Time dependence of photorefractive light scattering (PLS) and combinational light scattering (CS) spectra for series of congruent composition lithium niobate single crystals (LiNbO₃) doped with «nonphotorefractive» cations Gd³⁺ (С_Gd = 0,002.0,44 wt. %.) have been. It is established that for the test doping impurity concentration range PLS is most expressed at Gd³⁺ concentration of 0,003 wt. %. Thus growth of Gd³⁺ concentration significantly changes the intensity of those lines in the combinational light scattering spectrum that are forbidden by the selection rules in the scattering geometries studied in the absence of photorefraction. And, with a growth in the Gd³⁺ concentration, the intensity of the «forbidden» lines first decreases (at the concentration Gd³⁺ = 0,002.0,003 wt. %), and then significantly increases. The reduction in the intensity of the «forbidden» lines testifies to downturn of photorefraction. The decrease of the photorefractive effect can be connected with an increase in the degree of ordering in the structural units of the cation lattice along a polar axis and the related reduction in the quantities of defects with localized electrons that control photorefraction intensity.

1. Maksimenko, V. A. Fotoinducirovannye processy v kristallah niobata litija / V. A. Maksimenko, A. V. Sjuj, Ju. M. Karpec. - M. : Fizmatlit, 2008. - 96 p.
2. Sidorov, N. V. Niobat litija: defekty, fotorefrakcija, kolebatel'nyj spektr, poljaritony / N. V. Sidorov, T. R. Volk, B. N. Mavrin, V. T. Kalinnikov - M. : Nauka, 2003. - 256 p.
3. Volk, T. Lithium niobate. Defects, photorefraction and ferroelectric switching / T. Volk, M. Wohlecke - Berlin : Springer, 2008. - 250 p.
4. Sturman, B. I. Fotogal'vanicheskij jeffekt v sredah bez centra simmetrii i rodstvennye javlenija / B. I. Sturman, V. M. Fridkin - M. : Nauka, 1992. - 208 p.
5. Blistanov, A. A. Rekombinacionnye processy v kristallah LiNbO₃ / A. A. Blistanov, V. M. Ljubchenko, A. N. Gorjunova // Kristallografija. - 1998. - Vol. 43, N 1. - P. 86—91.
6. Sidorov, N. V. Navedennaja lazernym izlucheniem podreshetka mikro- i nanostruktur v fotorefraktivnom monokristalle niobata litija / N. V. Sidorov, A. A. Janichev, P. G. Chufyrev, B. N. Mavrin, M. N. Palatnikov, V. T. Kalinnikov // Dokl. RAN. - 2009. - Vol. 428, N 4. - P. 492—495.
7. Goulkov, M. Photorefractive parameters of lithium niobate crystals from photoinduced light scattering / M. Goulkov, M. Imlau, Th. Woleke // Phys. Rev. B. - 2008. - V. 77. - P. 235110—235115.
8. Kratzig, E. Photorefractive materials and their applications / E. Kratzig, O. Schirmer // Topic in Appl. Phys. - Berlin; Heidelberg : Springer Verlag, 1989. - V. 62. - P. 131.
9. Gunter, P. Photorefractive materials and their applications / P. Gunter, J. P. Huignard // Topics in Appl. Phys. - Berlin; Heidelberg : Springer, 1988. - V. 61. - P. 67.
10. Petrov, M. P. Photorefractive crystals in coherent optical systems / M. P. Petrov, S. I. Stepanov, A. V. Khomenko - Berlin : Springer, 1991. - P. 147.
11. Kuz'minov, Ju. S. Jelektroopticheskij i nelinejno-opticheskij kristall niobata litija / Ju. S. Kuz'minov - M. : Nauka, 1987. - 264 p.
12. Gurzadjan, G. G. Nelinejno-opticheskie kristally. Svojstva i primenenie v kvantovoj jelektronike / G. G. Gurzadjan, V. G. Dmitriev, D. N. Nikogosjan - M. : Radio i svjaz', 1991. - 160 p.
13. Birjukova, I. V. Vysokotemperaturnyj sintez i modifikacija svojstv segnetojelektricheskih monokristallov i shihty niobata i tantalata litija / I. V. Birjukova // Diss. … kand. Teh. nauk. - Apatity: IHTRJeMS KNC RAN, 2005. - 132 p.
14. Palatnikov, M. N. Uporjadochenie struktury i opticheskie harakteristiki legirovannyh monokristallov niobata litija / M. N. Palatnikov, N. V. Sidorov, I. V. Birjukova, P. G. Chufyrev, V. T. Kalinnikov // Perspektivnye materialy. - 2003. - N 4. - P. 48—54.