Synthesis, Characterization and Thermoluminescence Studies of LiNaSO4: Eu3+ Nanophosphor

Na2SO4, LiNaSO4 and LiNaSO4: Eu3+ nanophosphors were successfully synthesized by slow evaporation technique followed by calcination at 400° C. The resultant products were characterized by using powder X- ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), UV – Vis, scanning electron microscope (SEM) and transmission electron microscope (TEM). Doping with Li+ ion stabilized the thenardite phase (Phase V) while, codoping with Eu3+ promoted the phase transformation from stable thenardite to metastable mirabilite (Phase III) crystal structure. The average crystallite size was calculated by using Debye – Scherrer’s formula and Williamson – Hall (W – H) plots. The optical energy band gap (Eg) of Na2SO4, LiNaSO4 and LiNaSO4: Eu3+ were estimated from Wood and Tauc’s relation which varies from 4.2 – 4.33 eV. Thermoluminescence (TL) studies were investigated by using ã – irradiation in the dose range 0.5 – 5 kGy at a heating rate of 5 °C s-1. A well resolved glow peaks at ~ 180 °C, ~ 150 °C and ~115 °C were recorded for Na2SO4, LiNaSO4 and LiNaSO4: Eu3+ nanophosphors respectively. It was observed that isovalent doping of Li+ served as quencher, while codoping of hypervalent Eu3+ acted as activator to enhance the TL intensity of glow peak. In the present study, the extent of TL fading of LiNaSO4: Eu3+ was 31 % compared to LiNaSO4 (52 %) and Na2SO4 (59 %). So, LiNaSO4: Eu3+ phosphor might also have potential use in dosimetry. The kinetic parameters namely activation energy (E), frequency factor (s) and order of kinetics (b) was estimated and the results were discusse

Optical studies in gamma irradiated Mg doped CaF2 single crystals

Pure and Mg doped CaF2 single crystals grown by the Bridgman method were irradiated with gamma rays (gamma-rays) for doses ranging from 97 Gy to 9.72 KGy. The pristine samples showed minimal absorption indicating the purity of the samples. The gamma-irradiated pure CaF2 crystals showed prominent and strong absorption with a peak at similar to 374 nm besides three weak ones at similar to 456, 523 and 623 nm. However gamma-rayed Mg doped crystals showed a prominent absorption with a strong peak at similar to 370 nm and a broad one at similar to 530 nm. The absorption indicated the generation of F and F-aggregate centers in the irradiated crystals. The photoluminescence (PL) emission spectrum of both pure and Mg doped crystals showed prominent emission at similar to 390 nm when they were excited at similar to 250 nm. Also, when the samples were excited at 323 and 363 nm strong emissions were observed at similar to 430 and 422 nm respectively. The optical absorption and PL intensities were found to increase with increase in dose. (C) 2010 Elsevier B.V. All rights reserved

Spectroscopic studies of γ-rayed CaF2:Sr

Optical absorption spectra of gamma irradiated (γ-rayed) Strontium (Sr) doped Calcium fluoride (CaF2) single crystals showed a prominent absorption peak at ∼370 nm and two weak ones at ∼463 and 524 nm. At higher γ-dose the two weak peaks merged into a broad one at ∼520 nm. The Photoluminescence (PL) spectra showed a prominent emission at ∼394 nm when the crystals were excited at ∼240 nm. The excitation of samples at 370 nm showed strong emission at ∼530 nm with a shoulder at ∼465 nm. The optical absorption and PL intensities were found to increase with γ-dose. However, the optical absorption and PL intensities of CaF2:Sr are found to be less than those of undoped CaF2 single crystals

Influence of Li+ and Dy3+ on structural and thermoluminescence studies of sodium sulfate

