Effect of Li+ on frequency upconversion and intrinsic optical bistability of Ho3+/Yb3+ co-doped gadolinium tungstate phosphor. (August 2018)

• Record Type: Journal Article
• Authors: Yadav, R.V.; Singh, A.K.; Bahadur, A.; Yadav, T.P.; Yadav, R.S.; Rai, S.B.
• Is Part Of: Journal of physics and chemistry of solids. Volume 119(2018)
• Page Start: 138
• Page End: 146
• Publication Date: 2018-08
• Subjects: Rare earth -- Gadolinium tungstate phosphor -- Bistability -- Lithium ion; Solids -- Periodicals; Solides -- Périodiques; Solids; Periodicals; 530.41
• DOI: 10.1016/j.jpcs.2018.03.041
• Languages: English
• ISSNs: 0022-3697

Abstract

Abstract: This paper reports frequency upconversion and intrinsic optical bistability in the Ho 3+ /Yb 3+ co-doped gadolinium tungstate phosphor. The structural analyses confirm the formation of two monoclinic crystalline phases iso-structural to Gd2 WO6 and Gd2 (WO4 )3 with the space groups I2/a and C2/c, respectively. The phase fraction of the two monoclinic phases varies with Li + concentrations. The Ho 3+ /Yb 3+ co-doped phosphors show intense upconversion (UC) emission on excitation with 976 nm. Addition of Li + ion enhances the UC emission intensity of Ho 3+ /Yb 3+ co-doped phosphors significantly. The mechanisms involved in UC emissions have been discussed using pump power dependence analysis and energy level diagram. A hysteresis loop has been observed for Ho 3+ /Yb 3+ co-doped phosphors in increasing and decreasing pump power versus emission intensity curves at room temperature. The polarity of the hysteresis loop is found to be reversed on addition of Li + in the Ho 3+ /Yb 3+ co-doped phosphors. These phosphors can be a potential candidate for optical switching devices. Graphical abstract: Highlights: Ho 3+ /Yb 3+ co-doped gadolinium tungstate phosphor have been synthesized by solid state reaction technique. The structural analyses confirm the formation of two monoclinic crystalline phases Gd2 WO6 and Gd2 (WO4 )3 . It show intense upconversion (UC) emission and intrinsic optical bistability on excitation with 976 nm. The polarity of the hysteresis loop is found to be reversed on addition of Li + .