Inorganic solvent systems for lanthanide ions

Coleman, A.P. and Rutt, H.N. (1996) Inorganic solvent systems for lanthanide ions. Optical Materials, 5 (3), 221-231. (doi:10.1016/0925-3467(95)00062-3).

Record type: Article

Abstract

Lanthanide ions dissolved in low vibrational frequency inorganic liquids have potential applications in laser systems requiring long non radiative lifetimes such as mid infrared and up conversion lasers. The use of liquids, whilst presenting some thermal and technological problems, avoids costly crystal growth and fabrication and gives great flexibility in varying lanthanide species, doping levels and co-doping. We report an extensive study of solvent systems based on POCl₃, PSCl₃, PBr₃, PCl₃, AsCl₃, SbCl₃ and SbBr₃. The relatively well known POCl₃ system is found to show a far more complex behaviour than the early literature suggests because of formation of the adduct 2POCl₃:SnCl₄. The other species except for PBr₃ and PCl₃ prove unsuitable owing to the ready production of absorbing species. PBr₃ and PCl₃ produce solvent systems when combined with the Lewis acids AlBr₃ and SbBr₃ or AlCl₃ and SbCl₃ respectively. The energy levels of all laser relevant lanthanide ions below ~ 20000 /cm were determined in the PBr₃ solvent system, and correlations between the required Lewis acid concentration and the lanthanide element found. Comparison of the spectra in various solvents leads to preliminary conclusions about the lanthanide ion coordination.