An International Research Journal

AJP Vol 25 No 8

AJP

SSN : 0971 - 3093

Vol 25, No 8, August, 2016

25th Anniversary Year of AJP-2016


Asian Journal of Physics                                                                                                        Vol. 25 No 8, 2016, 00-00


Enhanced Thermal Conductivity in Nanowire Doped Copper Selenide


Ranu Bhatt1,*, Anil Bohra1, Gopika Krishnan1, 2, Shovit Bhattacharya1, Ranita Basu1, A.K. Debnath1, Ajay Singh1, D.K. Aswal1, 3, K.P. Muthe1, S.K. Gupta1

1Technical Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai – 400085

2 Indian Institute of Science Educations and Research, Thiruvantahapuram – 695016

3National Physical Laboratory, K.S. Krishnanan Marg, Pusa, New Delhi-110012

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In present work, we have investigated the effect of Cu2-xSe nanowire (NW) doping (0-15 wt. %) on the structural and thermal transport properties of mechanically alloyed Cu2Se nanopowder. The synthesis of Cu2-xSe NW was carried out using the surfactant-free aqueous route. The morphology and composition of the NW was studied using scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDX). The X-ray diffraction (XRD) of the NW shows the formation of cubic Cu2-xSe phase along with presence of Cu2SeO3 as a minority secondary phase. The optical band gap (Eg) of the NW calculated using UV-vis spectra was found to be indirect band gap of 0.51 eV. Chemical composition and binding energy (B.E.) of the samples were studied using X-ray photoelectron spectroscopy (XPS) suggests the formation of copper oxide in addition of copper selenide in the sample. The thermal transport measurement shows drastic enhancement in the thermal conductivity (κ) of the sample with increasing NW content in temperature range of 30- 300º C. This enhancement in κ may be attributed to; (i) the suppression of α-β phase transformation and (ii) percolation path provided by the doped NW’s. © Anita Publications. All rights reserved.

Total Refs : 16

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16.  T.A.Marry, J. Jesudurai, A simple hydrothermal route for synthesizing copper Selenide Nano-Flakes, Elixir Nanocomposite Materials, 50 (2012) 10499-10500.

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Asian Journal of Physics                                                                                                        Vol. 25 No 8, 2016,00-00


Improved H2S Sensing Characteristics of Al Modified SnO2 Thin Films


Deepak. Goyal, Niranjan S. Ramgir*, C. P. Goyal, A. K. Debnath, K. P. Muthe, S. K. Gupta

Thin Films Devices Section, Technical Physics Division, BARC, Mumbai

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H2S sensing properties of pure and Al modified SnO2 thin films prepared by RGTO method have been investigated. Both the sensor films exhibited maximum sensor response at an optimal operating temperature of 200°C. SnO2 film modified with 5 nm thick Al exhibited higher and selective sensor response of 4.4 as compared to that of 2.1 for pure SnO2 film towards 20 ppm of H2S at an operating temperature of 200°C. Al modification enhanced the sensing characteristics due to spillover mechanism. © Anita Publications. All rights reserved.

Keywords: SnO2, Al sensitizer, Gas sensor, H2S, Metal oxides, Thin films

References

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Asian Journal of Physics                                                                                                        Vol. 25 No 8, 2016,00-00


H2S sensing behavior of MOS thin film of titanium oxide


Nagmani1, T C Jagadale1*, C L Prajapat1, N S Ramgir1, K P Muthe1 and S C Gadkari1

1Technical Physics Division, Bhabha Atomic Research Centre, Mumbai- 400 085, India.

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We report the pulsed laser deposited titanium oxide thin film for H2S sensing. These films were prepared on STO substrate using laser energy 500 mJ. The surface and bulk electronic structures were revealed using X-ray photo-electron spectroscopy technique, whereas the crystal quality and chemical composition of the film was investigated by X-ray diffraction. These films showed very good selectivity to H2S with response of about ~ 760% at 250oC operating temperature with much better response and recovery time. With increase in sensor operating temperature, response to H2S has improved due to increase in number of active sites on the film surface which facilitates the chemisorptions of ambient oxygen. © Anita Publications. All rights reserved.

