the VDTA. Both
of the circuits also do not require any realization conditions. The proposed
circuits together with their applications are demonstrated using PSPICE
simulation with 0.35 m TSMC CMOS technology.

Page(s): 423-428 2014/06/14 - 17:47

Title: Polarizability investigation by first order phase transition in the self-consistent phonon approximation for PSN system

Authors: Uniyal, Manish; Bhatt, S C

Abstract: Considering a
quadratic Anharmonic model Hamiltonian and using double time temperature
dependent Green's function method and Dyson's equation treatment, expression
for polarizablity in the frequency response for mixed perovskite type
ferroelectrics has been obtained. Using the experimentally observed temperature
dependent dielectric constant, loss tangent, soft mode frequency and width for
Na1-x KxNbO3 (where x = 0, 0.4 and 0.5), the
polarizablity has been calculated for these samples at 10 and 100 kHz.

Page(s): 391-394 2014/06/14 - 17:47

Title: Effect of molar concentration on structural, morphological and optical properties of CdS thin films obtained by SILAR method

Authors: Manikandan, K; Mani, P; Inbaraj, P Fermi Hilbert; Joseph, T Dominic; Thangaraj, V; Dilip, C Surendra; Prince, J Joseph

Abstract: Thin films of cadmium sulphide (CdS) were deposited on a glass
plate by the SILAR method for 0.05, 0.10 and 0.15 M
concentrations. The structural, optical and morphological properties of the
films were characterized by X-ray diffraction (XRD), energy dispersive spectrum
(EDS), UV-Vis spectrometry and atomic force microscopy (AFM) techniques. The XRD patterns of the films
indicated that the crystalline natured films have hexagonal phases.
The energy-dispersive spectrum (EDS) analysis confirms the compositions of
cadmium and sulphur in CdS films. The direct band gap
values in the range 2.32-2.24 eV were observed from the transmittance studies,
the results infer that the band gap energy decreases with increasing molar
concentration. The AFM studies show that the film is evenly coated and has
uniform grain sizes.

Page(s): 354-359 2014/05/13 - 17:21

Title: Optical and electronic properties of iron xanthate thin film

Authors: Kariper, İ A; Özpozan, T

Abstract: The iron xanthate
thin films (IXTF) were deposited by the chemical bath deposition method on
various substrates, such as amorphous glass, p and n-silicon, indium
tin oxide and poly(methyl methacrylate). The
structure of the films was analyzed by far-infrared spectrum (FIR),
mid-infrared (MIR) spectrum and scanning electron microscope (SEM) and their
structural, optical and electrical properties were examined. Electrical
properties were measured using the four-point method whereas optical properties
were investigated via the UV-VIS spectroscopic technique. The transmittance was
found to be 70-80% at optimum deposition time and temperature (4 h, 50°C). The optical band gap of the IXTF was graphically estimated to be
3.62-3.83 eV. The resistivity of the films was calculated to be between
23.5-38.5 Ω∙cm on commercial glass depending on the film thickness and between
23.8-42.0 Ω∙cm on the other substrates. It was found that resistivity changed
with film thickness. The MIR and FIR spectra of the films were in line with the
literature analogues.

Page(s): 348-353 2014/05/13 - 17:21

Title: Synthesis and characterization of polyaniline/TiO2 composites

Authors: Asha; Goyal, Sneh Lata; Kumar, D; Kumar, Shyam; Kishore, N

Abstract: The synthesis and
characterization of polyaniline (PANI)/TiO2 polymer composites have
been studied. The synthesis method is based on chemical oxidative
polymerization of aniline added with various weight % of TiO2 in the
presence of ammonium persulphate as an oxidant. The results of XRD confirm the
presence of TiO2 in the composites. The FTIR shows systematic
shifting of the characteristic bands of PANI with the increase in content of TiO2.
The SEM images revealed uniform distribution of TiO2 particles
in the PANI matrix. The evaluation of the dynamical parameters for PANI/TiO2
composites using technique such as TGA has been reported. The thermal
stability of composites increases with the increase in TiO2 weight
%. Although PANI/TiO2 composites show lower dc electrical
conductivity as compared
to PANI and the conductivity decreases with increasing content of TiO2,
but they show a higher thermal stability than that of PANI. Further, the
dc electrical conductivity is observed to increase with the increase in
temperature. This work opens new perspectives for the use of PANI/TiO2 composites
as a conducting material at high temperatures.

