Photoelectricity And Electron-transfer Research Of Lithium Niobate

Lithium Niobate (LiNbO₃: LN for short) is one of the very important multifunctional crystals. It possesses excellent piezoelectricity, nonlinear-optics, electro-optics, and photo-refractive capacity and so on. In 1965, S A Fedulov of Russia and A A Ballman of America had successfully growth single LiNbO₃ crystal by Czochralski method. After that, most researches were carried on LiNbO₃ crystal. Nearly half century, people are interested in its grown token and applications. Because of its multi- properties, it has being widely applied in nonlinear-optics, photoelectron technique, communication and optic data storage domain.After Chen etc. realized holographic data storage on LiNbO₃ crystal in 1968, this crystal had being widely investigated and applied in optic holographic data storage. Until now many holographic fixing methods have being brought forward, the master ones are thermal fixing, electrical fixing and optical fixing. The last one can store steady, permanent, and especially repeated reading non-damage holograph. So more attentions are paid to optical fixing method.Use optical fixing method first needs to know micro phenomenon of electron transfer in light irradiation of LiNbO₃, and establish corresponding electron transfer model. At present many researches are concentrated on impure LiNbO₃ crystal, and few studies are taken on the pure crystal, and relevant theoretical model is missing.According to this matter, this article discusses the electron transfer of LiNbO₃ crystal, studies the light-induced absorption of LiNbO₃:Fe, and experimentally studies the dark conductivity of pure LiNbO₃. The main work includes:1. Comparatively analyses various disfigurement model of LiNbO₃ crystal, and chooses Li vacancy model as the base of this study.2. Discusses the photoelectric phenomena and relevant micro electron transfer model of LiNbO₃ crystal, including typical LN: Fe and pure LiNbO₃ crystals. The photoelectric phenomena main involves: light absorption, light-induced absorption, light conductivity, and dark conductivity. In this article more attention are paid to light- induced absorption and dark conductivity.3 . Experimental research: Analysis the results of other people's research of LiNbO₃:Fe, and experimentally study the dark conductivity of pure LiNbO₃.The pure crystal samples include congruent LiNbO₃, near-stoichiometric LiNbO₃, and non-stoichiometric LiNbO₃, find the relation of dark conductivity and [Li]/[Nb] ratio。Otherwise analysis the relation of dark conductivity and temperature of pure crystal in other literature.4. Combine the experimental results and theory analyses, we find that the electron transfer and photoelectric phenomena are related to the [Li]/[Nb] ratio. In LN:Fe crystal the concentration of Fe also affects them.