Keywords: SnO2, Al sensitizer, Gas sensor, H2S, Metal oxides, Thin films

References

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Asian Journal of Physics                                                                                                        Vol. 25 No 8, 2016,00-00


NH3 sensing properties of doped and co-doped TiO2-polyaniline nanocomposite films


U V Patil1,3, Niranjan S Ramgir2*, R Jaiswal, N Patel, A K Debnath2, K P Muthe2, S K Gupta2 and D C Kothari3

1Wilson College, Chowpatty, Mumbai-400 007, India

2Technical Physics Division, Bhabha Atomic Research Centre, Mumbai-400 085, India

3Department of Physics, University of Mumbai and National Centre for Nanosciences & Nanotechnology, Santacruz (E), Mumbai- 400 098, India

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Ammonia sensing properties of nanocomposite (NC) films of conducting polyaniline (PANI) intercalated with TiO2, doped and co-doped with TiO2 nanoparticles have been studied. The response characteristics of NC films towards different gases namely NH3, CO, CO2, and C2H5OH were examined at room temperature. Both pure PANI and NC films exhibited a selective response towards NH3. It was observed that NC film exhibits better sensor response and response kinetics as compared to pristine PANI films. PANI intercalated with TiO2 (PANI-TiO2) NC film shows fourfold increase (76%) in response towards 50 ppm NH3 as compared to threefold increase (65%) shown by pristine PANI sensor film. The PANI intercalated nitrogen doped TiO2 (PANI-N4-TiO2) NC film shows fivefold increase (80%) in response to 50 ppm ammonia. The response and recovery times of PANI-TiO2 NC film are 6 and 370 s, respectively, while for PANI-N4-TiO2 NC films were 2 and 670 s, respectively. These values are better than that exhibited by pristine PANI sensor film (6 and 960 s). The enhanced response kinetics is mainly attributed to the structural modification with high porosity and surface area of NC sensor film.© Anita Publications. All rights reserved.

Keywords: Conducting PANI, nanoparticles, nanocomposite (NC), Ammonia, Gas sensors

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Asian Journal of Physics                                                                                                        Vol. 25 No 8, 2016, 977-983


Tailoring thermal conductivity in SnSe by AgSbTe2 addition


Shovit Bhattacharya1*, Mandira Majumder1, 2, Ranu Bhatt1, Sudhindra Rayaprol3, Ranita Basu1, Anil Bohra1, Ajay Singh1 and D K Aswal1

1Technical Physics Division, B.A.R.C., Trombay, Mumbai- 400 085

2Department of Applied Physics, Indian School of Mines, Dhanbad- 826 004

3UGC-DAE CSR, Mumbai Center, R-5 Shed, BARC, Trombay, Mumbai-400 085

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Lead free materials have gained considerable interest in the field of Thermoelectrics due to environmental issues. SnTe is an interesting alternative to the well established PbTe as an efficient thermoelectric material, owing to similar electronic and structural similarity. Conversely, the biggest challenge in SnTe is the intrinsically high carrier concentration due to substantial Sn vacancies, which is extremely unlikely to be overcome by chemical substitutions. In this perspective, composites of (SnTe)1-x(AgSbTe2)x [x = 0, 0.25, 0.5, 0.75 and 1] were prepared in order to tailor its thermal conductivity. In this paper we report the suppression of the thermal conductivity as a function of increasing concentration of AgSbTe2 in the composite. © Anita Publications. All rights reserved.

Keywords: Thermoelectric material, thermal conductivity.

