Observation of exceptional strong emission transitions 5Dj (j=1−3) to 7Fj (j=1−3): Multicolor from single Eu3+ ion doped La2O3 nanoparticles

• Published in: Journal of luminescence 2013-02, Vol.134, p.14-23
• Main Authors: Loitongbam, Romeo Singh, Singh, N. Shanta, Singh, W. Rameshwor, S. Ningthoujam, R.
• Format: Article
• Language: English
• Subjects: Bands; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Electronics; Emission; Exact sciences and technology; Excitation; Heat treatment; La2O3; Luminescence; Materials science; Nanocrystalline materials; Nanocrystals and nanoparticles; Nanoparticles; Nanoscale materials and structures: fabrication and characterization; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures; Photoluminescence; Physics; Polyvinyl alcohols; White light
• ISSN: 0022-2313; 1872-7883
• DOI: 10.1016/j.jlumin.2012.09.026

Eu3+ ion doped La2O2CO3 and La2O3 nanoparticles have been synthesized through hydrothermal route with subsequent heat-treatment. It is found that La2O2CO3 phase is highly stable at ambient atmosphere and decomposes to La2O3 at or above 700°C. Exceptional stronger emissions from 5Dj (j=1−3) to 7Fj (j=1−3) transitions are observed compared to most probable 5D0 to 7Fj (j=1−3) transitions in 1 and 3at% Eu3+ doped samples heated at 900°C under 278nm excitation. This may be ascribed due to minimum cross-relaxation among 5Dj (j=1−3) levels. Significant decrease of emission intensity from 5D1 or 5D2 level and subsequent increase of emission intensity from 5D0 level on increasing Eu3+concentration up to 10at% indicate relaxation of excited electrons from 5Dj=1, 2 to 5D0 level. Excitation at 394nm shows strong background emission intensity in 425–600nm due to different defect states/intermediate bands present within host electronic band. Colors including blue, green, yellow, pink and red to white could be produced by changing concentration of Eu3+, excitation wavelength and annealing temperature. Samples are dispersible and could be incorporated in polyvinyl alcohol (PVA) films. Materials will also be potential candidates for light emitting diodes (LEDs) and bio-labeling. ► As prepared samples shows biphasic nature. ► La2O3 is sensitive to ambient environment. ► Exceptional strong emission transitions of 5Dj (j=1−3) to 7Fj (j=1–3). ► Multicolor tuning from singly doped La2O3.