Sri Venkateswara Degree College

Cuddapah, India

Sri Venkateswara Degree College

Cuddapah, India

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Ravindra Reddy T.,Sri Venkateswara Degree College | Lakshmi Reddy S.,Sri Venkateswara Degree College | Endo T.,Mie University
Radiation Effects and Defects in Solids | Year: 2016

A light-yellow-colored pyrophyllite (Al2O3·SiO2) mineral obtained from Vempalli, Cuddapah district, Andhra Pradesh, India, is investigated in the present work. Chemical analysis carried out using energy-dispersive spectroscopy (EDX) shows that Fe2O3 is present by about 1.56 wt%. Structural characterization was performed using X-ray diffraction (XRD). XRD results suggest that the unit cell is monoclinic with a = 5.16, b = 8.798, c = 9.347 Å and β = 100.46°. The ligands around the metal ion present in the structure are investigated using FTIR spectroscopy. EDX analysis indicates that iron and titanium are only two transition metals present in it. Morphology studied using scanning electron microscopy suggests that the unit cell consists of a dioctahedral layered structure. Fe3+ is present in the location of Al3+ in the unit cell of pyrophyllite. Electron paramagnetic resonance results indicate that the unit cell of the crystal contains Fe(III), and its g values are found to be 4.10 and 2.0. Infrared properties are due to the presence of silicate and hydroxyl anions as ligands. Nonlinear optical measurements carried out using Z-scan reveal the occurrence of strong nonlinear optical limiting in the material, indicating potential applications in laser safety devices. © 2016 Informa UK Limited, trading as Taylor & Francis Group


Madhukar Reddy C.,Sri Venkateswara University | Sudhakar Reddy B.,Sri Venkateswara Degree College | Dillip G.R.,Sri Venkateswara University | Mallikarjuna K.,Sri Venkateswara University | Deva Prasad Raju B.,Sri Venkateswara University
Journal of Molecular Structure | Year: 2012

This study reports on the concentration dependent fluorescence properties of Tb3+-doped lead containing calcium zinc sodium fluoroborate (LCZSFB) glasses and are analyzed by DSC, FT-IR, FT-Raman, optical absorption, emission and decay curve spectra. Co-existence of trigonal BO3 and tetrahedral BO4 units was evidenced by FT-IR and Raman spectroscopy. Judd-Ofelt theory was applied to the experimental oscillator strengths to evaluate the J-O intensity parameters. The fluorescence spectra of Tb 3+-doped glasses have revealed prominent blue and green emissions originating from 5D3 and 5D4 excited levels to 7FJ ground state multiplet, respectively. The luminescent intensity of the transitions originating from 5D 4 state increases with increase of Tb3+ concentration and no quenching effect is noticed up to 2 mol% of Tb3+ ions. Chromaticity color coordinates have been calculated and the dominant emission in the green region is discussed. The nature of decay curves of 5D 4 level for different Tb3+ ion concentration in all LCZSFB glasses has been analyzed. Using the J-O intensity parameters as well as from the emission and decay curve measurements, various radiative and fluorescence properties have been calculated for the 5D4 fluorescent level. Based on these results, the utility of Tb3+ ions doped LCZSFB glasses as laser active materials for high intensity emissions in the green region is discussed. © 2012 Elsevier B.V. All rights reserved.


Ravi O.,Sri Venkateswara University | Reddy C.M.,Sri Venkateswara University | Reddy B.S.,Sri Venkateswara Degree College | Raju B.D.P.,Sri Venkateswara University
Optics Communications | Year: 2014

Niobium containing tellurium calcium zinc borate (TCZNB) glasses doped with different concentrations of Dy3+ ions were prepared by the melt quenching method and their optical properties have been studied. The Judd-Ofelt (J-O) intensity parameters Ωt (t=2, 4 and 6) were calculated using the least square fit method. Based on the magnitude of Ω2 parameter the hypersensitivity of 6H15/2→ 6F11/2 has also been discussed. From the evaluated J-O intensity parameters as well as from the emission and lifetime measurements, radiative transition properties such as radiative transition probability rates and branching ratios were calculated for 4F9/2 excited level. It is found that for Dy3+ ion, the transition 4F9/2→6H13/2 shows highest emission cross-section at 1.0 mol% TCZNB glass matrix. From the visible luminescence spectra, yellow to blue (Y/B) intensity ratios and chromaticity color coordinates were also estimated. The TCZNB glasses exhibit good luminescence properties and are suitable for generation of white light. © 2013 Elsevier B.V. All rights reserved.