Page(s): 341-347 2014/05/13 - 17:21

Title: Isothermal and adiabatic extrapolations of thermoelastic properties to extreme compression

Authors: Shanker, J; Singh, P K; Singh, M P

Abstract: The extreme
compression limits of thermal expansivity, isothermal bulk modulus, adiabatic
bulk modulus and products of thermal expansivity and bulk modulus have been
obtained using the basic principles of calculus and some thermodynamic
identities in terms of the Anderson-Grüneisen parameters and pressure
derivatives of bulk modulus. The isothermal extrapolations are found to be
different from the corresponding adiabatic extrapolations. The results have
been obtained using the Stacey thermodynamics of materials at infinite

Page(s): 337-340 2014/05/13 - 17:21

Title: CCCIIs-based sinusoidal quadrature oscillators with non-interactive control of condition and frequency

Authors: Summart, Saksit; Thongsopa, Chanchai; Jaikla, Winai

Abstract: The paper presents two current-mode quadrature oscillators with
non-interactive two current controls for both of the condition of oscillation
(CO) and the frequency of oscillation (FO) using current controlled current
conveyors (CCCIIs). The proposed oscillators can provide two sinusoidal output
currents with 90 degrees phase difference. It also provides high output
impedances that make the circuit can directly drive load without additional
current buffer. The condition of oscillation and frequency of oscillation can
be controlled by adjusting the bias currents of the CCCIIs. The proposed
circuits use only grounded capacitors without any external resistor which is
very appropriate for further development into an
integrated circuit. The
results of PSPICE simulation program are corresponding to the theoretical

Page(s): 277-283 2014/04/06 - 04:02

Title: Screening mechanism and multi-vortices in dual QCD vacuum

Authors: Nandan, H; Bezares-Roder, N M; Chandola, H C

Abstract: The screening effects in a chromodynamic vacuum which act as dual superconductor in
the background of the magnetic condensation, have been studied. The colour
charge and colour electric flux screening mechanism have been investigated and
these screening effects are shown to be responsible for the colour confinement in dual
QCD. It is also demonstrated that with the transition from the type-II to
type-I in dual QCD vacuum at strong coupling constant as 0.5, there exist n-vortex solutions with
Bogomol’nyi-Prasad-Sommerfeld (BPS) conditions.

Page(s): 271-276 2014/04/06 - 04:02

Title: Electronic microscopic, thermal and electrical properties of Bi2V1-xTixO5.5-δ (0.05≤x≤0.20) oxide ion conductors

Authors: Kaur, Gurbinder; Pandey, O P; Singh, K

Abstract: In the present study,
the effect of titanium substitution for vanadium on oxide ion conductivity,
phase stability and thermal expansion has been investigated. The exact solid
solubility limit of the dopant and its effect on conductivity as well as
thermal expansion, have been studied. The samples have been prepared by
conventional solid-state technique. The sintered samples were characterized
using differential thermal analysis (DTA), thermo-gravimetric analysis (TGA),
X-ray diffraction (XRD) and scanning electron microscopy (SEM). Sample x = 0.20 has shown maximum conductivity
of 1.210-3 S/cm with minimum activation energy
of 0.19 eV at 800°C. Along with this, maximum thermal
expansion coefficient (TEC) is observed for x = 0.2 sample. The microstructures of
the samples exhibited variation in grain size and porosity.

