Study On Some Monoclinic Double Tungstate Crystal Growth And Characterization

Optical maser plays more and more important role in our daily life, especially for the wide applications of the blue, green and ultraviolet (UV) laser in industry and medicine. Tungstate crystal is a family which has been studied for a long time, and the Nd:CaWO₄ is one type of the first crystal realized laser operation. Double tungstate crystals show different structures and crystallization habits according to the alkali ions. KRe(WO₄)₂ (Re is rare earth element) belongs to monoclinic system, space group C2/c. Many new characteristics in their performance are found in these crystals due to their strong anisotropy structure. In our work, the growth and performance characteristic of the monoclinic KReW were studied, in which the primary coverage is as follows,(1) Crystal growth is the base of other further research. Many high optical quality KRe(WO₄)₂ crystals with large sizes have been successfully grown. These crystals are Er:KLuW, Sm:KLuW, Tm:KLuW, Dy:KLuW, Ho:KLuW, Er:Yb:KLuW, Ho,Yb:KLuW and Cr³⁺, Nd:KYbW. Additionally, some rare reported crystals such as RbGd(WO₄)₂ and NaLuW have also been successfully obtained.(2) The structure, growth morphologies and the optimal growth technic of KReW crystals.The structure of RGW, KLuW, NaLuW crystals have been solved by fore four-circle diffractometer and the structure of the various rare earth ions doped KLuW crystals have been solved by powder diffraction method. The ideal morphologies of the crystals have been predicted by BDFH, Wolff, PBC theories and compared to the real growth morphologies. Though these studies we obtained the optimum growth directions and cooling rate.(3) The investigation of the growth mechanisms and the defects of KLuW crystals.Growth mechanisms on the {110} and {310} faces of KLu(WO₄)₂ crystals for the case of top-seeded solution growth technique have been investigated using ex situ atomic force microscopy (AFM). Both 2D nuclei and spiral hillocks are imaged simultaneously on the {110} surfaces. A special dislocation sources structure with the...