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Author: search.filters.author.Basavapoornima, ChSubject: search.filters.subject.Eu3+ ion

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    Structural, optical, luminescence spectroscopy and radiation shielding properties of Eu3+:borophosphotellurite glasses
    (2024-10-01)
    Masthanaiah, E.
    ;
    Basavapoornima, Ch
    ;
    Lokanadham, R.
    ;
    Pecharapa, Wisanu
    ;
    Kaewkhao, J.
    Recently much effort is being paid to study the rare earth ions in multi component glass formers as they exhibit high enhancement in the efficiency of luminescence properties. In this direction, the present study focuses on the preparation and analysis of novel glass batches with composition of (in mol %) BPTCZEu: 40B<inf>2</inf>O<inf>3</inf>+20P<inf>2</inf>O<inf>5</inf>+15TeO<inf>2</inf>+ 10CaO+(15−x)ZnO + xEu<inf>2</inf>O<inf>3</inf>, x = 0.1, 0.5, 1.0, 1.5, 2.0 and 2.5. The important spectroscopic techniques such as optical absorption, luminescence, excitation and decay curves are taken to analyse the BPTCZEu glasses. Luminescence spectrum of BPTCZEu comprise of emission from excited (<sup>5</sup>D<inf>0</inf>) to the lower multiplets (<sup>7</sup>F<inf>J</inf> (J = 0−4)), among these, <sup>5</sup>D<inf>0</inf> → <sup>7</sup>F<inf>2</inf> (red luminescence) at 612 nm found to be very intense. Judd−Ofelt characteristics, Ω<inf>2</inf>, Ω<inf>4</inf> and Ω<inf>6</inf>, were derived from different constraints. To know the site symmetry around Eu<sup>3+</sup>, the fluorescence intensity ratio of <sup>5</sup>D<inf>0</inf> → <sup>7</sup>F<inf>2</inf> vs. <sup>5</sup>D<inf>0</inf> → <sup>7</sup>F<inf>1</inf> were analysed. Exciting <sup>7</sup>F<inf>0</inf> → <sup>5</sup>L<inf>6</inf> and monitoring <sup>5</sup>D<inf>0</inf> → <sup>7</sup>F<inf>2</inf>, the lifetime of <sup>5</sup>D<inf>0</inf> level is determined to be 2 ms which is independent of Eu<sup>3+</sup> content. The colour coordinates for all the Eu<sup>3+</sup> concentrations are estimated to fall in the reddish−orange region. Theoretical radiation shielding results showed that substituting Eu<inf>2</inf>O<inf>3</inf> for ZnO in the glasses lowers photon number that can pass via the material, enhancing the glass system's trend to shield high energy radiation. These stimulated results are compared with experimental measurements of mass attenuation coefficient with respect to energy up to 662 KeV using Cs−137 source. All these findings obtained from title glasses are compared and discussed with respect to reported Eu<sup>3+</sup>:glasses and no systematic variation has been noticed either with single, bi− or multi−component glass formers and therefore needs further systematic work to relate Eu−radiation−ligand interaction.
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    Item type:Publication,
    Spectroscopic investigation and local structure of Eu3+ ions in lead phosphate glasses for optical device applications
    (2024-04-01)
    Basavapoornima, Ch
    ;
    Masthanaiah, E.
    ;
    Vijaya, N.
    ;
    Depuru, Shobha Rani
    ;
    Kaewkhao, J.
    Phosphate-based glasses are promising materials which are being employed for broad range of applications whereas Eu<sup>3+</sup> is an efficient activator due to its predominant <sup>5</sup>D<inf>0</inf> →<sup>7</sup>F<inf>2</inf> emission (red region). In this direction, an attempt has been made to investigate the effect of Eu<sup>3+</sup> ions doped lead phosphate glasses (PPbKANEu: P<inf>2</inf>O<inf>5</inf>+PbO+K<inf>2</inf>O+Al<inf>2</inf>O<inf>3</inf>+Na<inf>2</inf>O+Eu<inf>2</inf>O<inf>3</inf>) to explore possible photonic device applications. Optical absorption, excitation, photoluminescence and decay rates are used to characterize the PPbKANEu glasses. The photoluminescence spectrum of Eu<sup>3+</sup>:PPbKAN glasses exhibit emission channels from the first excited (<sup>5</sup>D<inf>0</inf>) to the ground (<sup>7</sup>F<inf>J</inf> (J =0–4)) multiplets. To determine the local site symmetry of surrounding Eu<sup>3+</sup> ions, the relative fluorescence intensity ratio of <sup>5</sup>D<inf>0</inf>→<sup>7</sup>F<inf>1</inf> versus <sup>5</sup>D<inf>0</inf>→<sup>7</sup>F<inf>2</inf> emission channels has been analyzed. The emission spectrum of PPbKANEu glasses exhibits a comprehensive lifting of degeneracy of <sup>5</sup>D<inf>0</inf>→<sup>7</sup>F<inf>2</inf> and <sup>5</sup>D<inf>0</inf>→<sup>7</sup>F<inf>1</inf> emission channels. By considering C<inf>2v</inf> symmetry for Eu<sup>3+</sup> ions, the second (B<inf>0</inf><sup>2</sup><sup>=</sup> −406 and B<inf>2</inf><sup>2</sup>=−158) and fourth (B<inf>0</inf><sup>4</sup>=980, B<inf>2</inf><sup>4</sup>=297 and B<inf>4</inf><sup>4</sup>=926 cm<sup>–1</sup>) rank crystal–field (CF) characteristics were estimated along with CF strength factor (S= 402 cm<sup>–1</sup>). The lifetime of <sup>5</sup>D<inf>0</inf> state is estimated to be 2.09, 2.23, 2.21 and 2.21 ms for 0.1, 0.5, 1.0 and 2.0 mol% of Eu<sup>3+</sup> ions, respectively. The analysis of the decay times reveals that the lifetime of <sup>5</sup>D<inf>0</inf> state is less affected by the concentration of the Eu<sup>3+</sup> ion. The results are compared and discussed with reported values and confirm the potentiality of the PPbKANEu glasses for optical device applications in visible regions.