Synthesis, structure and luminescence properties of the europium–containing NASICON type phosphates

• Published in: Journal of sol-gel science and technology 2023-02, Vol.105 (2), p.547-554
• Main Authors: Asabina, Elena, Sedov, Vladislav, Pet’kov, Vladimir, Deyneko, Dina, Kovalsky, Andrey
• Format: Article
• Language: English
• Subjects: Ceramics; Chemistry and Materials Science; Composites; Conductors; Crystallization; Differential thermal analysis; Emission spectra; Europium; Glass; Heat treatment; Infrared spectroscopy; Inorganic Chemistry; Luminescence; Luminous intensity; Materials Science; Nanotechnology; Natural Materials; Optical and Electronic Materials; Optical properties; Original Paper: Sol-gel and hybrid materials for optical; Phosphates; Photoluminescence; photonic and optoelectronic applications; Solid solutions; Spectrum analysis; X ray powder diffraction
• ISSN: 0928-0707; 1573-4846
• DOI: 10.1007/s10971-022-06028-z

Synthesis process, structure and luminescent properties of NASICON (Na super ionic conductor) type phosphates doped with europium have been investigated for the Na 1- x Eu 0.33 x Ti 2 (PO 4 ) 3 series. The samples were synthesized via Pechini technique. Differential thermal analysis of the reaction mixtures was used to choose the optimal scheme for the thermal treatment of the phosphates. The obtained samples were studied by means of X-ray powder diffraction (including Rietveld structure refinement), Infrared spectroscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy. It was shown that the phosphates with 0 ≤  x  ≤ 0.1 were crystallized in the space group R 3 ¯ c , while the phosphates with 0.2 ≤  x  ≤ 1.0 characterized by the space group R 3 ¯ . Photoluminescence emission spectra of the phosphates Na 1- x Eu 0.33 x Ti 2 (PO 4 ) 3 showed typical emission bands of Eu 3+ ions, due to 5 D 0 → 7 F J transitions. The intensity of the emission bands rises with the concentration of europium up to x  = 0.7 (Na 0.3 Eu 0.23 Ti 2 (PO 4 ) 3 ), while a further increase of x results into concentration quenching. Graphical Abstract Na 0.5 Eu 0.167 Ti 2 (PO 4 ) 3 structure and Na 1- x Eu 0.33 x Ti 2 (PO 4 ) 3 photoluminescence emission spectra Highlights The Na 1- x Eu 0.33 x Ti 2 (PO 4 ) 3 series were synthesized via Pechini technique. The phosphates formed solid solutions with space groups R 3 ¯ c ( 0 ≤ x ≤ 0.1 ) and R 3 ¯ ( 0.2 ≤ x ≤ 1.0 ) . The Rietveld XRD study of the phosphate Na 0.5 Eu 0.167 Ti 2 (PO 4 ) 3 ( x = 0.7) was performed. The compounds were characterized as perspective luminophores of red light. The phosphate Na 0.3 Eu 0.23 Ti 2 (PO 4 ) 3 showed maximum intensity of the emission bands.