Blue and NIR emission from nanostructured Tm super(3+)/ Yb super(3+) co-doped SiO sub(2)-Ta sub(2)O sub(5) for photonic applications

• Published in: Journal of physics. D, Applied physics Applied physics, 2016-05, Vol.49 (17), p.175107-175117
• Main Authors: Muscelli, Wesley Cardoso, de Oliveira Lima, Karmel, Aquino, Felipe Thomas, Goncalves, Rogeria Rocha
• Format: Article
• Language: English
• Subjects: Emission; Emissions control; Excitation; Lanthanides; Luminescence; Nanocomposites; Photonics; Silicon dioxide
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/0022-3727/49/17/175107

This paper reports on the synthesis of Tm super(3+)/Yb super(3+) co-doped SiO sub(2)-Ta sub(2)O sub(5) nanocomposites prepared by a sol-gel route. XRD analysis revealed initial crystallization of the L-Ta sub(2)O sub(5) structure dispersed in the silica host, which depended on lanthanide concentration. Vibrational spectroscopy showed low OH groups content, SiO sub(2)-Ta sub(2)O sub(5) nanocomposite formation, and controlled phase separation characterized by the presence of Ta sub(2)O sub(5) nanoparticles. Emission in the near infrared was evident and also depended on lanthanide concentration and excitation wavelength. Direct excitation on the host promoted NIR luminescence; higher intensity emerged at 980 nm, attributed to Yb super(3+) ions. Excitation of the Tm super(3+) excited levels elicited energy transfer between Tm super(3+) and Yb super(3+) ions. Excitation of the Tm super(3+) levels (visible range) and the host (UV) promoted emission in the S telecom band for all the samples. Excitation at 980 nm gave rise to upconversion emissions at 476 nm (blue) and 793 nm (NIR). At higher lanthanide concentration, the presence of a dominant cross-relaxation process reduced the blue emission with respect to the NIR emission. The color coordinates were similar to the coordinates of standard blue. All these luminescent properties make the synthesized materials potential candidates for photonic applications like energy converting devices, solar concentrators, and blue emitters.