Abstract
Lithium niobate, LiNbO3 (LN), is widely used as a material for electro-optical devices. The process of formation of wave-guides in LN is usually performed by the high-temperature diffusion of some element, usually Ti, previously patterned by conventional photolithography techniques on LN substrate. As a result of the process, shallow surface patterns of higher refraction index (wave-guides) are formed on the LN single crystal. The characteristics of the obtained wave-guides, including optical stability and power losses, depend mainly on the sizes of the diffusion zones, their contour and concentration profiles of the components in the zones. The composition of the gas phase has an appreciable influence on the diffusion process. This is related to the influence of the gas environment on the balance of defects in the sub-surface zone of LN and, hence, on its kinetic characteristics. Thus, the elucidation of the mechanism of interaction of the crystal surface layer with gas phases of various compositions at high txemperatures is of considerable interest for the development of optimal technologies of electro-optical devices. At the same time, no data are available in the literature relevant to the equilibrium of LN with gas phases of various compositions at the temperatures usually used in the diffusion process. In this paper we present some results that may be useful for the understanding of the parameters involved. A computer modeling of the equilibrium in LN-gas phase systems was carried out with calculations for the following gas phases: (a) inert gas (Ar) or vacuum with LN, (b) oxygen, and (c) a mixture of oxygen with water vapor. The modeling of equilibrium was carried out using the “Astra-4” code [1]. The code algorithm is based on the maximization of the system entropy by the iteration method. Thermo-chemical data for LiNbO3 were taken from the literature [2–4]. No data were found for the thermo-chemical characteristics of LiNb3O8. This phase is conjugated with LiNbO3 in quasi-binary Li2ONb2O5 system. Besides, we have not found in the literature the thermo-chemical characteristics of LiNbO3 within its homogeneity range. Obviously, the published data [2] concern LN stoichiometric composition. Thus, two possibilities arise:
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