Page(s): 262-270 2014/04/06 - 04:02

Title: Effect of doping cations Li(I)-, Ca(II)-, Ce(IV)- and V(V)- on the properties and crystalline perfection of potassium dihydrogen phosphate crystals: A comparative study

Authors: Ramasamy, G; Bhagavannarayanana, G; Meenakshisundaram, Subbiah

Abstract: The effect of doping metal ions with varied ionic
charges (ranging from +1 to +5), Li(I)-, Ca(II)-, Ce(IV)- and V(V)- on the
growth process and properties of potassium dihydrogen phosphate (KDP) crystals,
grown by slow evaporation solution growth technique, has been investigated.
Incorporation of metal ion into the KDP crystalline matrix is well confirmed by
energy dispersive X-ray spectroscopy and atomic absorption spectroscopy.
Interesting to observe that the incorporation is comparatively less in doping the
higher valent metal. The powder XRD pattern and Fourier transform-IR analysis
confirm the slight distortion in the structure of the KDP crystals as a result
of metal ion doping. Slight changes in cell parameter values of doped KDP
crystals are observed by single crystal XRD analysis. The high-resolution X-ray
diffraction (HRXRD) studies used to evaluate the crystalline perfection reveal
many interesting features on the ability of accommodating the dopants by the
crystalline matrix. Surface morphological changes because of foreign metal ion
incorporation are observed by scanning electron microscopy. UV-Vis spectroscopy
reveals that the transparency is not affected much by the dopants and the
cut-off wavelengths of all the doped specimens lie in a close range. Band-gap
energies are estimated using optical transmittance data. Enhanced second
harmonic generation efficiency is observed.

Page(s): 255-261 2014/04/06 - 04:02

Title: Role of Schottky-ohmic separation length on dc properties of Schottky diode

Authors: Chattopadhyay, P; Banerjee, A

Abstract: The effect of
Schottky-ohmic separation length on the barrier height, ideality factor and
device series resistance of Al-p-Si Schottky barrier diodes in planar
configuration have been studied. It has been found that the ideality factor and
series resistance of the device vary nonlinearly with Schottky-ohmic separation
length. The effect seems to be more pronounced on the series resistance, which
has been attributed to recombination processes at the defect states and non-ohmicity
at the ohmic contact of the device. The fitting of the experimental data
confirms our previous observations of a logarithmic voltage dependence of the
series resistance of the device.

Page(s): 198-202 2014/03/04 - 15:45

Title: Structural, morphological and optical properties of silver doped polyvinylpyrrolidone composites

Authors: Khan, Sharief ud Din; Ahmed, Bashir; Raghuvanshi, S K; Wahab, M A

Abstract: Polyvinylpyrrolidone
(PVP) doped with different silver
concentration (Ag: PVP) composites were prepared by simple solution casting
technique using PVP and silver nitrate. The structural, morphological and
optical properties of these as grown composites were characterized by powdered
X-ray diffraction, SEM, FTIR and UV-VIS techniques. XRD patterns confirm the
incorporation of Ag particles in PVP matrix and indicate the improvement in
polycrystalline behaviour by the appearance of more diffraction peaks with
increased intensity on increasing AgNO3 concentration in the
composites. SEM images reveal the uniform dispersion and increased
densification of Ag particles in PVP matrix. Infrared transmission spectra
recorded in 4000-400 cm-1 region show the characteristic peaks of PVP bonding groups with the
minor shift in their position due to Ag doping. UV-VIS spectroscopy results
reflected that absorption increases in asymmetric manner and the absorption
peak showed red shift with increasing dopant concentration. These results
showed that the simple synthesis process can be used for the preparation of
such composites suitable for various practical applications.

Page(s): 192-197 2014/03/04 - 15:45

Title: Effect of controlled doping on electrical properties and permittivity of PTSA doped polyanilines and their EMI shielding performance

Authors: Saini, Parveen; Arora, Manju; Arya, S K; Tawale, Jai S

Abstract: Emeraldine base (EB) has been protonated with different
concentration of para-toluene sulfonic acid (PTSA) to form doped polyanilines (PANIs). These samples have been characterized by various techniques and
a detailed correlation between dopant concentration and structural, thermal,
electrical and electromagnetic properties has been established. The FTIR/UV-Visible and EPR spectra confirm the formation of
polarons as proto-generated charge carriers whose concentration follows the
dopant concentration trend. It was also observed that increase in doping level
leads to systematic improvement of electrical conductivity (1.21-9 to 5.3
S/cm) as well as complex permittivity (ε'~5.5 & ε"~0.6 to ε'~22.3 & ε"~24.6)
with parallel improvement of electromagnetic (EM) radiation blocking capacity
from -3.8
dB (for EB) to -23.9 dB (for 1.0 M PTSA doped
sample). Further, the attenuation was found to be
critically dependent on dopant concentration, complex permittivity and
electrical conductivity revealing that both polarization as well as conduction is important for
achieving high attenuation. It was also observed that reflection is main
phenomenon at low doping level whereas absorption becomes increasingly
important at higher doping levels and extends dominant contribution towards
total attenuation.

