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Malleshappa J.,Tumkur University | Nagabhushana H.,Tumkur University | Prasad B.D.,BMS College of Engineering | Sharma S.C.,Dr Hari Singh Gour University | And 2 more authors.
Optik | Year: 2016

CeO2 nanoparticles (NPs) were synthesized by a facile low temperature solution combustion method using citric acid as fuel. The structural and morphological properties of as-formed and calcined products were characterized by PXRD, SEM, TEM, Raman, UV-visible absorption spectroscopy techniques. Further, the NPs were subjected to photoluminescence (PL) and thermoluminescence (TL) studies. PXRD results and Rietveld refinement analysis confirms the formation of single and pure cubic phase in both as-formed and calcined CeO2 NPs. In both the NPs, Raman spectra exhibit the symmetrical stretching mode of Ce-O vibrational unit at 465 cm-1. The PL emission peak appeared with CeO2 upon 237 nm excitation can be assigned to the oxygen related defects. The CIE and CCT coordinates clearly indicates the possible potential application of CeO2 nanophosphor in display devices. TL studies revealed well resolved glow peak at 224 °C along with a small shouldered peak at 131 °C. The glow peak intensity increases linearly with γ-dose which suggest CeO2 sample is suitable candidate for radiation dosimetric applications. The activation energy, order of kinetics and frequency factor was estimated using glow peak shape method. The study successfully demonstrates a facile simple route for the synthesis of multifunctional CeO2 NPs. © 2015 Elsevier GmbH. All rights reserved. Source


Prasanna Kumar J.B.,GFGC Tumkur | Prasanna Kumar J.B.,Sathyabama University | Ramgopal G.,Maharanis Science College | Vidya Y.S.,Lal Bahadur Shastry Government First Grade College | And 6 more authors.
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2015

We report the synthesis of Y2O3: Eu3+ (1-11 mol%) nanoparticles (NPs) with different morphologies via eco-friendly, inexpensive and simple low temperature solution combustion method using Aloe Vera gel as fuel. The formation of different morphologies of Y2O3: Eu3+ NPs were characterized by PXRD, SEM, TEM, HRTEM, UV-Visible and PL techniques. The PXRD data and Rietveld analysis confirms the formation of single phase Y2O3 with cubic crystal structure. The influence of Eu3+ ion concentration on the morphology, UV-Visible absorption, PL emission and photocatalytic activity of Y2O3: Eu3+ nanostructures were investigated. Y2O3: Eu3+ NPs exhibit intense red emission with CIE chromaticity coordinates (0.50, 0.47) and correlated color temperature values at different excitation ranges from 1868 to 2600 K. The control of Eu3+ ion on Y2O3 matrix influences the photocatalytic decolorization of methylene blue (MB) as a model compound was evaluated under UVA light. Enhanced photocatalytic activity of conical shaped Y2O3: Eu3+ (1 mol%) was attributed to dopant concentration, crystallite size, textural properties and capability of reducing the electron-hole pair recombination. The trend of inhibitory effect in the presence of different radical scavengers followed the order SO4 2- > Cl- > C2H5OH > HCO3 - > CO3 2-. These findings show great promise of Y2O3: Eu3+ NPs as a red phosphor in warm white LEDs as well as eco-friendly heterogeneous photocatalysis. © 2015 Elsevier B.V. All rights reserved. Source


Anilkumar M.R.,East-West Center | Nagaswarupa H.P.,East-West Center | Nagabhushana H.,Tumkur University | Sharma S.C.,Dr Hari Singh Gour University | And 5 more authors.
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2015

