EPR and optical properties of La3Ga5.5Ta0.5O14:Co2+ single crystals

H. Fuks; S. M. Kaczmarek; M. Berkowski

doi:10.1117/12.622506

11 October 2005 EPR and optical properties of La₃Ga_5.5Ta_0.5O₁₄:Co²⁺ single crystals

H. Fuks, S. M. Kaczmarek, M. Berkowski

Proceedings Volume 5958, Lasers and Applications; 595826 (2005) https://doi.org/10.1117/12.622506
Event: Congress on Optics and Optoelectronics, 2005, Warsaw, Poland

Abstract

Cobalt doped La₃Ga_5.5Ta_0.5O₁₄ single crystal (0.5 mol.% in the melt with respect to Ga) grown by the Czochralski method has been investigated using electron paramagnetic resonance and optical absorption measurements. X- band EPR spectra observed at 8 K under rotation around c crystal axis consists of two asymmetric lines: a narrow line at ~150 mT magnetic field and a second wider line at ~350 mT. These lines could be ascribed to the high spin S=3/2 Co²⁺ ions located at two different crystallographic positions. The low field signal arises from cobalt occupying Ga positions with C₃ symmetry (octaheder), whereas dominating in spectrum, more complicated signal at higher fields arises from cobalt located at Ga positions (tetraheder) with C₂ point symmetry. The whole spectrum repeats every 60° as is expected for trigonal crystal symmetry. Optical measurements have confirmed the conclusion especially for γ-irradiated crystals which reveal additional Co³⁺ content after the treatment. Co³⁺ ions are also seen in "as-grown" (not irradiated) crystals as ⁵T₂-⁵E transition giving absorption bands in the range 700-1100 nm. So in the "as-grown" crystals there arise Co²⁺ ions at octahedral or tetrahedral Ga sites and Co³⁺ ions at octahedral Ga sites.

Citation Download Citation

H. Fuks, S. M. Kaczmarek, and M. Berkowski "EPR and optical properties of La₃Ga_5.5Ta_0.5O₁₄:Co²⁺ single crystals", Proc. SPIE 5958, Lasers and Applications, 595826 (11 October 2005); https://doi.org/10.1117/12.622506

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