2015-16

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BM FO-PVDF elect rospun fiber based t unable met amat erial st ruct ures for elect romagnet ic int erference shielding in microwave frequency region
(2016-01-07T11:17:17Z) Revathi, Venkatachalam; Dinesh Kumar, Sakthivel; Subramanian, Venkatachalam; Chellamuthu, Muthamizhchelvan
Met amat erial st ruct ures are art ificial st ruct ures t hat are useful in controlling t he flow of elect romagnet ic radiat ion. In t his paper, composit e fibers of sub-micron t hickness of barium subst it ut ed magnesium ferrit e (Ba0.2Mg0.8 Fe2O4 ) – polyvinylidene fluoride obt ained by elect rospinning is used as a subst rat e t o design elect romagnet ic int erference shielding st ruct ures. While elect rospinning improves t he ferroelect ric propert ies of t he polyvinylidene fluoride, t he presence of barium magnesium ferrit e modifies t he magnet ic property of t he composit e fiber. T he dielect ric and magnet ic propert ies at microwave frequency measured using microwave cavity pert urbat ion t echnique are used t o design t he reflect ion as well as absorpt ion based t unable met amat erial st ruct ures for elect romagnet ic int erference shielding in microwave frequency region. For one of t he st ruct ures, t he simulat ion indicat es t hat single negat ive met amat erial st ruct ure becomes a double negat ive met amat erial under t he ext ernal magnet ic field.
Facile combustion synthesized orthorhombic GdAlO3:Eu3+ nanophosphors: Structural and photoluminescence properties for WLEDs
(2015-08-13T05:07:28Z) Jisha, P K; Ramachandra, Naik; Prashantha, S.C.; Nagabhushanad, H.; S.C. Sharmae, B.; Premkumarg, H.B; Nagaswarupac, H.P.; Anantharajuc, K.S.; Prasadf, Daruka
Nanoparticles of Eu3+ doped (1–11 mol%) GdAlO3 were prepared using low temperature (350 °C) solution combustion technique with gadalonium nitrate as oxidizer and oxalyl di-hydrazide (ODH) as a fuel. The synthesized samples were calcined at 1000 °C for 3 h and used for Powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and UV–visible absorption (UV–vis) characterization techniques. A pure orthorhombic was obtained in calcined samples. The average crystallite sizes were estimated using Scherrer's formula, W–H and size–strain plots and found to be in the range 25–50 nm and the same was confirmed by Transmission electron microscopy (TEM) studies. The phosphors exhibit bright red emission upon 395 nm excitation. The characteristic emission peaks recorded at ~591, 612, 654 and 694 nm (5D0→7Fj=1,2,3,4) were attributed to the 4f–4f intra-shell transitions of Eu3+ ions. The CIE chromaticity co-ordinates were calculated from emission spectra, the values (x, y) were very close to NTSC standard value of red emission. Further, the average CCT value was found to be ~2369 K, as a result the prepared nanophosphor was highly useful for red component of white light emitting devices and also for solid state display applications.
Judd Ofelt ANALYSIS OF Eu3+ DOPED Mg2S104 NANOPHOSPHORS
(2016-03-01T07:16:53Z) Ramachandra, Naik; Prashantha, S C; Nagabhushana, H; Sharma, S C; Nagaswarupa, HP
A note on mathematical programming problems
(2016-01-07T11:11:56Z) Rashi, Khubnani; Tarunika, Sharma
A review has been done on the growth and improvement of solution of non linear programming problems under various factors. The mathematical work of Kuhn-Tucker, Fritz John, Mangasarian, Wolfe, Vond, Kanniappan has been traced and compared.
Penetrative Marangoni Convection in Fluid Layer with Soret Effect
(2016-01-07T11:08:13Z) Gangadharaiah, Y. H
The effects of internal heat source and Soret effect under zero gravity in a fluid layer is studied. The bottom boundary of the fluid layer is assumed to be either conducting or insulating to temperature and solute concentration perturbations while the top boundary is free and insulating. The linear stability analysis is followed and an exact solution is obtained for the corresponding eigen value problem by assuming that stationary convection is exhibited at the neutral state. The Soret parameter and the presence of volumetric internal heat source in a fluid layer play a decisive role on the stability characteristics of the system. It is observed that both stabilizing and destabilizing factors can be enhanced due to the simultaneous presence of a volumetric source and Soret effect so that a more precise control (suppress or augment) of Marangoni instability in a binary fluid mixture of fluid layer is possible.
