RADIATION-INDUCED DEFECTS AND DICHROISM IN La3Ga5,5Ta0,5O14 CRYSTALS
Nina Kozlova, Oleg Buzanov, Anna Kozlova, Evgeniia Zabelina, Vladimir Shayapov, Nikita Siminel
Received: 29 FEB 2016,
Received revised: 20 APR 2016,
Accepted: 26 APR 2016,
Published online: 26 DEC 2016
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We investigated the transmission spectra of the langatate (LGT, La3Ga5,5Ta0,5O14) crystals grown in different conditions (crucible – Ir or Pt, growth atmosphere – air, pure Ar, Ar with addition of oxygen 2% or less then 2%), in the initial state and after electron irradiation. We observed dichroism in these crystals. Dichroism indicates the anisotropy of defect centers. We obtained the dependence of transmission on the irradiation dose and found that electron irradiation causes a decrease of transmission in the wavelength range 250-700 nm. On the transmission spectra in the infrared region, we observed oscillations, which can presumably refer to the formation of a layered structure as a result of irradiation. We have calculated the thickness of the formed layer. Luminescent characteristics of LGT crystals depend on growth conditions. Intensity of luminescence in LGT (Ar+(2%)O2) is lower than in LGT (Ar). Electron irradiation leads to the reduction of intensity. The observed luminescence in langatate crystals is provided by different luminescent centers.
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