MgO:Fe3+ (0.1-5 mol%) nanoparticles (NPs) were synthesized via eco-friendly, inexpensive and simple low temperature solution combustion route using Aloe vera gel as fuel. The final products were characterized by SEM, TEM and HRTEM. PXRD data and Rietveld analysis revealed the formation of cubic system. The influence of Fe3+ ion concentration on the structure morphology, UV absorption, PL emission and photocatalytic activity of MgO:Fe3+ NPs were investigated. The yellow emission with CIE chromaticity coordinates (0.44, 0.52) and average correlated color temperature value was found to be 3540 K which corresponds to warm light of NPs. The control of Fe3+ on MgO matrix influences the photocatalytic decolorization of methylene blue (MB) under UV light. The enhanced photocatalytic activity of MgO:Fe3+ (4 mol%) was attributed to dopant concentration, effective crystallite size, textural properties, decreased band gap and capability for reducing the electron-hole pair recombination. Further, the trends of inhibitory effect in the presence of different radical scavengers were explored. These findings open up new avenues for the exploration of Fe-doped MgO in eco-friendly water applications and in the process of display devices. © 2015 Elsevier B.V. All rights reserved. Source


Prasanna Kumar J.B.,GFGC Tumkur | Prasanna Kumar J.B.,Sathyabama University | Ramgopal G.,Maharanis Science College | Vidya Y.S.,Lal Bahadur Shastry Government First Grade College | And 7 more authors.
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2015

Facile and green route was employed for the synthesis of Y2O3:Dy3+ (1-11 mol%) nanostructures (NSs) using Aloe vera gel as fuel. The formation of different morphologies of Y2O3:Dy3+ NSs were characterized by SEM, TEM and HRTEM. PXRD data and Rietveld analysis evident the formation of single phase Y2O3 with cubic crystal structure. The influence of Dy3+ ion concentration on the structure morphology, UV absorption, PL emission and photocatalytic activity of NSs were investigated. NSs exhibited an intense warm white emission with CIE chromaticity coordinates (0.32, 0.33) and average CCT value ∼5525 K which corresponds to vertical day light. The control of Dy3+ ion on Y2O3 matrix influences the photocatalytic decolorization of Metanil Yellow as a model compound was evaluated. The enhanced photocatalytic activities of core shell structured Y2O3:Dy3+ (1 mol%) was attributed to co-operation effect of dopant concentration, crystallite size, textural properties and capability for reducing electron-hole pair recombination. Further, the recycling catalytic ability of Y2O3:Dy3+ (1 mol%) nanostructure was also evaluated and found promising photocatalytic performance with negligible decrease in decolorization efficiency even after sixth successive cyclic runs. Considering its green, facile synthesis and recyclable feature from an aqueous solution, the present Y2O3:Dy3+ (1 mol%) nanophosphor can be considered as one of the ideal photocatalyst for various potential applications. © 2015 Elsevier B.V. All rights reserved. Source


Gurushantha K.,East-West Center | Anantharaju K.S.,East-West Center | Nagabhushana H.,Tumkur University | Sharma S.C.,Chhattisgarh Swami Vivekananda Technical University | And 5 more authors.
Journal of Molecular Catalysis A: Chemical | Year: 2014

Cubic ZrO2: Fe3+ (0.5-4 mol%) nanoparticles (NPs) were synthesized via bio-inspired, inexpensive and simple route using Phyllanthus acidus as fuel. PXRD, SEM, TEM, FTIR, UV absorption and PL studies were performed to ascertain the formation of NPs. Rietveld analysis confirmed the formation of cubic structure. The influence of Fe3+ on the structure, morphology, UV absorption, PL emission and photocatalytic activity of NPs were investigated. The CIE chromaticity coordinates (0.36, 0.41) show that NPs could be a promising candidate for white LEDs. The influence of Fe3+ on ZrO2 matrix for photocatalytic degradation of AO7 was evaluated under UVA and Sunlight irradiation. The enhanced photocatalytic activity of spherical shaped ZrO2: Fe3+ (2 mol%) under UVA light was attributed to dopant concentration, crystallite size, narrow band gap, textural properties and capability for reducing the electron-hole pair recombination. The trend of inhibitory effect in the presence of different radical scavengers were followed the order SO4 2- > Cl- > C2H5OH > HCO3 - > CO3 2-. The recycling catalytic ability of the ZrO2: Fe3+ (2 mol%) was also evaluated with a negligible decrease in the degradation efficiency even after the sixth successive run. © 2014 Elsevier B.V. All rights reserved. Source

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