The crystal structure, vibrational and luminescence properties of the nanocrystalline KEu(WO{sub 4}){sub 2} and KGd(WO{sub 4}){sub 2}:Eu{sup 3+} obtained by the Pechini method
- Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wroclaw 2 (Poland)
The luminescent nanocrystalline KEu(WO{sub 4}){sub 2} and KGd{sub 0.98}Eu{sub 0.02}(WO{sub 4}){sub 2} have been prepared by the Pechini method. X-ray diffraction, infrared and Raman spectroscopy as well as optical spectroscopy were used to characterise the obtained materials. The crystal structure of KEu(WO{sub 4}){sub 2} was refined in I2/c space group indicating the isostructurality to KGd(WO{sub 4}){sub 2}. The size of the crystalline grains depended on the annealing temperature, increasing with the increase of the temperature. The average size of crystallites of both crystals formed at 540 deg. C was about 50 nm. Vibrational spectra showed noticeable changes as a function of size due to, among others, phonon confinement effect. Luminescence studies did not reveal significant changes for the nanocrystallites with the lowest grain size in comparison with the bulk material. The differences observed in luminescence spectra in form of slight inhomogeneous broadening of the spectral lines and increase of the hypersensitive I{sub 0-2}/I{sub 0-1} ratio point to very low symmetry of Eu{sup 3+} ions and change of the polarisation of the local vicinities of Eu{sup 3+}. X-ray diffraction, vibrational and optical studies showed that the structure of the synthesised nanocrystalline KEu(WO{sub 4}){sub 2} and KGd(WO{sub 4}){sub 2}:Eu is nearly the same as that found for the bulk material. The size-driven phase transitions were established for both compounds. - Graphical abstract: The luminescent nanocrystalline KEu(WO{sub 4}){sub 2} and KGd{sub 0.98}Eu{sub 0.02}(WO{sub 4}){sub 2} have been prepared by the Pechini method and characterise by using X-ray diffraction, infrared and Raman spectroscopy as well as optical spectroscopy. The crystal structure of KEu(WO{sub 4}){sub 2} was refined in I2/c space group indicating the isostructurality to KGd(WO{sub 4}){sub 2}. The size of the crystalline grains increases with the increase of the annealed temperature. The average size of crystallites of both crystals formed at 540 deg. C was about 50 nm. X-ray diffraction, vibrational and optical studies showed that the structure of the synthesised nanocrystalline KEu(WO{sub 4}){sub 2} and KGd(WO{sub 4}){sub 2}:Eu is nearly the same as that found for the bulk material. The size-driven phase transitions were established for both compounds.
- OSTI ID:
- 21212037
- Journal Information:
- Journal of Solid State Chemistry, Vol. 181, Issue 10; Other Information: DOI: 10.1016/j.jssc.2008.06.026; PII: S0022-4596(08)00310-1; Copyright (c) 2008 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
Similar Records
Study of Semimagnetic Mn-Doped WO{sub 3} Nanoparticles Synthesised by Precipitation Method: Hydrogenation Creates a Promising DMS
Crystal forms of the double molybdates of potassium with samarium, europium, and gadolinium KLn (MoO/sub 4/)/sub 2/
Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ANNEALING
CRYSTALS
EUROPIUM COMPOUNDS
EUROPIUM IONS
GADOLINIUM COMPOUNDS
GRAIN SIZE
LUMINESCENCE
MONOCLINIC LATTICES
NANOSTRUCTURES
PHASE TRANSFORMATIONS
POLARIZATION
POTASSIUM COMPOUNDS
RAMAN SPECTROSCOPY
SPACE GROUPS
SPECTRA
SYMMETRY
TEMPERATURE RANGE 0400-1000 K
TUNGSTATES
X-RAY DIFFRACTION