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51.
Ramesh K. Asokan S. Sangunni K.S. Gopal E.S.R. 《Applied Physics A: Materials Science & Processing》1999,69(4):421-425
Electrical switching in germanium telluride glasses containing metallic atoms (Cu and Ag) has been investigated. All these
glasses are found to exhibit memory switching. The switching fields of these glasses are compared with the thermal parameters
evaluated from DSC studies and the results are explained on the basis of the thermal model. The composition dependence of
the switching field and the thermal parameters show interesting variations at the critical compositions which correspond to
the rigidity percolation and the chemical thresholds of these glasses.
Received: 11 January 1999 / Accepted: 14 April 1999 / Published online: 14 July 1999 相似文献
52.
Vidhu VK Aromal SA Philip D 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,83(1):392-397
Green synthesis of noble metal nanoparticles is a vast developing area of research. In this paper we report the green synthesis of silver nanoparticles using aqueous seed extract of Macrotyloma uniflorum. The effect of experimental parameters such as amount of extract, temperature and pH on the formation of silver nanoparticles was studied. The as prepared samples are characterized using XRD, TEM, UV-Visible and FTIR techniques. The formation of silver nanoparticles is evidenced by the appearance of signatory brown colour of the solution and UV-vis spectra. The XRD analysis shows that the silver nanoparticles are of face centered cubic structure. Well-dispersed silver nanoparticles with anisotropic morphology having size ~12 nm are seen in TEM images. FTIR spectrum indicates the presence of different functional groups in capping the nanoparticles. The possible mechanism leading to the formation of silver nanoparticles is suggested. 相似文献
53.
Philip D Unni C Aromal SA Vidhu VK 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,78(2):899-904
A facile bottom-up 'green' and rapid synthetic route using Murraya Koenigii leaf extract as reducing and stabilizing agent produced silver nanoparticles at ambient conditions and gold nanoparticles at 373 K. The nanoparticles were characterized using UV-vis, transmission electron microscopy (TEM), X-ray diffraction (XRD) and FTIR analysis. This method allows the synthesis of well-dispersed silver and gold nanoparticles having size ~10 nm and ~20 nm, respectively. Silver nanoparticles with size ~10 nm having symmetric SPR band centered at 411 nm is obtained within 5 min of addition of the extract to the solution of AgNO3 at room temperature. Nearly spherical gold nanoparticles having size ~20 nm with SPR at 532 nm is obtained on adding the leaf extract to the boiling solution of HAuCl4. Crystallinity of the nanoparticles is confirmed from the high-resolution TEM images, selected area electron diffraction (SAED) and XRD patterns. From the FTIR spectra it is found that the biomolecules responsible for capping are different in gold and silver nanoparticles. A comparison of the present work with the author's earlier reports on biosynthesis is also included. 相似文献
54.
K. ElayarajaM.I. Ahymah Joshy R.V. SuganthiS. Narayana Kalkura M. PalanichamyM. Ashok V.V. SivakumarP.K. Kulriya I. SulaniaD. Kanjilal K. Asokan 《Applied Surface Science》2011,257(6):2134-2141
Titanium substrate was coated with hydroxyapatite by radiofrequency magnetron sputtering (rf-magnetron sputtering) technique and subjected to swift heavy ion (SHI) irradiation of 125 MeV with Si9+ at fluences of 1 × 1010, 1 × 1011 and 1 × 1012 ions/cm2. The glancing incidence X-ray diffraction (GIXRD) analysis confirmed the HAp phase of the irradiated film. There was a considerable decrease in crystallinity and particle size after irradiation. In addition, DRS-UV reflectance spectra revealed a decrease in optical band gap (Eg) from 5.2 to 4.6 eV. Wettability of biocompatible materials plays an important role in biological cells proliferation for tissue engineering, drug delivery, gene transfer and bone growth. HAp thin films irradiated with 1 × 1011 ions/cm2 fluence showed significant increase in wettability. While the SHI irradiated samples exhibited enhanced bioactivity, there was no significant variation in cell viability. Surface roughness, pores and average particle size were analyzed by atomic force microscopy (AFM). 相似文献
55.
