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Enhancement of luminescence in white emitting strontium fluoride core @ calcium fluoride shell nanoparticles.

Kumam N, Singh NP, Singh LP, Srivastava SK - Nanoscale Res Lett (2015)

Bottom Line: The size of the nanoparticles for core (SrF2:3Dy) is found to increase when core is covered by shell (CaF2).The calculated correlate colour temperature (CCT) values for SrF2:3Dy, SrF2:3Dy@CaF2 (1:0.05), SrF2:3Dy@CaF2 (1:1) and SrF2:3Dy@CaF2 (1:2) are 5475, 5476, 5384 and 5525 K, respectively, which lie in the cold white region.Graphical abstract White light emitting homonanostructure material SrF2:3Dy@CaF2(core@shell).

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Manipur University, Imphal, 795003, India.

ABSTRACT
Synthesis of lanthanide-doped fluoride SrF2:3Dy and SrF2:3Dy@CaF2 nanoparticles with different ratios of core to shell (1:0.5, 1:1 and 1:2) has been carried out by employing ethylene glycol route. X-ray diffraction (XRD) patterns reveal that the structure of the prepared nanoparticles was of cubical shape, which is also evident in TEM images. The size of the nanoparticles for core (SrF2:3Dy) is found to increase when core is covered by shell (CaF2). It is also evident from Fourier transform infrared spectroscopy (FTIR) that ethylene glycol successfully controls the growth and acts as a shape modifier by regulating growth rate. In the photoluminescence investigation, emission spectra of SrF2:3Dy is found to be highly enhanced when SrF2:3Dy is covered by CaF2 due to the decrease of cross relaxation amongst the Dy(3+)-Dy(3+) ions. Such type of enhancement of luminescence in homonanostructure SrF2:3Dy@CaF2 (core@shell) has not been studied so far, to the best of the authors' knowledge. This luminescent material exhibits prominently white light emitting properties as shown by the Commission Internationale d'Eclairage (CIE) chromaticity diagram. The calculated correlate colour temperature (CCT) values for SrF2:3Dy, SrF2:3Dy@CaF2 (1:0.05), SrF2:3Dy@CaF2 (1:1) and SrF2:3Dy@CaF2 (1:2) are 5475, 5476, 5384 and 5525 K, respectively, which lie in the cold white region. Graphical abstract White light emitting homonanostructure material SrF2:3Dy@CaF2(core@shell).

No MeSH data available.


Related in: MedlinePlus

a Excitation spectra of SrF2:3Dy core nanoparticles and its CaF2 shell at different ratios of shells monitor at 575-nm emission wavelength. b Emission spectra of SrF2:3Dy@CaF2 (1:2) monitor at two different excitation wavelengths 240 and 349 nm
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Fig5: a Excitation spectra of SrF2:3Dy core nanoparticles and its CaF2 shell at different ratios of shells monitor at 575-nm emission wavelength. b Emission spectra of SrF2:3Dy@CaF2 (1:2) monitor at two different excitation wavelengths 240 and 349 nm

Mentions: Figure 5a shows the excitation spectra of the SrF2:3Dy and SrF2:3Dy@CaF2 at two different ratios of shell monitored at 575-nm emission wavelength. In order to study the excitation spectra, we can divide the whole spectrum into two regions, one in the range 200–280 nm and another is 280–400 nm. The region from 200–280 nm corresponds to the transition from 2p orbital of F− ions to the 4f orbital of Dy3+ ions (charge transfer transition) and consists of peaks at 239, 256 and 277 nm. The peaks from 280–400 nm are related with the 4f-4f transition of Dy3+ ion. The peak at 349, 363, 386, 435, 453 and 474 nm can be assigned to the transition from 6H15/2 to 6P7/2 ,6P5/2 , 4I13/2 , 4G11/2 ,4I15/2 and from 4F9/2 to 4H15/2 of Dy3+ ion [25].Fig. 5


Enhancement of luminescence in white emitting strontium fluoride core @ calcium fluoride shell nanoparticles.

