• Y C Ratnakaram

      Articles written in Bulletin of Materials Science

    • Correlation of radiative properties of rare earth ions (Pr3+ and Nd3+) in chlorophosphate glasses—0.1 and 0.5 mol% concentrations

      Y C Ratnakaram A Viswanadha Reddy

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      Optical properties of chlorophosphate glasses of the type 50P2O5–30Na2HPO4–20RCl (R = potassium and lead) activated by 0.1 and 0.5 mol% of Pr3+ and Nd3+ have been investigated. Optical band gaps (𝐸opt) have been reported for 0.1 and 0.5 mol% concentrations of Pr3+ and Nd3+ doped potassium and lead chlorophosphate glasses. Energy levels and optical transitions of Pr3+ and Nd3+ are assigned. Spectroscopic parameters (𝐸1, 𝐸2, 𝐸3, 𝜉4f and 𝛼), spectral intensities (𝑓expt), Judd–Ofelt intensity parameters (𝛺2, 𝛺4 and 𝛺6) and radiative lifetimes (𝜏R) are correlated for 0.1 and 0.5 mol% concentrations of these two ions in potassium and lead chlorophosphate glasses

    • Optical absorption and fluorescence properties of Er3+ in sodium borate glass

      Y C Ratnakaram J Lakshmi R P S Chakradhar

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      Spectroscopic properties of Er3+ ions in sodium borate glass have been studied. The indirect and direct optical band gaps (𝐸opt) and energy level parameters (Racah (𝐸1, 𝐸2 and 𝐸3), spin-orbit (𝜉4f) and configurational interaction (𝛼)) are evaluated. Spectral intensities for various absorption bands of Er3+ doped sodium borate glass are calculated. Using Judd–Ofelt intensity parameters (𝛺2, 𝛺4, 𝛺6), radiative transition probabilities (𝐴), branching ratios (𝛽) and integrated absorption cross sections (𝛴 ) are reported for certain transitions. The radiative lifetimes (𝜏R) for different excited states are estimated. From the fluorescence spectra, the emission cross section (𝜎p) for the transition, ${}^{4}I_{13/2} \rightarrow {}^{4}I_{15/2}$ is reported.

    • Synthesis and analysis of Fe3+, Co2+ and Ni2+ : PEO + PVP blended polymer composite films for multifunctional polymer applications

      K Naveen Kumar M Vasudeva Reddy L Vijayalakshmi Y C Ratnakaram

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      Blended polymer films of polyethylene oxide + polyvinyl pyrrolidone (PEO + PVP) containing transition metal (TM) ions like Fe3+, Co2+ and Ni2+ have been synthesized by a solution casting method. For these films, structural, thermal, magnetic and optical properties have been studied. X-ray diffraction results reveal the semi-crystalline nature of the polymer films. Thermal stability of the host (undoped) polymer film has been investigated from its thermogravimetric–differential thermal analysis profiles. Raman spectral profiles indicate a complex formation trend owing to the addition of TM ions into the host matrix. Co2+, Fe3+ and Ni2+ ions doped polymer films have revealed ferromagnetism based on their vibrating sample magnetometre profiles. However, the host polymer film has exhibited a paramagnetic nature. Further, ionic conductivities have been calculated using an impedance analyser at different temperatures for all the samples. Among these films, a maximum ionic conductivity (𝜎 = 7.5 × 10−6 S cm−1) has been noticed from PEO + PVP : Ni2+ polymer film at 373 K. Emission analysis of Co2+ : PEO + PVP polymer film has exhibited a strong red emission under an UV source and from both PEO + PVP : Fe3+; PEO + PVP: Ni2+, green emissions have commonly been noticed under an UV source. Thus, based on these results, it could be suggested that these TM ions doped PEO + PVP polymer films are found to be potential multifunctional materials for magneto-electric, magneto-optic fields with encouraging electrical, dielectric and optical properties as well as displaying with ferromagnetic nature from the doped films.

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      Posted on October 12, 2020

      Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
      Chemical Sciences 2020

      Prof. Surajit Dhara — School of Physics, University of Hyderabad, Hyderabad
      Physical Sciences 2020

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