Abstract:
Background Yb(TMHD)3 (ytterbium tris (2,2,6,6-tetramethyl-3,5-heptanedionate)) is the irreplaceable vapor-phase dopant for fabricating high-gain Yb-doped silica laser fibers, and its exact Yb content dictates final fiber performance. The conventional oxalate gravimetric method requires 6 h per sample, incompatible with the real-time feedback demanded by modern preform manufacture.
Purpose In order to enhance the production efficiency,
Methods we report a “nitric acid-hydrogen peroxide open-vessel digestion/EDTA complexometric titration” protocol. After 3 min oxidative decomposition of the organic matrix, the solution is buffered with hexamethylenetetramine (pH=5-6) and titrated with standard EDTA using xylenol orange (XO) as indicator.
Results The stoichiometric Yb3+ : EDTA ratio is 1∶1; the sharp colour change from rose-red to bright yellow is achieved, with a relative standard deviation (RSD, n=11) of ≤ 0.5%. Mean recoveries for spiked Yb(TMHD)3 ranged from 98.2% to 100.2%. Results for ten commercial lots deviated by <0.3% from the gravimetric reference, while the total analysis time was reduced from 6 h to 15 min.
Conclusions The procedure is accurate, precise, inexpensive and field-robust, enabling on-site monitoring of Yb loading and immediate optimisation of preform deposition parameters.
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