Synthesis of luminescent nanocrystals and solid solutions in the YNbO{sub 4}–EuNbO{sub 4} system via hydrothermal route

Journal Article · Sat Feb 01 04:00:00 EST 2014 · Materials Research Bulletin

DOI:https://doi.org/10.1016/J.MATERRESBULL.2013.10.041· OSTI ID:22345214

Hirano, Masanori; Dozono, Hayato

Highlights: • Nanocrystals: YNbO{sub 4}:Eu{sup 3+} were directly formed under hydrothermal conditions at 240 °C. • The nanocrystals (10–20 nm) were luminescent and had ellipsoidal morphology. • The complete solid solutions in the YNbO{sub 4}–EuNbO{sub 4} system were also directly formed. • The PL intensity and R/O intensity ratio changed depending on heating temperature. - Abstract: Luminescent nanocrystals having distinctive ellipsoidal morphology and the complete solid solution of monoclinic phase in the YNbO{sub 4}–EuNbO{sub 4} system were hydrothermally formed under weakly basic conditions at 180–240 °C for 5 h. The excitation spectra of the Y{sub 1−x}Eu{sub x}NbO{sub 4} nanocrystals, which consisted of the charge transfer (CT) band around 240–270 nm due to [NbO{sub 4}]{sup 3−}–Eu{sup 3+} interaction and several sharp bands corresponding to the f–f transitions of Eu{sup 3+}, e.g. the most intense absorption band at 395 nm ({sup 7}F{sub 0}→{sup 5}L{sub 6}), showed that the compounds could be excited by both ultraviolet and visible light. A dominant red emission at 610 nm and a weak orange emission at 590 nm assigned to {sup 5}D{sub 0}→{sup 7}F{sub 2} and {sup 5}D{sub 0}→{sup 7}F{sub 1} transitions of Eu{sup 3+}, respectively were observed in the as-prepared nanocrystals containing europium under excitation at 395 nm. The heat treatment at temperatures more than 1000 °C in air was effective for the improvement in the photoluminescence intensity of the as-prepared solid solutions. By the enhancement in the crystallinity and crystallite growth of the monoclinic phase through heat treatment at 1300 °C in air, the luminescence intensity of the as-prepared solid solution, Y{sub 0.75}Eu{sub 0.25}NbO{sub 4} (x = 0.25), which showed the most significant photoluminescence, became more than 5 times as strong as that before the heat treatment.

• OSTI ID: 22345214
• Journal Information: Materials Research Bulletin, Journal Name: Materials Research Bulletin Vol. 50; ISSN MRBUAC; ISSN 0025-5408
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
77 NANOSCIENCE AND NANOTECHNOLOGY
ABSORPTION
EUROPIUM IONS
EXCITATION
HEAT TREATMENTS
INTERACTIONS
NANOSTRUCTURES
OPTICAL PROPERTIES
OXIDES
PHOTOLUMINESCENCE
SOLID SOLUTIONS
SPECTRA
SYNTHESIS
X-RAY DIFFRACTION