Page(s): 175-182 2014/03/04 - 15:45

Title: Coaxial microcalorimeter – National standard for microwave power up to 18 GHz at NPLI

Authors: Ahmad, Saood; Negi, P S

Abstract: National Physical
Laboratory India (NPLI) is the premier research and development centre and the
National Metrology Institute (NMI), which provides apex level calibration
services to the country. The coaxial microcalorimeter is used for assigning the
effective efficiency of the reference standard coaxial thermistor mount in the
frequency range 10 MHz-
18 GHz. Measurement technique for calibrating microwave power reference
standard has been presented. The calibration results and the various factors
influencing the results have been explained. All the measurements are performed
using a fully automated data acquisition system, which has been developed
indigenously in the laboratory. The uncertainty components in assigning the
effective efficiency using calorimeter system have been discussed. The
calibration uncertainty, which is a function of frequency ranges from 0.2 per
cent at 10 MHz to 0.7 per cent at 18 GHz.

Page(s): 170-174 2014/03/04 - 15:45

Title: Theoretical study of transport of heat through amorphous helical polymers

Authors: Dashora, P; Dashora, J; Gupta, G; Parnami, U

Abstract: A study of transport of heat
through non-conducting amorphous helical polymers is presented. Predominant
phonon scattering processes have been identified on the basis of general
structural features and the effect of temperature on these. Accordingly, relations
have been deduced for the dependence of the thermal conductivity λ on
temperature T. It is shown that the glass

transition temperature Tg of polymers can also be predicted
through the conductivity trends, estimated values of Tg of PMMA, PIB and PTFE are quite close to the reported
ones. Present study reveals that the helical polymers fall in 'group A' of the classification
of linear polymers proposed recently by the authors (Polymer 37, (1996),
231). Calculated values of λ, of five

different isotropic polymers viz.
PIB, PTFE, PCTFE, PET and PMMA, over a wide range of temperature (90- 370 K), are
in excellent agreement with the available experimental data (maximum deviation
is 4%). Proposed theory also explains the effect of extrusion on the thermal
conductivity. Theoretically computed values of thermal conductivities of
extruded PMMA in the

draw direction All
and in the perpendicular to the draw direction λ┴ agree well with the
reported experimental values. Maximum deviation being 2%.

Page(s): 29-33 2014/02/27 - 19:47

Title: Evaluation of line width (damping) of zero-sound mode in liquid 3He

Authors: Mishra, S; Mishra, L K

Abstract: Using the phonon part of the effective
Hamiltonian of Mishra and Tripathy [J Low Temp Phys. 75 (1989) 79], we
have evaluated the linewidth Γk of the zero-sound mode as a function
of the momentum transfer k for liquid .3He by two methods is evaluated.
Introducing a parameter for local field correction. our calculated values Of Γk
are good agreement with the experimental data.

Page(s): 20-24 2014/02/27 - 19:47

Title: Thermodynamic parameters of antifungal 3,4,5-trimethoxy benzaldehyde thiosemicarbazone

Authors: Yadav, B S; Kumar, Vipin; Singh, Vir; Semwal, B S

Abstract: The vibrational Spectrum and antifungal activity of 3,4,5-
trimethoxybenzaldehyde thiosemicarbazone have been reported.The thermodynamic functions
have been calculated using the IR frequencies. The group sensitive fundamentals
are compared with those of similar molecules already reported in the literature.
The antifungal activity of the said compound has been screened against
Rhizopus, Aspergillus nidulence, Aspergillus flavus, Aspergillus niger and Alternaria

