Structural phase transformations of proton-exchanged layers of lithium niobate during annealing

ABSTRACT

Kinetics of phase transitions in the surface layer of proton-exchanged planar waveguides on X-cut of lithium niobate crystal during annealing at 330, 350, and 370°C was investigated by optical methods (dark field microscopy, crossed-polarizers bright field microscopy, and mode spectroscopy). Nucleation and growth stages of phase transformations were identified. Based on mode spectroscopy data and analysis of previous works, we assume that transformation of κ₂-phase into κ₁-phase and further transformation into α-phase were observed during experiment.

KEYWORDS:

• Lithium niobate
• proton exchange
• Kolmogorov-Mehl-Avrami equation

Funding

We acknowledge support of the Russian Federal Program for “Investigations on Priority Directions of Development of Scientific and Technical Complex of the Russian Federation in 2014-2020”, Project No. 14.604.21.0055, RFMEFI60414X0055.