Upconversion luminescence of lanthanide-doped mixed CaMoO4–CaWO4 micro-/nano-materials. Issue 30 (11th July 2016)

• Record Type: Journal Article
• Authors: Liu, Jing; Kaczmarek, Anna M.; Billet, Jonas; Van Driessche, Isabel; Van Deun, Rik
• Is Part Of: Dalton transactions. Volume 45:Issue 30(2016)
• Page Start: 12094
• Page End: 12102
• Publication Date: 2016-07-11
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c6dt01555g
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : The synthesis and characterization of Er 3+, Yb 3+ doped mixed CaMoO4 –CaWO4 micro-/nano-upconversion materials is presented in this paper. The relative intensities of the green and red emission bands can be enhanced by heat treatment or through Gd 3+ co-doping. Abstract : Uniform mixed CaMoO4 –CaWO4 micro-/nano-materials have been successfully synthesised by a facile hydrothermal method. The morphology of these upconversion materials could be changed to different shapes and the size could also be decreased from the micro- to nano-scale by varying the type of surfactant used. It was observed that before heat treatment, the materials show relatively weak green light emission under excitation at 975 nm, whereas after heat treatment, the intensity of the upconversion luminescence increases dramatically while the intensity of the red component decreases relatively. By adjusting the molybdate/tungstate ratio, it was found that the samples with a higher molybdate content have stronger luminescence properties. XRD measurements have been done to investigate the structure of the mixed CaMoO4 –CaWO4 upconversion materials. The effect of heat treatment at different temperatures on the emission spectra and XRD patterns has also been studied. TG-DTA was used to further confirm the most suitable temperature for heat treatment. The luminescence lifetimes and CIE coordinates for these samples were also determined. Additionally it was found that Gd 3+ co-doping could further increase the upconversion luminescence from these mixed CaMoO4 –CaWO4 materials. Finally, monitoring the upconversion luminescence intensity as a function of laser pump power confirmed the upconversion process to be a two-photon absorption mechanism.