Journal of Crystal Growth, Vol.264, No.1-3, 339-345, 2004
Crystal growth and characterization of titanium-doped near-stoichiometric LiNbO3
Titanium-doped near-stoichiometric LiNbO3 (SLN) crystals were grown from lithium-rich solutions with a Ti concentration of up to approximately 20mol% by a top-seeded solution-growth (TSSG) method. Ti-doped SLN (Ti:SLN) crystals with a Ti concentration of up to 9 mol% were free from inclusions, voids, cracks, or mechanical twins. The effective distribution coefficient k(eff) for Ti in the Ti:SLN crystals was found to be approximately 0.45 +/- 0.05 for the Nb atom in the above composition range. The Ti-doping effects on Curie temperature, UV absorption edge, changes in the ordinary and extraordinary refractive indexes (Deltan(o) and Deltan(c)) and lattice constants were investigated. The Curie temperature for the Ti:SLN crystals linearly decreased with increasing Ti concentration up to 9mol%. Both Deltan(o) and Deltan(e) linearly increased with increasing Ti concentration up to 9 mol%, and Deltan(e) was much larger than Deltan(o) over the entire wavelength range from 440 to 1550 nm. The UV absorption edge for the Ti:SLN crystals shifted to longer wavelengths with increasing Ti concentration. The a- and c-axes lattice constants in the Ti:SLN crystals decreased with increasing Ti concentration. In addition, a photoelastic effect on the refractive-index changes in the Ti:SLN crystal was estimated from the lattice-constant data. (C) 2004 Elsevier B.V. All rights reserved.
Keywords:characterization;growth from solutions;top seeded solution growth;oxides;ferro-electric materials;nonlinear optical materials;nonlinear optical