Total Refs: 8

    1.    D. M. Rowe, CRC Handbook of Thermoelectrics, Boca Raton, FL: CRC Press, 1996
    2.    C. Kittel, Introduction to Solid State Physics, Wiley, Singapore 1996.
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Asian Journal of Physics                                                                                                        Vol. 25 No 8, 2016, 993-998


 H2S sensing properties of ZnO microcrystals having almond morphology


Savita Dange1*, S N Dange2, N S Ramgir3 and P S More1

1Department of Physics, The Institute of Science, M.C.Road, Fort, Mumbai-400 032, India

2Department of Physics, Jai Hind College, ‘A’ Road , Churchgate, Mumbai-400 020, India

3Technical Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India

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Gas sensing properties of zinc oxide microcrystals having almond like morphology have been investigated towards H2S gas. Uniform thin film of almond like microcrystals of zinc oxide was synthesised by using chemical bath deposition method at room temperature. The almond microcrystals show average tip size of about 100 nm and length of about 1.5 μm. The ZnO film was tested for H2S gas having 50 ppm concentration for temperatures upto 300°C. The film showed highest percentage response at 250°C and fast response and recovery time at 300°C. The structural and optical properties of the ZnO film were characterized by X-ray diffraction (XRD), UV-Vis and Scanning electron microscopy (SEM). © Anita Publications. All rights reserved.

Keywords: Zinc oxide, Almond morphology, Micro crystals, H2S gas sensor, Response time.

Total Refs : 15

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IJIRSET, August 2015.
    9.    S.S.Dange, S.N. Dange, P.S.More, “Effect of pH on morphology of Cu added ZnO nanostructures by precipitation method.” IJIRSET, September 2015
    10.  E.Comini, G.Faglia, G.G.Sberveglieri, “ Solid State Gas Sensing ” Springer,2009
    11.  Yamazoe, N. Approaches for improving semiconductor gas sensor. Sens. Actuators B 1991, 5, 7–19.
    12.  N.S.Ramgir, S.S.Badadhe and I.S.Mulla, “H2S Gas Sensitive Indium-Doped ZnO Thin Films: Preparation and Characterization, Sensors and

Actuators B: Chemical, 143(2009)164-170
    13.  Z.T.Liu, T.X.Fan, D. Zhang, X.L.Gong and J.Q.Xu, “ Hierarchically Porous ZnO with High Sensitivity and Selectivity to H2S Derived from

Biotemplates,” Sensors and Actuators B:Chemical, Vol.136, No.2, 2009, pp. 499-509.
    14.  R.B. Slimane, F.S. Lau, R.J. Dihu, M. Khinkis, Production of hydrogen by superadiabaticdecomposition of hydrogen sulfide, in: Proceedings of the

2002 US DOEHydrogen Program Review, NREL/CP-610-32405, 2013.
    15.  P.P.Sahay, R.K.Nath, Sensors and Actuators B 134 (2008) 654-659

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Asian Journal of Physics                                                                                                     Vol. 25 No 8, 2016 1029-1036


A comparative study of the influence of vanadium pentoxide layer

on the ITO surface of organic light emitting diode


D Saikia* and R Sarma**

Thin Film Laboratory, Department of Physics, J. B. College, Jorhat, Assam, India

Pin code: 785001, Telephone: 8011468483, Fax:(0376)2300605

 

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In this paper the influence of vanadium pent oxide (V2O5) layer on the Tin-doped indium oxide (ITO) surface of organic light emitting diode has been reported. Here hole injection is directly affected by the different thicknesses of V2O5films on ITO surface. The ITO/V2O5(15 nm) bilayer anode shows better device performance compared to the bare ITO anode and that of the other thicknesses of V2O5 films. Enhanced device performance is due to the better transmittance property and lower surface resistivity of ITO/V2O5(15nm) bilayer anode combination. In this work N, N’-bis (3- methyl phenyl) - N, N’ (phenyl) -benzidine (TPD) is used as a hole transport layer and Tris (8-hydroxy quinolinato) aluminium (Alq3) as emitting layer. Our results indicate that the ITO/V2O5(15nm) bilayer anode is a better choice to enhanced the hole injection in OLED devices. Here we obtained maximum value of current and power efficiency as 5.6 Cd/A and 2.83 lm/W respectively. © Anita Publications. All rights reserved.

