Highly efficient NIR–NIR upconversion in potassium substituted CaMoO4:Tm3+, Yb3+ phosphor for potential biomedical applications. Issue 22 (9th February 2015)

• Record Type: Journal Article
• Authors: Luitel, Hom Nath; Chand, Rumi; Torikai, Toshio; Yada, Mitsunori; Watari, Takanori
• Is Part Of: RSC advances. Volume 5:Issue 22(2015)
• Page Start: 17034
• Page End: 17040
• Publication Date: 2015-02-09
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c4ra12436g
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : Highly efficient NIR to NIR upconversion in CaMoO4 :Tm 3+, Yb 3+ nanocrystals pumped by less than 1 mW laser was achieved for biomedical applications. Abstract : We obtained highly efficient NIR to NIR (excitation by 980 nm, emission at 800 nm) upconversion in CaMoO4 :Tm 3+, Yb 3+, M + (M = Li, Na, K, Rb) nanocrystals synthesized by a hydrothermal method. The XRD patterns show that they are all of tetragonal structure despite a small amount of RE 3+ and M + ion doping. The solid solubility of lithium, sodium, potassium and rubidium ions in the CaMoO4 were found to be 30 mol%, 20 mol%, 10 mol% and 5 mol%, respectively. The doped M + ions affect the crystal field symmetry around Tm 3+ ions in the CaMoO4 host, which results in the change of the irradiation transition probabilities between their transition levels and intensifies the UC intensities. Compared with CaMoO4 :Tm 3+, Yb 3+, the NIR to NIR upconversion emission intensity of CaMoO4 :Tm 3+, Yb 3+, 0.10M + nanocrystals increases 2.2, 3.3, 47 and 10 fold for Li, Na, K and Rb, respectively. The K substituted CaMoO4 :Tm 3+, Yb 3+ phosphor exhibited intense UC emission pumped by less than 1 mW laser power and can have potential application in NIR to NIR photodynamic diagnosis.