Ce3+ emission in hexagonal and orthorhombic phases of CaSO4

Embedding rare earth compounds and inorganic materials in polymer matrix are of great interest due to its various applications in sensors, optical batteries etc. The hydrated form of optical compounds possesses interest due to the possibility of crystal field effect on the electronic and magnetic field structure of the 4f shell. The stiochiometric cerium compounds have attracted attention due to its high temperature phase stability, high melting point, low thermal conductivity, optical fluorescence etc. In this paper we discuss the synthesis of cerrous sulphate Ce2(SO4)3, Cerium fluoride CeF3and Cerium Phosphate doped with terbium Ce1-xPO4:Tbxcomposites and dependence of their structural and optical behavior on particle size. Cerrous sulphate exists in several phases, mostly hydrated. In polymer composite the anhydrous phase of Ce2(SO4)3is observed. Also CePO4composites crystallize to monazite phase. The significant changes in Ce3+emission and absorption spectra are observed due to this phase change. Cerium fluoride composites prepared with different concentration show three absorption peaks around 237, 275 and 265nm. The lower concentration of CeF3shows different absorption. CePO4composites doped with various concentrations of terbium shows intense green emission at 543 nm and maximum energy transfer for 10 mol % of Tb3+. The Ce3+emission is shifted to 337nm. The S.E.M. photograph of the composite shows well separated particles with average size 300nm.

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“…6(g, h)). No systematic decrease in intensity with the molar concentration is observed in contrast to the other system [11,12]. Fig.…”

Section: Resultsmentioning

confidence: 90%

Structural and Optical Behavior of nanoCe2(SO4)3, CeF3 and CePO4:Tb3+ Composites Embedded in PVOH Matrix

Muley

Joshi²,

Patil

et al. 2013

AMR

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“…1 shows the XRD spectra of CaSO4:Eu nanophosphor, which confirms that the asprepared CaSO4:Eu sample is in hexagonal phase (JCPDS File No. 43-0606) [34,43], while the sample annealed at 900 °C (i.e., CaSO4:Eu@900) is in the orthorhombic phase (JCPDS Card No.…”

Section: Structural Properties Of Caso4:eumentioning

confidence: 99%

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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“…Some studies have been devoted to the thermoluminescence properties of cerium doped calcium sulfate [21][22][23]. Recently TL properties of CaSO 4 :Dy nanoparticles has been studied [6], but synthesis and TL of CaSO 4 :Ce nanosheets has not been reported yet.…”

Section: Introductionmentioning

confidence: 99%