Keywords: Optoelectronics, Vanadium Pent oxide (V2O5), Indium tin oxide (ITO) and Figure of merit (FOM).

Total Refs : 23

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Prospect of molecular clocks
Masatoshi Kajita
National Institute of Information and Communications Technology
Koganei, Tokyo 184-8795, JAPAN
While uncertainties of some of the atomic transition frequencies have been reduced to the level of 10–8, the molecular transition frequencies are currently difficult to be measured with the uncertainty below 10–15. This is mainly because of the complicated energy levels of the molecules having the vibrational-rotational states. This paper lists some molecular transition frequencies, which can be measured with the uncertainties lower than 10–16. © Anita Publications. All rights reserved.

    

         Asian Journal of Physics                                                                                                     Vol. 25 No 8, 2016 00-00


Hydrothermally Grown SnO2 -RGO nanocomposites for H2 Gas Sensing Application


Bhagyashri Bhangare1, Shweta Jagtap1, Niranjan Ramgir2, Dinesh Aswal2, S.K.Gupta2, Suresh Gosavi1*

1 Department of Physics, Centre for Advanced Studies in Material Science and Solid State Physics,

Savitribai Phule Pune University, Ganeshkhind, Pune-411007, India.

2 Technical Physics Division, Bhabha Atomic Research Centre (BARC), Mumbai -400085, India

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The present paper describes the hydrothermal synthesis and characterization of reduced graphene oxide and tin oxide (SnO2/RGO) based nanocomposites. This route have gain more attention due to the eco-friendly i.e reducing agent free reduction of graphene oxide (GO). The SnO2/RGO nanocomposite was further used for hydrogen gas sensing application. The resultant gas sensor exhibits linear sensor response over the detectable range of 50-5000 ppm. In the present work, SnO2/RGO nanocomposite shows higher sensor response (Rair/Rgas) of about 275 towards 5000 ppm along with quick response time of 5 s and complete recovery within 250 s. The results obtained from experimental measurements were combined with second order reaction equation and pseudo second order reaction equation in order to describe the interaction of hydrogen molecules with the surface of the sensing material. © Anita Publications. All rights reserved.

References

  1.   “ A novel sensing mechanism for resistive gas sensors based on layered reduced graphene oxide thin films at room temperature”, Yong Zhou, Yadong Jiang, Tao Xie, Huiling Tai, Guangzhong Xie, Sensors and Actuators B 203 (2014) 135–142.

  2.   “Clean and highly ordered graphene synthesized in the gas phase”, Albert Dato, Zonghoon Lee, Ki-Joon Jeon, Rolf Erni, Velimir Radmilovic,Thomas J. Richardsonc and Michael Frenklachd, Chem. Commun., 2009, 6095–6097.

  3.   Sensing behavior of SnO2/reduced graphene oxide nanocomposites toward NO2” , Giovanni Neri, Salvatore Gianluca Leonardi, Mariangela Latino, Nicola Donato, Seunghwan Baek, Donato E. Conte, Patrícia A. Russo, Nicola Pinna, Sensors and Actuators B 179 (2013) 61– 68.

  4.   Sensing behavior of SnO2/reduced graphene oxide nanocomposites toward NO2”, Giovanni Neri,Salvatore Gianluca Leonardi, Mariangela Latino, Nicola Donato, Seunghwan Baek, Donato E. Conte, Patrícia A. Russo, Nicola Pinna, Sensors and Actuators B 179 (2013) 61– 68.