Page(s): 34-41 2014/02/27 - 19:47

Title: Performance degradation of an optical Costas loop due to non-ideal response of 90° hybrid

Authors: Sarkar, B C; Hati, (Ms) R

Abstract: Effect of non-ideal response of a 90° hybrid in optical Costas loops has
been examined. Even a very slight phase deviation ψ, from the ideal hybrid
phase shift of 90° leads to increased power penalties and receiver
sensitivities. Choice of the optimum power splitting ratio leading to a minimum
BER, for a fixed laser linewidth, also increases. The greater the magnitude of
the phase deviation, the more the system performance degradation. The nature of
these variations does not depend significantly on the number of in-line optical

Page(s): 66-72 2014/02/27 - 19:47

Title: Determination of phase correction arising at the interface of base platen and slip gauge material in gauge- interferometry

Authors: Karfa, Mrityunjay

Abstract: In gauge- interferometry if the gauge material and the
base platen material are different the optical length O and particle
length L no longer remains the same and phase correction is to be
introduced so that L = O+. In the commonly used method is found out
by selecting 5 different lengths of slip gauges and finding-out one-fourth of
the difference between the combined optical length, measurement being carried
out at a different temperature and for that matter at different matter
conditions. This method encompasses the problem of observation at different
temperature as well at different environment conditions and naturally embraces
the possibility of errors associated with all the different temperature as well
as all the associated environment parameters. In the method devised and
discussed here. this problem has been taken care of very well and the gauges under
observation have been subjected to the same temperature and same environmental
conditions, so that the contribution or these factors towards the measurement
is drastically reduced and the measurement 
error remains the minimum possible.

Page(s): 6-9 2014/02/21 - 17:33

Title: Photophysics of exciplex emission of crystalline biphenyl doped by pyrene

Authors: Jadhav, S A; Pujari, S R; Patil, S R

Abstract: Fluorescence
in crystalline biphenyl powder containing pyrene impurity has been
studied at room temperature. The florescence spectrum of biphenyl luminophore
containing 10-3 mole pyrene shows structured monomeric emission of pyrene.

The increase in concentration
of pyrene quenches the structured monomer emission due to non radiative transfer
of energy from excited pyrene to biphenyl. At the higher concentrations, the expected
lateral overlapping of p-molecular orbits modify the spectrum as broad structureless.
The broad fluorescence band of biphenyl containing 10-1   mole
pyrene is cantered at 458 nm . The well known excimer emission of crystalline pyrene
is not observed in the fluorescence spectrum. Hence the red shifted broad and
structureless emission is attributed to the exciplex formed in the excited state
between biphenyl and pyrene.

Page(s): 43-47 2014/02/21 - 17:33

Title: Self-focusing of an ultra-intense short-pulse laser beam in a tunnel-ionized plasma

Authors: Gupta, G P; Abrol, V

Abstract: Tunnel-ionized plasma evolve on a time scale shorter than
the duration of an ultra-intense short-pulse laser beam propagating through
matter. Self-focusing of a linearly polarized laser beam with a parabolic
intensity distribution in a tunnel-ionized plasma produced during its
propagation through a gas is studied under the paraxial ray approximation. The
Laplacian term of the electric field in the electromagnetic wave equation has been
evaluated using two approaches, one leading to the more accurate expression for
the beam-width parameter f  and
the other leading to the less accurate expression for f. Analyzing these
expressions along with that reported in the literature for a Gaussian
laser  beam it is observed that the
expressions obtained in this paper predict the increasing axial intensity with
the distance of propagation (self focusing) in contrast to the result
(self-defocusing) predicted from the earlier reported expression.

