Volume 1, Issue 3 (December 2016)

Original research papers

Radiation Physics

RADIATION-INDUCED DEFECTS AND DICHROISM IN La3Ga5,5Ta0,5O14 CRYSTALS

Nina Kozlova, Oleg Buzanov, Anna Kozlova, Evgeniia Zabelina, Vladimir Shayapov, Nikita Siminel

Pages: 171-176

DOI: 10.21175/RadJ.2016.03.032

Received: 29 FEB 2016, Received revised: 20 APR 2016, Accepted: 26 APR 2016, Published online: 26 DEC 2016

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.
  1. N. S. Kozlova, O. A. Buzanov, E. V. Zabelina, A. P. Kozlova, M. B. Bykova, “Point defects and dichroism in langasite and langatate crystals,” Cryst. Reports vol. 61, no. 2, pp. 275-284, 2016.
    DOI: 10.1134/S1063774516020103
  2. G. M. Kuz’micheva et al., “The color of langatate crystals and its relationship with composition and optical properties,” Cryst. Res. Technol., vol. 47, no 2, pp. 131-138, 2012.
    DOI: 10.1002/crat.201100356
  3. H. Kimura, S. Uda, O. Buzanov, X. Huang and S. Koh, “The effect of growth atmosphere and Ir contamination on electric properties of La3Ta0.5Ga5.5O14 single crystal grown by the floating zone and Czochralski method,” J. Electroceram, vol. 20, no 2, pp. 73-80, 2008.
    DOI: 10.1007/s10832-007-9349-2
  4. G. J. Dienes and G. H. Vineyard, Radiation effects in solids, Interscience Publishers, New York, 1957.
  5. S. T. Konobievskiy, Influence of irradiation on materials, Atomizdat , Moscow, 1967. (in Russian).
  6. L. Velluz, M. Legrand and M. Grosjean, Optical circular dichroism: principles, measurements, and applications, New York, 1965.
  7. T. Tudor, V. Manea, “Symmetry between partially polarized light and partial polarizers in the vectorial Pauli algebraic formalism,” J. Mod. Opt., vol. 58, no 10, pp. 845-852, 2011.
    DOI: 10.1080/09500340.2011.575960
  8. K. A. Kaldybaev, A. F. Konstantinova and Z. B. Perekalin, Gyrotropy of uniaxial absorbing crystals, Institute of socio-economic and industrial-ecological problems of investment, Moscow, 2000. (in Russian).
  9. B. M. Ayupov, Yu. M. Rumyantsev and V. R. Shayapov, “Features of determination of thickness of dielectric films obtained in searching experiments,” J. of Surface Investigation. X-ray, Synchrotron and Neutron Techniques, vol. 4, no. 3, pp 452-457, 2010.
    DOI: 10.1134/S1027451010030158
  10. J. Stade, L. Bohaty, M. Hengst, R.B. Heimann, “Electro-optic, piezoelectric and dielectric properties of langasite (La3Ga5SiO14), langanite (La3Ga5,5Nb0,5O14) and langataite (La3Ga5,5Ta0,5O14),” Cryst. Res. Technol., vol. 37, no. 10, pp. 1113 – 1120, 2002.
    DOI: 10.1002/1521-4079(200210)37
  11. K. Kanaya and S. Okayma, “Penetration and energy-loss theory of electrons in solid targets,” J. Phys. D: Appl. Phys., vol. 5, no 43, pp. 43-57, 1972.
  12. D.C. Malocha et al., “Recent Measurements of Material Constants versus Temperature for Lagatate, Langanite and Laтgasite,” in Proc. 2000 IEEE/EIA Int. Freq. Control Symposium and Exhibition, 2000, pp 200-205.