Nageswara Raju C.,Sri Venkateswara Degree College | Adinarayana Reddy C.,Sri Venkateswara Degree College | Sailaja S.,Sri Venkateswara Degree College | Seo H.J.,Pukyong National University | Sudhakar Reddy B.,Sri Venkateswara Degree College
Luminescence | Year: 2012

This article reports on the optical properties of Er 3+ ions doped CdO-Bi 2O 3-B 2O 3 (CdBiB) glasses. The materials were characterized by optical absorption and emission spectra. By using Judd-Ofelt theory, the intensity parameters ω λ (λ = 2, 4, 6) and also oscillatory strengths were calculated from the absorption spectra. The results were used to compute the radiative properties of Er 3+:CdBiB glasses. The concentration quenching and energy transfer from Yb 3+-Er 3+ were explained. The stimulated emission cross-section, full width at half maximum (FWHM) and FWHM × σpE values are also calculated for all the Er 3+:CdBiB glasses. Copyright © 2011 John Wiley & Sons, Ltd.


Sudhakar Reddy B.,Gwangju Institute of Science and Technology | Hwang H.-Y.,Gwangju Institute of Science and Technology | Jho Y.-D.,Gwangju Institute of Science and Technology | Seung Ham B.,Gwangju Institute of Science and Technology | And 4 more authors.
Ceramics International | Year: 2015

The optical properties of borotellurite glasses doped with Nd3+ ions or codoped with Er3+-Yb3+ ions are investigated, in order to evaluate the potential application of these types of glass in laser systems and amplifier materials. The Judd-Ofelt (JO) model is used to determine the absorption intensities of both types of glass so as to establish the J-O intensity parameters (Ωλ). The J-O intensity parameters are then used to determine the various radiative parameters viz., the radiative transition probabilities (AR), branching ratios (βR), stimulated emission cross-sections (σe), full width half maxima (Δλp) and radiative lifetimes (τR) of both types of glass, which are also compared to the equivalent parameters for other host glasses. It has been shown that Yb3+ acts as an Er3+ sensitizer and contributes largely to the improvement of the spectroscopic properties of the glasses that is codoped with Er3+-Yb3+. The obtained values ofAR, βR, τR, σe and Δλp for the Nd3+- and Er3+-doped glass show that both the 4F3/2→4I11/2 transition at 1.06 μm in the Nd3+ case and the 4I13/2→4I15/2 transition at 1.56 μm for the Er3+ case exhibit better NIR luminescence at a level suitable for photonic device applications. The potential of the glasses examined in this study, due to their promising gain media, is also discussed in terms of the development of solid state NIR lasers and optical amplification for telecommunication applications. © 2014 Elsevier Ltd and Techna Group S.r.l.


Sailaja S.,Sri Venkateswara Degree College | Nageswara Raju C.,Sri Venkateswara Degree College | Adinarayana Reddy C.,Sri Venkateswara Degree College | Deva Prasad Raju B.,Sri Venkateswara University | And 2 more authors.
Journal of Molecular Structure | Year: 2013

This article reports on the optical properties of cadmium bismuth borate (CdBiB) glasses doped with various concentrations of Sm3+ ions. FT-IR spectra of Sm3+:CdBiB glasses have been used to identify the functional groups present in the composition of the glasses. The emission spectra of Sm3+:CdBiB glasses have shown an intense reddish-orange emission at 600 nm (4G5/2 → 6H 7/2). From the absorption spectrum, the experimental oscillator strengths were determined and have been used to calculate the Judd-Ofelt (J-O) intensity parameters. By using the J-O intensity parameters, various radiative properties have been studied and computed for the various transitions of Sm 3+:CdBiB glasses. Based on the values of stimulated emission cross section, radiative transition rate and the branching ratio of the emission transition 4G5/2 → 6H7/2, it is suggested that 1.0 mol% of Sm3+:CdBiB glass is the promising luminescent material towards lasing applications. The nature of luminescence decay curves of 4G5/2 level with different concentrations of Sm3+:CdBiB glasses are also reported. © 2013 Elsevier B.V. All rights reserved.