Na2SO4, Na2SO4:Dy3+, LiNaSO4 and LiNaSO4:Dy3+ nanoparticles were successfully synthesized by slow evapn. technique followed by calcination at 400°. The resultant products were characterized by powder x-​ray diffraction, SEM, TEM, FTIR and UV-​visible spectroscopy. The av. crystallite size was calcd. using Debye-​Scherrer's formula and Williamson-​Hall's (W-​H) plots. The optical energy band gap (Eg) was estd. from Wood and Tauc's relation, which varies from 3.70 to 4.45 eV. The variation in band gap values is attributed to a large degree of structural defects. Thermoluminescence (TL) studies were studied using γ-​irradn. in the dose range 0.5-​5 kGy at a heating rate of 5 K s-​1. The samples Na2SO4 and LiNaSO4 showed a well-​resolved glow peak at ∼180 and ∼170°, resp. The prominent glow peak at ∼175° along with a shouldered peak at ∼60° was obsd. for Na2SO4:Dy3+. LiNaSO4:Dy3+ showed a prominent glow peak at ∼100° and a small shoulder peak at ∼180°. The addn. of isovalent (Li+) quenches the TL intensity, whereas the hypervalent (Dy3+) increases the intensity from Na2SO4. The variations of TL intensity for all the phosphors follow linear behavior up to 5 kGy and were useful in radiation dosimetry. The kinetic parameters (E, b and s) were estd. from the glow peak shape method

Morphology and optical properties of Mg and Sr doped CaF 2 nanocrystals

Magnesium (Mg) and Strontium (Sr) doped Calcium fluoride nanocrystals were synthesized by co-precipitation method. The cubic structure of the samples was confirmed by Powder X-ray diffraction. The average crystallite size of Mg doped samples was found to be ~ 25 nm whereas in Sr doped one it was ~ 35 nm. The morphological features revealed that the nanocrystals were agglomerated, crispy and porous. The as-prepared samples showed the presence of hydroxyl groups. The optical absorption spectrum of as-prepared Mg doped samples showed a strong absorption band peaked at ~ 233 nm whereas the Sr doped one showed a prominent absorption peak at 248 nm. A strong PL emission was observed at ~ 300 nm in Mg doped samples. However, the Sr doped samples showed two prominent emissions at ~ 345 and 615 n

Luminescence studies of europium doped yttrium oxide nano phosphor

Luminescence exhibiting europium doped yttrium oxide (Y 2O 3:Eu 3+) phosphor was prepared by solution combustion method, using disodium ethylene diamine tetra acetic acid (EDTA-Na 2) as fuel at â¼350 °C. Powder X-ray diffraction (PXRD) pattern of Y 2O 3:Eu 3+ revealed the cubic crystalline phase. The morphology of the samples was studied by scanning electron microscopy (SEM) and was foamy, fluffy and porous in nature. Fourier transformed infrared spectroscopy (FTIR) revealed prominent absorption with peaks at 3415, 1435, 875 and 565 cm -1. Optical absorption studies showed the energy gap of the synthesized samples to be 5.4-5.5 eV. The photoluminescence (PL) of Y 2O 3:Eu 3+ exhibiting emission peak at 611 nm under the excitation of 254 nm. Thermoluminescence of γ-irradiated Y 2O 3:Eu 3+ showed two well resolved TL glows with peaks at 460 and 610 K and they were analyzed by glow curve shape method and the activation energies were found to be 0.421 eV and 1.016 eV respectively. © 2012 Elsevier B.V

Photoluminescence and thermoluminescence studies of Mg 2 SiO 4 :Eu 3+ nano phosphor

Nanoparticles of Eu 3+ doped Mg 2 SiO 4 are prepared using low temperature solution combustion technique with metal nitrate as precursor and urea as fuel. The synthesized samples are calcined at 800 °C for 3 h. The Powder X-ray diffraction (PXRD) patterns of the sample reveled orthorhombic structure with α-phase. The crystallite size using Scherer's formula is found to be in the range 50–60 nm. The effect of Eu 3+ on the luminescence characteristics of Mg 2 SiO 4 is studied and the results are presented here. These phosphors exhibit bright red color upon excitation by 256 nm light and showed the characteristic emission of the Eu 3+ ions. The electronic transition corresponding to 5 D 0 → 7 F 2 of Eu 3+ ions (612 nm) is stronger than the magnetic dipole transition corresponding to 5 D 0 → 7 F 1 of Eu 3+ ions (590 nm). Thermoluminescence (TL) characteristics of γ-rayed Mg 2 SiO 4 :Eu 3+ phosphors are studied. Two prominent and well-resolved TL glows with peaks at 202 °C and 345 °C besides a shoulder with peak at ∼240 °C are observed. The trapping parameters-activation energy ( E ) , order of kinetics ( b ) and frequency factor ( s ) are calculated using glow curve shape method and the results obtained are discussed

