Method for improving homogeneity of potassium tantalate niobate crystal through double-crucible real-time material-feeding technology

Abstract

The invention discloses a method for improving homogeneity of a potassium tantalate niobate crystal through a double-crucible real-time material-feeding technology. In the method, high-purity K2CO3, Ta2O5, Nb2O5 are employed as raw materials. A KTN polycrystal basic material and a KTN polycrystal supplying material are respectively weighted and prepared according to required crystal components. The polycrystal materials are prepared through a grinding process, a uniformly blending process, a pressing moulding process and a sintering process. According to requirements of the double-crucible real-time material-feeding technology, an internal-external double-crucible temperature field system is designed and corresponding transformation of a lifting furnace is carried out for satisfying a real-time material-supplying requirement. A crystal growing process includes following steps: a seed adding process, a necking process, a shoulder-releasing process, an equal-neck turning process and an equal-neck growing process. During the crystal growing process, a crystal growing speed and a material-supplying speed are maintained to be equal for ensuring melt components to be stable. When the crystal growth is finished, the crystal is lifted from a liquid surface and is cooled slowly to room temperature to obtain a KTN monocrystal. By means of the technical scheme, crystal component fluctuation caused by fluctuations of the melt components and a growth temperature during the KTN monocrystal growing process through a conventional melt lifting method is greatly reduced, thereby greatly improving the homogeneity of the KTN crystal. The method has an important significance on practical application of the KTN crystal.

Description

technical field [0001] The invention belongs to the research field of preparation technology of functional crystal materials, and relates to a method for improving the compositional uniformity of potassium tantalum niobate crystals by introducing double-crucible real-time feeding technology on the basis of pulling method, thereby improving the optical quality of potassium tantalum niobate crystals . Background technique [0002] The electro-optic effect is a phenomenon in which the refractive index of the medium changes under the action of an external electric field. The phase, intensity and propagation direction of light can be modulated by using the electro-optic effect of crystal materials. Electro-optic modulation is due to high efficiency, fast response and non-mechanical (no Inertia) and other advantages, usually used to make laser modulators, scanners and optical switches and other devices, widely used in laser radar, laser ranging, biomedical microscopic imaging and...

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Problems solved by technology

At present, a prominent problem that limits the application of KTN crystal electro-optical components is that it is difficult to balance the size and uniformity of the crystal. In order to obtain a large-size KTN crystal, it is necessary to increase the cooling range of the crystal growth process. In the case of constant melt quality, The larger the crystal, the greater the change of the melt composition, both of which will in turn affect the fluctuation of the crystal composition, forming stripe defects, resulting in the scattering of the laser spot during light modulation, especially in the case of long optical path and large beam diameter. In some cases, it is difficult to obtain a satisfactory modulation effect

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