[en] Highlights: •Nano-crystalline BST films were obtained on amorphous fused silica substrates. •Crystallization was induced by quasi-RTA, a cost effective approach. •No evidence of residual strain or surface layer was observed in the annealed films. •Dielectric properties @10 GHz were measured using split post dielectric resonator. •Crystallization result in higher density, conductivity, dielectric const. and tan δ. -- Abstract: Thin films of (Ba_0.5,Sr_0.5)TiO₃ (BST5) were deposited at ambient temperature on fused silica substrates by RF magnetron sputtering technique. Nano-crystalline films were obtained upon quasi-rapid thermal annealing (Q-RTA) at temperatures ⩾800 °C for 60 s. The influence of Q-RTA temperature on the structural, morphological, optical and microwave dielectric properties of BST5 thin films have been investigated. The as-deposited and Q-RTA films annealed up to 700 °C were amorphous in nature. On increasing the Q-RTA temperature to 800 °C and above resulted in an amorphous–crystalline phase transition in the films. All the crystalline films show similar full width at half maxima (FWHM) and hence, similar crystallite size of about 12 ± 1 nm. The amorphous–crystalline transition was accompanied by a decrease in the optical band gap from 4.5 to 3.6 and increase in the refractive index from 1.9 to 2.2 as well as in the microwave dielectric constant from 40 to 262. The Root Mean Square roughness (RMS_roughness) as measured from AFM show an increase from 0.6 nm to 5.6 nm with an increase in Q-RTA temperature from 400 °C to 1000 °C

[en] Highlights: • An architecture featuring carbon coated, interconnected nano-grains was constructed with mesopores for LiMnPO₄/C cathodes. • Mesoporous LiMnPO₄/C delivers 140 mAh g⁻¹ at 0.05 C, one of the best storage performances in galvanostatic charge/discharge mode. • Interdependence of storage performance on carbon, milling time, grain size, surface area, pore size and pore volume is elucidated. • Feasible full cell operation with Li₄Ti₅O₁₂/C anode. -- Abstract: An architecture featuring carbon coated, interconnected nano-grains constructed with mesopores is developed for LiMnPO₄ cathode material. This architecture facilitates enhanced lithium ionic and electronic transports; favours improved lithium storage performance. Mesoporous LiMnPO₄/C electrode delivers discharge capacity of 140 mAh g⁻¹ at 0.05 C using galvanostatic cycling mode. This best electrochemical response of LiMnPO₄/C at constant current mode is complemented by diffusion studies using cyclic voltammetry and impedance spectroscopy. Further, the interdependence of lithium storage performance on carbon content, milling time (2, 4, 6 and 10 h), grain size and porous characteristics (surface area, pore size and pore volume) is also discussed. Finally, the feasibility of LiMnPO₄/C cathode is evaluated against Li₄Ti₅O₁₂/C anode in a full cell

[en] In experiments like ion implantation based ion track formations, the sample is implanted to low doses of the order of 10¹⁰ ions/cm², limiting the ion beam currents to be less than 1-5 x 10^-12A. However the standard current integrators available are not sensitive to very low currents, causing an unacceptable high level of error in dose measurement. Hence a low dose implantation measurement system has been developed. It consists of a very sensitive low current preamplifier with full scale input 1nA/100pA, a standard current integrator, a microcontroller based interface circuit, which are connected to a personal computer(PC) through USB. Two types of the software are developed for the system: the microcontroller firmware using C and windows based virtual instrument programs using LabVIEW 7.0. Necessary precautions associated with pA level measurement like rigidly fastened good quality cables, low ripple DC power supply, shielding, close mounting of the preamplifier to the sample are adopted. After necessary calibrations with an ECIL make low current source, the system has been put into regular use. Design and development details, salient features are discussed in this paper. (author)

[en] A study with gamma irradiation and along with 1.0% EMS was undertaken with the rice variety PY 5. Seeds were irradiated with gamma irradiation dose of 5, 10, 15 and 20 kR and along with 1.0% of EMS. The M₁ and M₂ generations were grown during Navarai and Kuruvai, respectively. Maximum increase was noticed at 20 kR+1.0% EMS treatment for all the characters viz., plant height, leaf area index, dry matter production, harvest index and grain yield per plant. Maximum heritability was observed at 20 kR treatment and genetic advance at 5 kR treatment. Maximum PCV and GCV were observed for plant height at 20 kR, leaf area index and harvest index at 5 kR treatment. (author)

[en] The effect of substrate temperature on the crystallographic texture and surface morphology of Ba_0.5Sr_0.5TiO₃ deposited by rf magnetron sputtering on (111) oriented Pt (150 nm)/Ti (10 nm)/SiO₂ (300 nm)/Si (100) substrates is reported. The onset of crystallinity is observed above 500 deg. C, beyond which all films are oriented along the (111) plane up to a temperature of 800 deg. C. Over this temperature range, the misfit strain and root mean square roughness (rms_roughness) peak at 600 deg. C, decreasing beyond this peak value. The tunability of the dielectric constant at 100 kHz is highest (60% for a field strength of 300 kV/cm) at the lowest values of rms_roughness and misfit strain and decreases as these values increase. It is also shown that the morphology of the Pt underlayers is strongly affected by the processing conditions. This in turn influences the tunable behavior of the BST films as much as the substrate temperature during growth and the consequent microstructural variations.