Madhukar Reddy C.,Sri Venkateswara University | Dillip G.R.,Sri Venkateswara University | Mallikarjuna K.,Sri Venkateswara University | Zulifiqar Ali Ahamed S.,Sri Venkateswara University | And 2 more authors.
Journal of Luminescence | Year: 2011

Lead containing calcium zinc sodium fluoroborate glasses (LCZSFB) with molar composition of 20PbO5CaO5ZnO10NaF(60-x) B2O3x Sm2O3, (x=0.1, 0.25, 0.5, 1.0 and 2.0 mol%) were prepared and investigated by the XRD, FTIR, optical absorption, photoluminescence and decay curve analysis. JuddOfelt theory was applied to the experimental oscillator strengths to evaluate the phenomenological JO intensity parameters Ωλ (λ=2, 4 and 6). Using the JO intensity parameters as well as from the emission and decay measurements, various radiative parameters such as transition probabilities (AR), radiative lifetimes (τR), measured lifetimes (τm), calculated branching ratios (βR), measured branching ratios (βm), effective bandwidth (Δλeff) and stimulated emission cross sections σ(λp) have been calculated for the excited 4G5/2 luminescent level. The nature of decay curves of 4G5/2 level for different Sm3 ion concentrations in all LCZSFB glasses has been analyzed and the lifetimes are noticed to decrease with increase of concentration. The concentration quenching has been attributed to the energy transfer through the cross-relaxation between Sm3 ions. Based on these results, the utility of Sm3 ions doped lead containing fluoroborate glasses as laser active materials in the visible region is discussed. © 2011 Elsevier B.V. All rights reserved.


Reddy B.S.,Gwangju Institute of Science and Technology | Reddy B.S.,Sri Venkateswara Degree College | Kadukar M.R.,Rashtrasant Tukadoji Maharaj Nagpur University | Hwang H.-Y.,Gwangju Institute of Science and Technology | And 5 more authors.
Physica B: Condensed Matter | Year: 2015

A series of Eu3+, Sm3+, and Dy3+ ion doped magnesium yttrium silicate [MgY4Si3O13] phosphors was synthesized using the solid-state reaction method with a grain size of approximately 500 nm in hexagonal symmetry. The photoluminescence (PL) spectra of the Eu3+, Sm3+, and Dy3+:MgY4Si3O13 phosphors exhibit bright red, orange-red and yellow emissions at 615 nm (5D0→7F2), 603 nm (4G52→6H7/2), and 574 nm (4F9/2→6H13/2), respectively. The thermoluminescence (TL) of the phosphors displays the maximum intensity consistently at 10 mol% of the ion concentrations, with a single glow peak around 165 C (Eu3+-activated phosphor), 230 C (Sm3+-activated phosphor), and 230 C (Dy3+-activated phosphor), respectively. The trap parameters such as the order of kinetics (b), activation energy (E), frequency factor (S), and Balarin parameter (γ) associated with the most intensive glow peak of these phosphors were finally determined by analyzing their line-shapes on the basis of Chen's method. © 2015 Elsevier B.V. All rights reserved.


Raju C.N.,Sri Venkateswara Degree College | Reddy C.A.,Sri Venkateswara Degree College | Sailaja S.,Sri Venkateswara Degree College | Seo H.J.,Pukyong National University | Reddy B.S.,Sri Venkateswara Degree College
Journal of Materials Science | Year: 2012

This article reports on the optical absorption and NIR emission properties of Nd 3+ ions doped CdO-Bi 2O 3-B 2O 3 (CdBiB) glasses. Judd-Ofelt theory has been applied to calculate the oscillatory strengths of the transitions in the absorption spectra and also the intensity parameters Ω λ (λ = 2, 4, and 6). These results were then used to compute the radiative properties of emission transitions of Nd 3+:CdBiB glasses. From the NIR emission spectra of Nd 3+:CdBiB glasses, three NIR emission bands are observed at 900, 1069, and 1338 nm and assigned to the transitions ( 4F 3/2 → 4I 9/2), ( 4F 3/2 → 4I 11/2), and ( 4F 3/2 → 4I 13/2), respectively. The concentration quenching phenomenon has also been explained. The stimulated emission cross-section and FWHM values were calculated for all the Nd 3+:CdBiB glasses. © 2011 Springer Science+Business Media, LLC.


PubMed | P.A. College, Rashtrasant Tukadoji Maharaj Nagpur University and Sri Venkateswara Degree College
Type: | Journal: Luminescence : the journal of biological and chemical luminescence | Year: 2016

This article reports on the luminescence properties of rare earth (Dy

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