Kumam N, Singh NP, Singh LP, Srivastava SK - Nanoscale Res Lett (2015)

a Excitation spectra of SrF2:3Dy core nanoparticles and its CaF2 shell at different ratios of shells monitor at 575-nm emission wavelength. b Emission spectra of SrF2:3Dy@CaF2 (1:2) monitor at two different excitation wavelengths 240 and 349 nm
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4554543&req=5

Fig5: a Excitation spectra of SrF2:3Dy core nanoparticles and its CaF2 shell at different ratios of shells monitor at 575-nm emission wavelength. b Emission spectra of SrF2:3Dy@CaF2 (1:2) monitor at two different excitation wavelengths 240 and 349 nm
Mentions: Figure 5a shows the excitation spectra of the SrF2:3Dy and SrF2:3Dy@CaF2 at two different ratios of shell monitored at 575-nm emission wavelength. In order to study the excitation spectra, we can divide the whole spectrum into two regions, one in the range 200–280 nm and another is 280–400 nm. The region from 200–280 nm corresponds to the transition from 2p orbital of F− ions to the 4f orbital of Dy3+ ions (charge transfer transition) and consists of peaks at 239, 256 and 277 nm. The peaks from 280–400 nm are related with the 4f-4f transition of Dy3+ ion. The peak at 349, 363, 386, 435, 453 and 474 nm can be assigned to the transition from 6H15/2 to 6P7/2 ,6P5/2 , 4I13/2 , 4G11/2 ,4I15/2 and from 4F9/2 to 4H15/2 of Dy3+ ion [25].Fig. 5

Bottom Line: The size of the nanoparticles for core (SrF2:3Dy) is found to increase when core is covered by shell (CaF2).The calculated correlate colour temperature (CCT) values for SrF2:3Dy, SrF2:3Dy@CaF2 (1:0.05), SrF2:3Dy@CaF2 (1:1) and SrF2:3Dy@CaF2 (1:2) are 5475, 5476, 5384 and 5525 K, respectively, which lie in the cold white region.Graphical abstract White light emitting homonanostructure material SrF2:3Dy@CaF2(core@shell).

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Manipur University, Imphal, 795003, India.

ABSTRACT
Synthesis of lanthanide-doped fluoride SrF2:3Dy and SrF2:3Dy@CaF2 nanoparticles with different ratios of core to shell (1:0.5, 1:1 and 1:2) has been carried out by employing ethylene glycol route. X-ray diffraction (XRD) patterns reveal that the structure of the prepared nanoparticles was of cubical shape, which is also evident in TEM images. The size of the nanoparticles for core (SrF2:3Dy) is found to increase when core is covered by shell (CaF2). It is also evident from Fourier transform infrared spectroscopy (FTIR) that ethylene glycol successfully controls the growth and acts as a shape modifier by regulating growth rate. In the photoluminescence investigation, emission spectra of SrF2:3Dy is found to be highly enhanced when SrF2:3Dy is covered by CaF2 due to the decrease of cross relaxation amongst the Dy(3+)-Dy(3+) ions. Such type of enhancement of luminescence in homonanostructure SrF2:3Dy@CaF2 (core@shell) has not been studied so far, to the best of the authors' knowledge. This luminescent material exhibits prominently white light emitting properties as shown by the Commission Internationale d'Eclairage (CIE) chromaticity diagram. The calculated correlate colour temperature (CCT) values for SrF2:3Dy, SrF2:3Dy@CaF2 (1:0.05), SrF2:3Dy@CaF2 (1:1) and SrF2:3Dy@CaF2 (1:2) are 5475, 5476, 5384 and 5525 K, respectively, which lie in the cold white region. Graphical abstract White light emitting homonanostructure material SrF2:3Dy@CaF2(core@shell).

No MeSH data available.


Related in: MedlinePlus