Swift heavy ion induced structural, iono and photoluminescence properties of β-CaSiO 3:Dy 3+ nanophosphor
CaSiO(3):Dy(3+) (1-5 mol%) nanophosphors have been prepared by a low temperature solution combustion method. The structural and luminescence (ionoluminescence; IL and photoluminescence; PL) studies have been carried out for pristine and ion irradiated samples. The XRD patterns of pristine sample show a prominent peak at (320) for the monoclinic structure of β-CaSiO(3). Upon ion irradiation, the intensity of the prominent peak is decreased at the fluence of 7.81 × 10(12)ions cm(-2) and at higher fluence of 15.62 × 10(12)ions cm(-2), the prominent peak completely vanishes. The decrease in peak intensity might be due to the stress induced point defects. On-line IL and in situ PL studies have been carried out on pelletized samples bombarded with 100 MeV Si(7+) ions with fluences in the range (7.81-15.62)×10(12)ions cm(-2). The characteristic emission peaks at 481,574, 664 and 754 nm recorded in both IL and PL are attributed to the luminescence centers activated by Dy(3+) ions. It is found that IL and PL emissions intensity decreases with increase in Si(7+) ion fluence. The decrease in intensity can be due to the destruction of Si-O-Si and O-Si-O type species present on the surface of the sample. FTIR studies also confirm the Si-O-Si and O-Si-O type species observed to be sensitive for swift heavy ion (SHI) irradiated samples.
Available from: Vinay Kumar
- "Among the rare earth ions, Dy 3+ is of much interest because of the existence of two characteristic emission bands in the blue (∼480 nm) and yellow (∼570 nm) regions, which correspond to the magnetic dipole transition ( 4 F 9/2 → 6 H 15/2 ) and the hypersensitive electric dipole transition ( 4 F 9/2 → 6 H 13/2 ) of Dy 3+  . In addition, the intensity of the yellow emission is strongly affected by the crystal field environment of the host lattice and the radial integral of 4f and 5d electrons . Hence, the white light could be produced by tailoring the yellow to blue (Y/B) intensity ratio. "
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ABSTRACT: A near-ultra violet (UV) converted LiMgBO3:Dy3+ nanophosphors have been synthesized by the combustion method. The structural, spectral and optical properties were examined by powder X-ray diffraction, fluorescent spectrophotometry and UV–vis spectroscopy. The excitation spectra of the phosphors contain sharp peaks at 294, 323, 348 and 385 nm due to the 4f–4f transition of the Dy3+ ion. The phosphor is effi-ciently excited by near-UV chips. Upon near-UV excitation the phosphor emits intense blue and yellow with a weak red band centered at 484, 573 and 669 nm respectively, ascribed to the transition of Dy3+ ion from 4F9/2→6H15/2, 6H13/2, 6H11/2. The diffuse reflectance spectra of the phosphors were consistent with the excitation spectra and were used to calculate the band gap of the material, approximated to be 5.4 eV. The calculated CIE coordinates (0.45, 0.46) under 348 nm excitation were found to be in the white spectrum region. For surface investigation, X-ray photoelectron spectroscopy was used which confirms the presence of all the elements on the surface of the material.
Applied Surface Science 02/2015; 329:40-46. DOI:10.1016/j.apsusc.2014.12.056 · 2.71 Impact Factor
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ABSTRACT: ZnAl2O4:Dy3+ (1-9 mol%) nanophosphors were synthesized by a simple, cost effective and environmental friendly route using Euphorbia tirucalli plant latex. The structural properties and morphological features of the phosphors were well studied by PXRD, FTIR, SEM and TEM measurements. The luminescent properties of ZnAl2O4:Dy3+ (1-9 mol%) nanophosphors were investigated from the excitation and emission spectra. The phosphor performance was evaluated by color co-ordinates. The values were well located in the near white region as a result it was highly useful for the fabrication of green component in WLEDs. The average particle size was found to be similar to 9-18 nm and same was confirmed by TEM and Scherrer's method. The highest photoluminescence (PL) and thermoluminescence (TL) intensity was obtained to be similar to 7 mol% Dy3+ concentration. A single TL glow peak was recorded at 172 degrees C at a warming rate of 2.5 degrees Cs (1). The intensity at 172 degrees C peak increases linearly up to 1 kGy and after that it diminishes. PL intensity was studied with different plant latex concentration (2-8 ml) and highest PL intensity was recorded for similar to 8 ml. The optimized phosphor showed good reusability, low fading and wide range of linearity with gamma-dose hence the phosphor was quite useful in radiation dosimetry.
Journal of Alloys and Compounds 02/2014; 585:561-571. DOI:10.1016/j.jallcom.2013.09.080 · 3.00 Impact Factor
Available from: Odireleng Martin Ntwaeaborwa
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ABSTRACT: The effect of 120 MeVAg9? ion irradiation on
the structural, optical and luminescence properties of
NaSr1-xBO3:xDy3? (x = 0.5–2.5 mol%) phosphor synthesized
by the conventional solid state reaction route is
reported. The samples were irradiated with Ag9? swift
heavy ions (SHIs) using fluences of 1 9 1012, 5 9 1012
and 1 9 1013 ions cm-2. The unirradiated as well as
irradiated samples were characterized by powder X-ray
diffraction (PXRD), diffuse reflectance (DR) and photoluminescence
techniques. PXRD confirms no change in the
phase after irradiation except that loss of crystallinity had
been observed which may be due to the fragmentation
caused by the SHI. A blue shift in the absorption band of
the DR was observed, resulting in an increase in the band
gap from 5.61 eV to 5.77 eV, after ion irradiation. An
increase in photoluminescence intensity (excited at
385 nm) was observed with increased ion fluences. The
ratio of the blue to yellow emission peaks (I483/I577) was
calculated and found to be varying with ion fluences suggesting
that the white light can be achieved by tailoring this
yellow to blue ratio. The Commission Internationale de
l’Eclairage coordinates were calculated and found to move
toward the white region after irradiation.
Journal of Materials Science 06/2014; DOI:10.1007/s10853-014-8367-0 · 2.37 Impact Factor
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