Thermoluminescence of combustion synthesized yttrium oxide

Pure yttrium oxide (Y 2O 3) was prepared by solution combustion technique using disodium ethylene diamine tetra acetic acid (EDTA-Na 2) as fuel at ~350°C. Powder X-ray diffraction (PXRD) pattern of Y 2O 3 revealed cubic crystalline structure with crystallite size in the range of 18-23nm. The scanning electron microscopy (SEM) indicated the foamy and fluffy nature of the sample. Fourier transformed infrared spectroscopy (FTIR) revealed four prominent absorption with peaks at 3395, 1433, 875 and 566cm -1. From the optical absorption studies the energy gap of the synthesized sample was found to be 5.72eV. Two well resolved thermoluminescence (TL) glows with peaks at 475 and 626K were observed in γ-irradiated Y 2O 3. The glow curves were analyzed and the average activation energy was found to be 0.505 and 0.977eV respectively. © 2011 Elsevier B.V

100MeV Si8+ Ion Induced Luminescence and Thermoluminescence of Nanocrystalline Mg2SiO4:Eu3+

Nanoparticles of Mg2SiO4:Eu3+ have been prepared by the solution combustion technique and the grain size estimated by PXRD is found to be in the range 40-50 nm. Ionoluminescence (IL) studies of Mg2SiO4:Eu3+ pellets bombarded with 100 MeV Si8+ ions with fluences in the range 1.124-22.48×1012 ions cm−2 are carried out at IUAC, New Delhi, India. Five prominent IL bands with peaks at 580 nm, 590 nm, 612 nm, 655 nm and 705 nm are recorded. These characteristic emissions are attributed to the luminescence centers activated by Eu3+ cations. It is found that IL intensity decreases rapidly in the beginning. Later on, the intensity decreases slowly with further increase of ion fluence. The reduction in the ionoluminescence intensity with increase of ion fluence might be attributed to degradation of Si-O (ν3) and Si-O (2ν3) bonds present on the surface of the sample. The red emission with peak at 612 nm is due to characteristic emission of 5D0→7F2 of the Eu3+ cations. Thermoluminescence (TL) studies of Mg2SiO4:Eu3+ pellets bombarded with 100 MeV Si8+ cations with fluences in the range 5×1011 ions cm−2 to 5×1013 ions cm−2 are made at RT. Two prominent and well resolved TL glows with peaks at ∼220 °C and ∼370 °C are observed. It is observed that TL intensity increases with increase of ion fluence. This might be due to creation of new traps during swift heavy ion irradiation.

Photoluminescence and thermoluminescence studies of Mg2SiO4:Eu3+ nano phosphor

Nanoparticles of Eu3+ doped Mg2SiO4 are prepared using low temperature solution combustion technique with metal nitrate as precursor and urea as fuel. The synthesized samples are calcined at 800 degrees C for 3 h. The Powder X-ray diffraction (PXRD) patterns of the sample reveled orthorhombic structure with alpha-phase. The crystallite size using Scherer's formula is found to be in the range 50-60 nm. The effect of Eu3+ on the luminescence characteristics of Mg2SiO4 is studied and the results are presented here. These phosphors exhibit bright red color upon excitation by 256 nm light and showed the characteristic emission of the Eu3+ ions. The electronic transition corresponding to D-5(0) -> F-7(2) of Eu3+ ions (612 nm) is stronger than the magnetic dipole transition corresponding to D-5(0) -> F-7(1) of Eu3+ ions (590 nm). Thermoluminescence (TL) characteristics of gamma-rayed Mg2SiO4: Eu3+ phosphors are studied. Two prominent and well-resolved TL glows with peaks at 202 degrees C and 345 degrees C besides a shoulder with peak at similar to 240 degrees C are observed. The trapping parameters-activation energy (E), order of kinetics (b) and frequency factor (s) are calculated using glow curve shape method and the results obtained are discussed. (C) 2011 Elsevier B.V. All rights reserved