  5.   “Chemical vapor deposition repairof graphene oxide: a  to highly-conductive graphene monolayers”, Lopez V, Sundaram RS, Gomez-Navarro C, Olea D, Burghard M, Gomez-Herrero J, et al. Adv Mater 2009;21(46):46836.

  6.   “Catalytic hydrogen sensing using microheated platinum nanoparticle-loaded graphene aerogel”, Anna Harley-Trochimczyk, Jiyoung Chang, Qin Zhou, Jeffrey Dong, Thang Pham, Marcus A. Worsley, Roya Maboudian, Alex Zettl, Sensors and Actuators B 206 (2015) 399–406.

  7.   “Nanostructured Pt decorated graphene and multi walled carbon nanotube based room temperature hydrogen gas sensor”, Adarsh Kaniyoor, R. Imran Jafri, T. Arockiadoss and S. Ramaprabhu, Nanoscale, 2009, 1, 382–386.

  8.   “Hydrogen sensor based on a graphene – palladium nanocomposite”, Ulrich Lange, Thomas Hirsch, Vladimir M. Mirsky, Otto S. Wolfbeis, Electrochimica Acta 56 (2011) 3707–3712.

  9.   “Pd-WO3/reduced graphene oxide hierarchical nanostructures as efficient hydrogen gas sensors”, Ali Esfandiar , Azam Irajizad , Omid Akhavan ,Shahnaz Ghasemi , Mohammad Reza Gholami, International  journal of hydrogen energy 39(2014) 8169-8179.

10.   “Hydrogen sensor based on graphene/ZnO nanocomposite”, Kanika Anand, Onkar Singh, Manmeet Pal Singh, Jasmeet Kaur, Ravi Chand Singh, Sensors and Actuators B 195 (2014) 409–415.

11.   “A novel nanoporous Pd–graphene hybrid synthesized by a facile and rapid process for hydrogen detection”, Duy-Thach Phan, Gwiy-Sang Chung, Sensors and Actuators B 210 (2015) 661–668.

12.   “Enhancing NO2 gas sensing performances at room temperature based on reduced graphene oxide-ZnO nanoparticles hybrids”, Sen Liu, Bo Yu, Hao Zhang, Teng Fei, Tong Zhang, Sensors and Actuators B 202 (2014) 272–278.

13.   “Palladium-Decorated Hydrogen-Gas Sensors Using Periodically Aligned Graphene Nanoribbons”, Yusin Pak, Sang-Mook Kim, Huisu Jeong, Chang Goo Kang,Jung Su Park, Hui Song,  Ryeri Lee, NoSoung Myoung, Byoung Hun Lee, Sunae Seo, Jin Tae Kim, and Gun-Young Jung, ACS Appl. Mater. Interfaces 2014, 6, 13293−13298.

14.  “Room temperature hydrogen gas sensing properties of Pt sputtered F-MWCNTs/SnO2    network”, Shivani Dhall, Neena Jaggi, Sensors and Actuators B 210 (2015) 742–747.

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          Asian Journal of Physics                                                                                                     Vol. 25 No 8, 2016 00-00


Direct Synthesis of Calcium Nanospheres as Nanocarriers by Hydrothermal Method


Sneha Ma and Meenakshi Sundaram Nb

aDepartment of Biomedical Engineering, PSG College of Technology,

Coimbatore 641004, Tamil Nadu, India

bDepartment of Physics, Government Arts College (Autonomous), Salem-7, Tamil Nadu, India

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Calcium is an essential mineral for all living organisms especially for cell physiology. It also plays an important role in building stronger and denser bones. In this work, a simple, environmentally friendly method was employed for the preparation of hollow calcium nanospheres under hydrothermal conditions. Kapok fibers were used as templates and the synthesized nanomaterials are promising for applications such as daily dietary calcium intake for osteoporosis patients, drug delivery and other biomedical fields. © Anita Publications. All rights reserved.

Keywords: Calcium, nanospheres, hydrothermal, drug delivery

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