Photoluminescence and JuddeOfelt analysis of Eu3þ doped LaAlO3 nanophosphors for WLEDs
(2016-01-07T11:33:50Z) Manohar, T; Naik, Ramachandra; Prashantha, SC; Nagabhushana, H; Sharma, SC; Nagaswarupa, HP
Europium doped lanthanum aluminate nanophosphors were synthesized by a combustion process using Oxalyl di-hydrazide as fuel. The nanophosphors calcined at 900 C for 3 h were characterized by PXRD, FTIR spectroscopy, SEM and TEM. The average crystallite size determined by TEM and Scherrer's method was found to be in the range 20e50 nm. The characteristic emission peaks (lexi - 395 nm) recorded at ~ 591, 616, 646 and 696 nm (5D0/7Fj¼0,1,2,3) may be attributed to the 4fe4f intra shell transitions of Eu3þ ions. The estimated CIE chromaticity co-ordinates were calculated from emission spectra, were close to the national television standard committee value of red emission. Correlated color temperature was found to be 1929 K.
Photoluminese Properties of Eu34 and Dy34 Doped GdAIO3
(2016-03-01T07:22:19Z) Jisha, PK; Ramachandra, Naik; Prashanth, SC; Nagaswarupa, HP
Relaxor-like ferroelectric behaviour favoured by short-range B-site ordering in 10% Ba2+ substituted MgFe2O4
(2016-01-07T11:35:59Z) Chithra, Lekha; Ramesh; Revathi, V; Subramanian, V
Using the molten salt method, pristine and Ba2+ substituted MgFe2O4 are prepared. The relaxor-like behaviour observed in the dielectric dispersion indicates the existence of B-site short-range ordering with the local P4122/P4322 symmetry which is confirmed by the Raman spectroscopy. The paper further analyses the origin of polarization using Maxwell–Wagner fit and Nyquist plot. This work suggests a possible way to increase the relaxor-like ferroelectric ordering, larger span of relaxation temperature (DTm) and the effective masking of electronic contribution by the substitution of Ba2+ ion.
A single phase, red emissive Mg2SiO4:Sm3+ nanophosphor prepared via rapid propellant combustion route
(2015-05-05T07:14:12Z) Ramachandra, Naik; Prashantha, S C; Nagabhushana, H
Mg2SiO4:Sm3+ (1–11 mol%) nanoparticles were prepared by a rapid low temperature solution combustion route. The powder X-ray diffraction (PXRD) patterns exhibit orthorhombic structure with a-phase. The average crystallite size estimated using Scherer’s method, W–H plot and strain–size plots were found to be in the range 25–50 nm and the same was confirmed by Transmission Electron Microscopy (TEM). Scanning electron microscopy (SEM) pictures show porous structure and crystallites were agglomerated. The effect of Sm3+ cations on luminescence of Mg2SiO4 was well studied. Interestingly the samples could be effectively excited with 315 nm and emitted light in the red region, which was suitable for the demands of high efficiency WLEDs. The emission spectra consists of four main peaks which can be assigned to the intra 4-f orbital transitions of Sm3+ ions 4G5/2?6H5/2 (576 nm), 4G5/2?6H7/2(611 nm), 4G5/2?6H9/2 (656 nm) and 4G5/2?6H11/2 (713 nm). The optimal luminescence intensity was obtained for 5 mol% Sm3+ ions. The CIE (Commission International de I’Eclairage) chromaticity co-ordinateswere calculated from emission spectra, the values (0.588, 0.386) were close to the NTSC (NationalTelevision Standard Committee) standard value of red emission. Coordinated color temperature (CCT)was found to be 1756 K. Therefore optimized Mg2SiO4:Sm3+ (5 mol%) phosphor was quite useful for solid state lighting.
Some New Properties on Topological Spaces
(2016-01-07T11:20:54Z) Raj, Vijilius Helena; Missier, Pious
In this journey, we are going to explore the “separation axioms” in greater detail. Separation axioms are one among the most common, important and interesting concepts in Topology. They can be used to define more restricted classes of topological spaces. We shall try to understand how these axioms are affected on subspaces, taking products, and looking at small open neighborhoods.
