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Growth and characterization of Li2B4O7 single crystals pure and doped with Co ions

Danuta Piwowarska 1Sławomir Kaczmarek 1Marek Berkowski 2Ireneusz Stefaniuk 3

1. Szczecin University of Technology, Institute of Physics, Al. Piastów 48/49, Szczecin 70-311, Poland
2. Polish Academy of Sciences, Institute of Physics, al. Lotników 32/46, Warszawa 02-668, Poland
3. University of Rzeszow, Rejtana 16 A, Rzeszów 35-310, Poland


The paper reports on the growth conditions of Li2B4O7 single crystals in both pure and Co doped ions. The crystals were grown by the Czochralski method at a growth rate of 0.6 mm/h and rotation rate 5.0 rpm in the Institute of Physics, Szczecin University of Technology, Poland. Technological factors affecting the quality of the crystals, both pure and doped, have been discussed. As raw materials boric oxide (B2O3), lithium bicarbonate (Li2CO3) and dopant ions (Co) in the form of oxides of purity 4N and 5N were used. The growth processes were carried out without protective atmosphere (in the presence of oxygen), with the use of platinum crucible, 50 mm in diameter and height. The optimum initial composition of melt has been defined, which is dependent on the speed of boric oxide evaporation reaching 90 mg/h. A schematic phase diagram of this solution is proposed. Starting concentrations of Co in the melt were: 0.5, 0.85 and 1 mol. % with respect to Li2CO3. Absorption and EPR spectra were analyzed with the aim of define of oxidation state and site of cobalt ions. Optical measurements show that Co-doped Li2B4O7 exhibit distinct absorption bands near 500, 1100 and 1500 nm associated with electronic transitions characteristic of Co2+ ions at octahedral Li+ site positions. Low-temperature EPR measurements show that in the Li2B4O7:Co crystal two types of Co2+ complexes can be distinguished. Obtained single crystals Li2B4O7 has been used in the processing system on the second harmonic generation of laser YAG:Nd.


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Presentation: Poster at Joint Fith International Conference on Solid State Crystals & Eighth Polish Conference on Crystal Growth, by Danuta Piwowarska
See On-line Journal of Joint Fith International Conference on Solid State Crystals & Eighth Polish Conference on Crystal Growth

Submitted: 2007-01-15 01:35
Revised:   2009-06-07 00:44