Lnohco <sub> 3 </ Sub> (ln = La, Sm, Pr), Zn <sub> 2 </ Sub> (oh) Po <sub> 4 </ Sub> Crystals By Hydrothermal Synthesis And Characterization

The theory of nonlinear optical crystals is based on the nonlinear optics. The Nonlinear optical crystal has a series of advantages which the available inorganic materials do not have, such as high coefficient of nonlinear optical, fast response, small damage performance of Anti-laser and so on. Thus in the development of optoelectronic technology which take the light as information carrier, it can carry out high speed, high density and multiple parallel processing of information. Therefore, the nonlinear optical crystal has wide application prospect and important strategic significance in the optical technology, optical information storage, integrated optics and optical communications.There are a variety of methods for artificial crystal preparation,for example, solution method, flux method ,hydrothermal method. In this paper, A series of the rare-earth carbonates LnOHCO₃(Ln=La,Sm,Pr),Tarbuttite hydroxyphosphate Zn₂(OH)PO₄ with different morphologies have been synthesized by hydrothermal method and by applying various characterizing methods, such as XRD, TEM, SEM, TGA. Some experiment is discussed on the reaction mechanism. This paper mainly includes the following several parts:1 The hydrothermal synthesis of rare-earth carbonates was studied systematically and the frequency-doubled effect of SmOHCO₃ and PrOHCO₃ was found for the first time. This experiment studied the reaction of temperature, time, pH value to the product in detail and tried to use different surfactants to control the morphology of the product, then the products were characterized by XRD,SEM,TG and so on. Thus the optimal reaction conditions were determined and micron-sized LaOHCO₃, SmOHCO₃, PrOHCO₃ crystals were synthesized successfully. Which becomes the basis of the growth of large single crystal LaOHCO₃,SmOHCO₃,PrOHCO₃ by hydrothermal synthesis.2 Tarbuttite hydroxyphosphate Zn₂(OH)PO₄is a kind of rare mineral in the nature. In this study, Zn₂(OH)PO₄ was prepared by hydrothermal synthesis, and then it was tested and proved that it had SHG. Studies show that pH value has an important effect on the purity of product. Added H₃BO₃ to properly adjust the pH value and added different surfactants to obtain different morphology of products, synthesized nanocrystalline successfully. The products were characterized by XRD,SEM,TG.at the same time.