Spectroscopic and photoluminescence properties of MgO:Cr3+ nanosheets for WLEDs
(2016-01-07T11:25:23Z) Devaraja, P.B.; Nagabhushana, H; Sharma, S C; Naik, Ramachandra; Prashantha, SC; Nagaswarupa, HP; Anantharaju, KS; Premkumar, HB; Jnaneshwara, DM
This work explores the synthesis of nanocrystalline MgO:Cr3+ (1–9 mol%) nanophosphors via solution combustion route at 400 C. The nanophosphors were well characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infra-Red (FTIR) spectroscopy. PXRD results confirm cubic phase and SEM micrographs indicate that the particles are highly porous and agglomerated. The TEM images show that the powder consists of spherical particles of size 5–15 nm. Upon 356 nm excitation the emission profile of MgO:Cr3+ exhibits an emission peak at 677 nm due to 2Eg?4A2g transition. It was observed that PL intensity increases with increase in Cr3+ concentration and highest PL intensity was observed for 3 mol% doped sample and afterward it decreases, attributed to concentration quenching. The resultant CIE chromaticity co-ordinates in the white region make the present phosphor highly useful for display applications and also for white light-emitting diodes (WLEDs).
Synthesis and Structural studies of Barium Substitute Mangnesium ferrite-polyvinylidene fluoride composite fibers
(2016-03-01T07:26:54Z) Revathi, V; Subramanian, V; Muthamizhechelvan, C
Synthesis of Solution Combustion Based Nanosized Cr2O, Doped Polymer Nanocomposites and Their Characterization
(2016-03-01T07:11:29Z) Prashanth, KS; Mahesh, SS; Nanda, Prakash M B; Somashekar, RS; Nagabhushana, B M
Solution combustion based nanosized Chromium Oxide nanoparticles blended pVikitiaCI:er203 nanocomposite thin films of 2 wt%, 4 wt%. 6 wt' -1 and S: were synthesized using solvent cast method. The chromium nitrate CrtN001-61-1:0 was used as the precursor and oxalyl dihydrazide (C.11-1,N40,1 OD11 as oxidizer. The Chromium oxide nanoparticles were characterized using XRD. The XRD confirms the cnstal structure of the synthesized nanoparticles and the formation of nanocomposites The morphology of the ensuing nanoparticles and nanocomposites were characterized by SEMI. The FTIR and SENI results are in confirmation with XRD results indicating the formation of nanocomposites The objective of the study was to prepare water soluble polymer nanocomposites which may have potential polymer nanotechnologieal applications.
Zn2TiO4:Eu3+ nanophosphor: Self explosive route and its near UV excited photoluminescence properties for WLEDs
(2016-01-07T11:29:10Z) Girish, KM; Naik, Ramachandra; Prashantha, SC; Nagabhushana, H; Nagaswarupa, HP; Anantha Raju, KS; Premkumar, HB; Sharma, SB; Nagabhushana, BM
A simple and low-cost solution combustion method was used to prepare Eu3+ (1–11 mol%) doped Zn2TiO4 nanophosphors at 500 C using zinc nitrates as precursors and oxalyl di-hydrazide (ODH) as fuel. The final product was calcined at 1100 C for 3 h and then characterized by powder X-ray diffraction (PXRD), fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV–visible absorption (UV–Vis). The PXRD patterns of the sample calcined at 1100 C show pure cubic phase. The crystallite size was estimated using Scherrer’s method and found to be in the range 20–25 nm and the same was confirmed by TEM studies. Effects of Eu3+ (1–11 mol%) cations on the luminescence properties of Zn2TiO4 nanoparticles were studied. The samples exhibit intense red emission upon 395 nm near ultra violet (NUV) excitation. The characteristic emission peaks recorded at 578, 592, 613 and 654 nm may be attributed to the 4f–4f intra shell transitions (5D0?7Fj=0,1,2,3) of Eu3+ cations. The CIE chromaticity co-ordinates and CCT were calculated from emission spectra and the values (x, y) were very close to NTSC standard values for red emission and CCT was close to Plankian locus. Therefore, the present phosphor may be highly useful for display applications.

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