Studies on the influence of structure units on the state of ytterbium ions in TeO 2 -based glasses
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Studies on the influence of structure units on the state of ytterbium ions in TeO2-based glasses Yonggang Liu1,a), Zhongyuan Lu2,b), Jianjie Xu3, Tengxiao Guo3 1
Analytical and Testing Center, Southwest University of Science and Technology, Mianyang 621010, China; and Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China 2 State Key Laboratory of Environment-friendly Energy Materials, Southwest University of Science and Technology, Mianyang 621010, China 3 State Key Laboratory of NBC Protection for Civilian, Beijing 102205, China a) Address all correspondence to these authors. e-mail: [email protected] b) e-mail: [email protected] Received: 10 November 2019; accepted: 15 January 2020
A simple composition of TeO2–Yb2O3 binary glass was selected as the host glass matrix for discussing the structure of tellurite glass with increasing Yb2O3 content. Raman spectra were measured to investigate the structure of the binary tellurite glasses, and upconversion and downconversion fluorescence characteristics were employed for discussing the relationship between the structural units and the state of Yb3+ in the tellurite glasses. The results suggested that the decrease of TeO4/2 in the glasses would result in the formation of Yb3+ clusters and Yb3+–O2− couple in the tellurite glasses, and then results in the decrease of cooperative upconversion and downconversion fluorescence intensity.
Introductions Over the past decades, rare earth ion–doped glasses find great applicability in lasers, display, wavelength up and down convertors, and various other fields [1, 2, 3, 4, 5]. Among various host glass matrixes, tellurite was of particular interest to researchers because of its wide transmittance range, lower maximum phonon energy, good physical and chemical stability, and easy fabrication, which have virtual applications in fiber lasers and amplifiers, and upconversion and downconversion convertors [6, 7, 8]. It is well known than pure tellurium oxide is hard to transfer into glass because of the presence of a paired electron in the equatorial region of TeO4 trigonal bipyramids found in the tellurium oxide network [9]. To obtain tellurite glass, alkali oxides, rare earth oxides have been added into TeO2 activating as modifying oxide to balance the redundant electrons. Commonly, the introduced rare earth ions acted as modifiers, which would break the network constructed by TeO4 trigonal bipyramids. With increasing doping concentration, TeO4 trigonal bipyramids were progressively transformed into TeO3 trigonal pyramid structure (tps). Then, rare earth ions were distributed into the gap between the structural units of the glass. The fluorescence characteristics of the rare earth ions in tellurite glass were closely related to the surrounding environment, the
ª Materials Research Society 2020
distance between neighboring ions, clusters etc. Many previous works have been devoted to construct the glass structure of tellurite glasses from classical molecular dynamics (MD) simulations to various methods
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