Aditya Sharma K. D. Verma Mayora Varshney Devendra Singh Moti Singh K. Asokan 《辐射效应与固体损伤》2013,168(12):930-937
In this paper, we present the impact of swift heavy ion beam irradiation on the structural, optical and electronic properties of SnO2 thin films. Thin films were deposited using the pulsed laser deposition technique on Al2O3 substrates. Atomic force microscopy, X-ray diffraction, UV–visible absorption and temperature-dependent resistivity measurements were performed to explore the morphological, structural, optical and electronic properties of the as-deposited and irradiated samples. The peak intensity of the (200) peak was found to decrease monotonously with increasing irradiation fluence. The band gap energy of the 1×1011 ion/cm2 irradiated sample was found to increase. The electrical resistivity of the samples showed a continuous increase with the irradiation fluence. 相似文献
56.
Abstract Bulk, semiconducting GaxTe100-x (17 ≤ x ≤ 25) glasses are prepared by the meltingh quenching method and electrical resistivity measurements are carried out at high pressures up to 8 GPa and low temperatures down to 77 K in a Bridgman anvil system. It is found that all the GaxTe100-x, glasses exhibit metallization under pressure, with a continuous decrease in electrical resistivity and activation energy for conduction. Further, the high pressure metallic phases of GaxTe100-x samples are found to be crystalline. 相似文献
57.
Divya Singh Amit Saxena Shri Prakash Pandey Sandeep Kumar Tomar K. Asokan D. Kanjilal Ranvir Kumar Bhaskar Bhattacharya 《Macromolecular Symposia》2009,277(1):8-13
In this paper, we report the ion beam interaction with a well explored ion conducting polymer electrolyte, viz., polyethylene oxide complexed with sodium iodide (PEO:NaI). Li3+ ions at 50 MeV were bombarded on the film at different flux. The conductivity modulation of the films has been reported due to interaction at different fluence. The increase in the total conductivity is explained in terms of the change in the number of charge carriers and the dielectric constant of the polymer electrolyte films. 相似文献
58.
Electrical switching studies on bulk Ge10Se90−xTlx (15 ? x ? 34) glasses have been undertaken to examine the type of switching, composition and thickness dependence of switching voltages. Unlike Ge-Se-Tl thin films which exhibit memory switching, the bulk Ge10Se90−xTlx glasses are found to exhibit threshold type switching with fluctuations seen in their current-voltage (I-V) characteristics. Further, it is observed that the switching voltages (VT) of Ge10Se90−xTlx glasses decrease with the increase in the Tl concentration. An effort has been made to understand the observed composition dependence on the basis of nature of bonding of Tl atoms and a decrease in the chemical disorder with composition. In addition, the network connectivity and metallicity factors also contribute for the observed decrease in the switching voltages of Ge10Se90−xTlx glasses with Tl addition. It is also interesting to note that the composition dependence of switching voltages of Ge10Se90−xTlx glasses exhibit a small cusp around the composition x = 22, which is understood on the basis of a thermally reversing window in this system in the composition range 22 ? x ? 30. The thickness dependence of switching voltages has been found to provide an insight about the type of switching mechanism involved in these samples. 相似文献
59.
S. Chandramohan R. Sathyamoorthy P. Sudhagar D. Kanjilal D. Kabiraj K. Asokan V. Ganesan T. Shripathi U. P. Deshpande 《Applied Physics A: Materials Science & Processing》2009,94(3):703-714
The effect of high electronic energy deposition on the structure, surface topography, optical properties, and electronic structure
of cadmium sulfide (CdS) thin films have been investigated by irradiating the films with 100 MeV Ag+7 ions at different ion fluences in the range of 1012–1013 ions/cm2. The CdS films were deposited on glass substrate by thermal evaporation, and the films studied in the present work are polycrystalline
with crystallites preferentially oriented along (002)-H direction. It is shown that swift heavy ion (SHI) irradiation leads
to grain agglomeration and hence an increase in the grain size at low ion fluences. The observed lattice compaction was related
to irradiation induced polygonization. The optical band gap energy decreased after irradiation, possibly due to the combined
effect of change in the grain size and in the creation of intermediate energy levels. Enhanced nonradiative recombination
via additional deep levels, introduced by SHI irradiation was noticed from photoluminescence (PL) analysis. A shift in the
core levels associated with the change in Fermi level position was realized from XPS analysis. The chemistry of CdS film surface
was studied which showed profound chemisorption of oxygen on the surface of CdS. 相似文献
60.
Ramkumar Govindaraju Asokan Ramasamy Ramya Suseenther Gayathri Ganeshan 《Journal of Cluster Science》2021,32(5):1185-1190
Journal of Cluster Science - Indiscriminate use of synthetic chemicals for pest management in agriculture leads to resistance development by the pests in addition to being toxic to non target... 相似文献