• S J DHOBLE

      Articles written in Bulletin of Materials Science

    • Synthesis and characterization of Eu3+ activated hexagonal ABaGd(PO4)2 (A+=Li, Na, or K) phosphates

      A M Band S J Dhoble R B Pode

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      BaGd0·5(PO4)2: Eu0·53+ and ABaGd0·5(PO4)2: Eu0·53+ (where A+=Li, Na or K) double phosphates were synthesized by solid state diffusion method. These powders were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. XRD results showed many distinct lines in the XRD spectra. SEM measurement showed grains of different sizes in double phosphates. The Eu3+-ion emission lines for5D07Fj (j=1, 2, 3, and 4) transitions showed a splitting into 3, 2, 1, and 2 components, respectively. Strength of these lines was enhanced by the addition of alkali ion to BaGd0·5(PO4)2: Eu0·53+ double phosphate. However, as the alkali ion varied from Li+ to K+, the intensity of5D07F2 line (617 nm) in the red region increased at the cost of5D07F1 line (599 nm) in the orange region. Suitable explanation has been proposed for this phenomena.

    • Optical properties of rare earth-activated Ca$_3$(PO$_4$)$_2$:RE (RE = Eu$^{3+}$ and Dy$^{3+}$) phosphors prepared by wet chemical synthesis

      S K RAMTEKE A N YERPUDE N S KOKODE S J DHOBLE

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      Optical properties of rare earth-activated Ca$_3$(PO$_4$)$_2$:RE (RE = Eu$^{3+}$ and Dy$^{3+}$) phosphors obtained by wet chemical synthesis method, are reported in this paper. The phase confirmation of synthesized phosphor host is done by X-ray diffraction study. SEM images of the sample host reveal irregular morphology with collection of particles and porous nature. The crystal structure is not viewed with naked eyes, although particle size ranges from 2–5 micrometres. Photoluminescence characterization of Ca$_3$(PO$_4$)$_2$:Eu$^{3+}$ gives characteristic orange–red emission at wavelengths of 594, 613 and 617 nm upon near UV excitation at 397 nm attributed to ${}5$D$_0$ ${\rightarrow}$ ${}7$F$_1$, ${}7$F$_2$ transition of rare earth Eu$^{3+}$ ion. Whereas Ca$_3$(PO$_4$)$_2$:Dy$^{3+}$ gives blue–yellow emissions at wavelengths 483 and 574 nm due to near UV excitation at wavelength of 351 nm, which are corresponding to ${}4$F$_{9/2}$ ${\rightarrow}$ ${}6$H$_{15/2}$, ${}6$H$_{13/2}$ transitions of dopant ion Dy$^{3+}$. Colour coordinates from CIE diagram of 483 and 574 nm are obtained at (x = 0.0781, y = 0.1704) and (x = 0.471, y = 0.527) for the Ca$_3$(PO$_4$)$_2$:Dy$^{3+}$ phosphor. Whereas in the case of Ca$_3$(PO$_4$)$_2$:Eu$^{3+}$ for an emission wavelength of 613 nm, the colour coordinates are found to be (x = 0.674, y = 0.325). The presented optical investigation of phosphor displays that the reported phosphor can be a potential contender for ecofriendly solid-state lighting.

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    • Dr Shanti Swarup Bhatnagar for Science and Technology

      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
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      Posted on July 25, 2019

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