Synthesis and properties of submicron range CaSO4:Eu particles

Patil, Rashmi S.; Muthal, P. L.; Dhopte, S.M.; Kondawar, V. K.; Moharil, S. V.

doi:10.1016/j.jlumin.2006.10.022

Cited by 18 publications

(5 citation statements)

References 19 publications

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“…The OSL decay curves taken with the filters of different wavelengths are also shown in the inset.It could be seen in the figure that there are two prominent peaks (bands) appear one Eu 2+ transitions and are almost similar to the ones observed in photoluminescence (PL) studies. These results are also similar to the results already available in the literature[46,53]. As reported earlier[28,45,54], in CaSO4:Eu, Eu exists in the divalent as well as the trivalent state in the CaSO4 lattice and emits fluorescence on both the valency states.…”

supporting

confidence: 92%

“…The doped impurity could also coexist in the host as Eu2+ or Eu 3+ but their concentrations may change due to redox reactions on annealing at higher temperatures as well as on irradiations. For example, most of the Eu 3+ impurity ions have been found to convert in to Eu 2+ on annealing beyond 925 o C but not much conversion was observed on irradiation to -rays by Patil et al[46] in their submicron particles. But conversion from Eu 3+ to Eu 2+ has mostly been observed on annealing at temperatures more than 800 o C. However, in our CaSO4:Eu@900 sample we could also found Eu 3+ to Eu 2+ conversions (discussed below in Section 3.7).…”

mentioning

confidence: 93%

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Thermoluminescence, photoluminescence and optically stimulated luminescence characteristics of CaSO4:Eu phosphor: Experimental and density functional theory (DFT) investigations

Mandlik

Rondiya

Dzade

et al. 2020

Journal of Luminescence

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The CaSO4:Eu phosphor in nanocrystalline form was obtained by chemical method. The sample was annealed at various temperatures and quenched. The structural, electronic and optical properties are studied using various experimental techniques. As synthesized CaSO4:Eu particles have nanorod shapes with diameter of ~15 nm and length of ~250 nm. After annealing (at around 900 °C) a significant increase in their size (~2-4 μm) with phase transformation from hexagonal to orthorhombic was observed. Thermoluminescence (TL) and optically stimulated luminescence (OSL) intensities were found to increase with temperatureup to 900 °C and decrease thereafter for 1 Gy of test dose of -rays from 90 Sr-90 Yr source. However, the maximum OSL sensitivity was found to be more than that of CaSO4:Eu microcrystalline phosphor (prepared by acid recrystallization method) contrary to the usually found in the literature but much less than that of commercially available α-Al2O3:C phosphor. The activation energy for thermally assisted OSL process was found to be 0.0572 ± 0.0028 eV. The dose ranges of TL and OSL response was found from 0.04 Gy to 100 Gy and 0.02 Gy to 100 Gy, respectively. The experimental results are also correlated with computational calculations based on density functional theory (DFT). The crystal structures and electronic structures of both hexagonal and orthorhombic CaSO4 and CaSO4:Eu materials show that they are direct bandgap (5.67−5.86 eV) insulators, with Ca 2+

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supporting

confidence: 92%

mentioning

confidence: 93%

Thermoluminescence, photoluminescence and optically stimulated luminescence characteristics of CaSO4:Eu phosphor: Experimental and density functional theory (DFT) investigations

Mandlik

Rondiya

Dzade

et al. 2020

Journal of Luminescence

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“…In the decomposition of CaS:Eu to CaSO 4 :Eu, an emission peak at 385 nm is expected. 34,35 The PL emission spectrum of the uncoated and 20 nm thick aluminum oxide layer coated phosphor layers at an excitation wavelength of 275 nm and room temperature is presented in Fig. 2b.…”

Section: Resultsmentioning

confidence: 99%

Microencapsulation of Moisture-Sensitive CaS:Eu[sup 2+] Particles with Aluminum Oxide

Avci¹,

Musschoot²,

Smet³

et al. 2009

J. Electrochem. Soc.

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Single-crystal, submicrometer-sized CaS:Eu luminescent particles were synthesized via a solvothermal route, and these moisturesensitive particles were coated with aluminum oxide using atomic layer deposition ͑ALD͒. Photoluminescence ͑PL͒ spectra of coated and uncoated particles were compared. They both showed a broad-band PL emission with a maximum of 650 nm. Microencapsulation by aluminum oxide layers did not have a pronounced effect on the intensity of the emission. In situ luminescence measurements during the accelerated aging ͑80°C, 80% relative humidity͒ of coated and uncoated CaS:Eu particles were performed. While the uncoated phosphor was largely degraded within 30 h of aging, it was observed that a 20 nm thick aluminum oxide coating dramatically increased the resistance of the luminescent material against moisture, showing the conformity of the Al 2 O 3 coating by the ALD process. Upon degradation, CaCO 3 was formed, leading to Eu 3+ emission as observed in cathodoluminescence. Finally, the use of these coated particles as a wavelength conversion material in light-emitting diodes was evaluated.

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“…The spectra show a broad intense band with maximum at 324 nm along with additional weak excitation bands at 274, 314 and 358 nm, which are due to Eu 2 + ions. Patil et al [31] also observed the excitation bands of Eu 2 + around 270, 319, 338 and 352 nm in CaSO 4 :Eu 2 + phosphor. Upon 324 nm excitation, the emission spectrum of as-prepared LaMgAl 11 O 19 :Eu shows a broad band at 450 nm (blue emission) corresponding to 4f 6 5d-4f 7 transition of Eu 2++ ions.…”

Section: Scanning Electron Microscopymentioning

confidence: 87%