[en] There are not much experimental works on the interaction of O with defects in FeCr alloys. The O¹⁸ ion is implanted in bee Fe 15%Cr (100) alloy single crystal and annealed. The lattice location of O¹⁸ is measured using nuclear reaction analysis and channeling experiments and simulations. The O¹⁸ is found to be at site-X which is midway between substitutional and octahedral interstitial site displaced 0.6Å from octahedral interstitial site. Upon introducing excess vacancy defects by Fe self ion implantation, O¹⁸ is found to shift from site-X to site-Y which is displaced 1 Å along <110> direction from octahedral interstitial site. The type of defects is found to be dislocation loops by energy dependent dechanneling measurements. Our study provides strong evidence of O-vacancy clusters survived in the form of O-dislocation loops produced during irradiation and annealing. (author)

[en] (Ba_0.5, Sr_0.5)TiO₃ thin films have been prepared by the sol-gel technique. A correlation between the evolution of optical constants and structure shows that the refractive index and optical band gap approach the values corresponding to the bulk stoichiometric compound only at temperatures greater than 600 deg C. The onset of crystallinity (at 600 deg C) is accompanied by an increase in refractive index and decrease in optical band gap. Beyond 600 deg C the films approach the bulk band gap value of 3.6 eV with a maximum refractive index of 2.05 in the region between 500 and 1000 nm as against the 1.75 at 500 deg C. These results clearly indicate that complete oxidation and crystallization occurs at temperature ≥ 600 deg C. (author)

[en] We report the photoresponse performance of plasmonic nickel (Ni) nanoparticles (NPs)-decorated ZnO NR arrays-based ultraviolet (UV) surface photodetectors. The ZnO NR arrays were grown on the Si substrate by the facile hydrothermal method, followed by Ni NP decoration on the surface by pulsed laser deposition (PLD) technique. Raman analyses reveal that the grown ZnO NR arrays are in hexagonal wurtzite structure. The field emission scanning electron microscopy (FE-SEM) shows that the grown ZnO NR arrays are vertically aligned, hexagonal faceted, and uniformly distributed on the Si substrate. The 14-fold enhancement in the UV emission upon Ni NP decoration implies the near-field coupling of surface plasmons (SPs) of Ni NPs with the excitons of ZnO NRs. The linear increase in current with the applied voltage indicates good Ohmic contacts between the ZnO NR arrays and the Ag electrodes. The transient photo-response measurements were performed for every twenty seconds (20 s) ON/OFF time and for nine cycles to study its response speed, stability, and repeatability of the photodetectors. The improved photo-response of the Ni NP-decorated ZnO NR arrays is attributed to the near-field coupling of Ni NPs with the underlying ZnO NRs. The decoration of plasmonic Ni NPs provides better optical pathway for the incident light and transfers its hot electrons to the conduction band of ZnO NR arrays gives rise the improved photoresponse.

[en] A simple low temperature ion implantation and ion channeling facility has been set up. Low temperatures upto 70 K has been obtained on a goniometer sample holder by connecting to a continuous flow Helium cryostat with a copper braid. Charge integration is carried out with a transmission Faraday cup with 10 mm diameter aperture and four Faraday cups for performing ion implantation and an electron suppressed 1.5 mm aperture with a TEM grid of 60% beam transmission for ion beam analysis. Typical low temperature ion implantation and channeling experiments have been carried out. Stabilization at intermediate temperatures by controlling the heater at the sample holder and improvement of the achievable lowest temperature by having liquid nitrogen cooled heat shield are in progress.

[en] A 1.7MV Tandetron accelerator at Materials Science Group of IGCAR is regularly used for carrying out radiation damage studies, particle irradiation based materials research. A dual beam irradiation facility is being setup which uses heavy ion beam from the 1.7 MV Tandetron accelerator through the 30 ° beam line and helium ion beam from a 400 kV accelerator. In the beam line, a set of beam handling devices such as quadrupole focus lens and electrostatic steerers with +/-30 kV and +/-10 kV power supplies are used to focus and steer the ion beam. A PIC16F877A microcontroller (UC) based embedded system has been developed to facilitate remote control and monitoring of these power supplies from the control PC of the Tandetron accelerator, resulting in improved focusing and fine tuning of the ion beam. The prototype of the embedded system was designed, developed, tested and installed in the beam line. The system works satisfactorily and is under regular use. Working principle, design details, salient features of the embedded system are discussed in the paper. (author)