Lithium in-diffusion treatment of thick LiNbO3 crystals by the vapor transport equilibration method

• Published in: Journal of crystal growth Vol. 260; no. 1-2; pp. 143 - 147
• Main Authors: Xinan, L, Xu, X, Chong, T-C, Yuan, S, Yu, F, Tay, Y S
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier 02.01.2004
• Subjects: Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Growth from vapor; Materials science; Methods of crystal growth; physics of crystal growth; Optical materials; Optics; Other nonlinear optical materials; photorefractive and semiconductor materials; Physics; Inorganic compounds; 81.10 A2. Vapor transport equilibration; Crystal orientation; 78.20.C; Ternary compounds; Scattering; Transition element compounds; Crystal growth from vapors; Experimental study; Thickness; Cracks; Monocrystals; Lithium niobates; B1. Lithium niobate; 42.70.Mp; 66.30; Equilibration; B2. Photorefractive materials; Absorption edge
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2003.08.015

Congruent LiNbO3 (CLN) crystals with various orientations (X-, Y- and Z-cut) and thickness (1-3.2 mm) were treated by the vapor transport equilibration (VTE) method in lithium-rich environment at 1100 deg C. Homogeneous and crack-free crystals with nearly stoichiometric composition ( > 49.9 mol% Li2O) were obtained for different orientations. The cracking problem of X- and Y-cut samples was studied and solved by decreasing the cooling rate after the VTE treatment. The Li2O content in the crystal was determined by the cutoff UV absorption edge of the crystal sample. For thick samples, the diffusion of lithium atoms from side faces had influenced the composition homogeneity of the VTE-treated crystals. The CLN crystal plates with thicknesses of around 2 mm were converted into stoichiometric LiNbO3 (SLN) by the VTE method within 200 h. Thicker CLN samples would need longer time to be converted into SLN.