Page(s): 1-5 2014/02/21 - 17:33

Title: Structural and electrical characterisation of polymeric electrolytes: PVA-NH4SCN system

Authors: Agrawal, S L; Shukla, P K

Abstract: The
structural and ion transport studies on PVAx:NH4SCN solid
polymer electrolytes (SPEs) with the aim of developing suitable proton
conducting electrolyte for solid stable ionic devices have been reported. DSC,
XRD and IR analysis of synthesised films have been carried out to study
morphology and complexation behaviour
of PVA with NH4SCN. A possible structure of PVA complex
has been proposed on the basis of IR spectroscopy. The electrical
characterisation which comprise, of I-t, coulometry, TIC measurements
and impedance spectroscopy has been carried out to assess ion transport
behaviour of these complexes. The electrical measurements evidenced cationic
transport with a maximum in electrical conductivity of 7.0 ×10-5 S
cm-1 for x=0.15

in the system. The
compositional variation of ionic conductivity has been correlated to morphology
and concentration of charge carriers.

Page(s): 53-61 2014/02/21 - 17:33

Title: Electrical resistivity behaviour of reentrant amorphous Fe-Zr based alloys

Authors: Perumal, A; Srinivas, V; Rao, V V

Abstract: The temperature dependence of the electrical resistivity of a- Fe100-xZrx
 alloys (x= 8.5,9.5 and 10) and a-Fe86Mn4Zr10
 in the temperature range 5-300 K has
been reported. The resistivity is round 10 decreases as the temperature is
raised and goes through a minimum at a particular temperature (Tmin). Tmin is observed at around Curie temperature of that
particular composition. Our observations indicate some correlation between
magnetic and electrical resistivity behaviour near the transition region. A
quantitative analysis based on both magnetic and non-magnetic scattering models
has been carried out in order to quantify the contributions from these
scattering processes, It is found that the magnetic contribution is noticeable
around transition temperature in addition to the dominant non-magnetic
contribution, it is found that in addition to magnetic scattering, non-
magnetic scattering a critical scattering mechanism is also required to explain
the complete range or experimental data.

Page(s): 35-42 2014/02/20 - 08:07

Title: Photon energy dependent irradiation effects in a Cu(I) containing silica glass: The phenomenon and its applications

Authors: Debnath, R

Abstract: Copper(I) ions in a silica glass
upon irradiation either with UV (4-5 eV ) or with high energy photons like γ
ray are found to produce copper-related electron deficient species in the
matrix. In the  case of UV irradiation, formation
of isolated divalent copper species has been clearly revealed, while in the case of γ- irradiation,
generation of a copper related ionized center of the type |AlO/Cu++|+is evident. The difference observed in the effect of photons
of two different energies on the same has been ascribed to two different modes of electron movement in
the matrix under the two different energetic irradiation of the glass. The importance of the
phenomenon with reference to its applications in opto-electronics and optical sensing
has been discussed.

Page(s): 26-34 2014/02/20 - 08:07

Title: Ultrasonic studies in dilute solutions of water and nonelectrolytes

Authors: Ramana, G Venkata; Rajagopal, E; Murthy, N Manohara

Abstract: Ultrasonic velocities in dilute solutions of water
in n-propanol, isopropanol, glycerol, formamide. N-methyl formamide, dimethyl formamide
tetrahydrofuran and propylene glycol have been determined 298.15 K using single
crystal variable path interferometer working at 3 Mhz. Excess sound velocities,
have been evaluated using the formula which is
thermodynamically valid. Both the ultrasonic velocity and excess ultralsonic
velocity have been found to vary nonlinearly with concentration in the high
dilution range of water in non electrolytes studied. The results are explained
by considering the existence of water molecules as
monomer up to certain optimum concentration (X2)opt of
water and the nonlinear behaviour observed beyond (X2)opt has been explained in the
light water-water and water- nonelectrolyte interactions leading to the
formation of island of water-nonelectrolyte complexes.

Page(s): 10-14 2014/02/20 - 08:07

Title: Optimization and deciding the geometry of W -cell: (i) Effect of diameter and (ii) effect of central height

Authors: Kshirsagar, S R; Bhile, Arvind M

Abstract: The optimization or experimental conditions for the
electrochemical purification or brackish water to potable water has been reported. It has been found that the electrolysis at 550 V or dirty water in a W-cell of
central diameter or 15 mill and central height or 200 cm gives optimum yield or
potable water with minimum consumption or electrical energy.

Page(s): 22-25 2014/02/20 - 08:07