Tunable emission and optical trapping of upconverting LiYF4:Yb, Er nanocrystal. (June 2020)

• Record Type: Journal Article
• Authors: Anbharasi, L.; Bhanu Rekha, E.A.; Rahul, V.R.; Roy, Basudev; Gunaseelan, M.; Yamini, S.; Adusumalli, Venkata N.K.B.; Sarkar, Debashrita; Mahalingam, Venkataramanan; Senthilselvan, J.
• Is Part Of: Optics & laser technology. Volume 126(2020)
• Publication Date: 2020-06
• Subjects: Upconversion -- Optical tweezer -- Optical trapping -- Nanocrystal -- Tunable emission -- LiYF4:Yb, Er; Optics -- Periodicals; Lasers -- Periodicals; Electronic journals; 621.366
• DOI: 10.1016/j.optlastec.2020.106109
• Languages: English
• ISSNs: 0030-3992

Abstract

Graphical abstract: Highlights: First result on optical trapping of LiYF4 :Yb, Er nanocrystal at NIR 980 nm laser. Optical trapping of ~238 nm size nanocrystal with an optical force 10.8 fN at 50 mW. Surfactant free hydrothermal synthesis of LiYF4 :Yb, Er upconversion nanocrystal. Calcination temperature dependent upconversion Yellow, Green, Red color tuning. Multifaceted tetragonal nanocrystals induce high scattering and optical trapping. Abstract: Present work investigates about hydrothermally prepared LiYF4 :Yb, Er nanocrystals with novel tunable emission and optical trapping results. Optical trapping effect of LiYF4 :Yb, Er upconversion nanocrystal under 980 nm diode laser interaction is reported and a single nanoparticle trapping is demonstrated. Optical trapping force of 10.8 fN is exerted on LiYF4 :Yb, Er upconversion nanocrystal of size ~238 nm at laser power 50 mW and the result is in agreement with the reported values. At 980 nm excitation, tunable green to red upconversion emission is achieved by calcination. It depends on orthorhombic and tetragonal phases that confirmed by XRD. The nanocrystals calcined at 450 and 600 °C resulted in a decay time of 26 and 19 µs respectively and the upconversion emission mechanism is explained. FESEM and HRTEM examinations showed the hydrothermally synthesized nanocrystals are in trapezohedral, pyramidal, bi-pyramidal and tetragonal morphologies. The differential scanning calorimetry revealed the tetragonal phase formation temperature is lower at 450 °C compared to the reported value of 750 °C. The UV–VIS-NIR spectra of LiYF4 :Yb, Er showed high absorption at 380, 480, 520 and 660 nm due to Er 3+ ion and the broad absorption from 900 to 1000 nm centered at 980 nm is owing to Yb 3+ ion. The crystalline phase, morphology, upconversion emission and optical trapping behaviors of LiYF4 :Yb, Er nanocrystal are explained elaborately.