Preparation method with component controllability and directional crystallization for near-stoichiometric lithium niobate (N-SLN) crystal

Abstract

The invention discloses a preparation method with component controllability and directional crystallization for a near-stoichiometric lithium niobate (N-SLN) crystal. A low temperature area, a high temperature, a temperature gradient area and a heat preservation area are formed in a hearth of a single crystal furnace in sequence, and a crucible successively passes through the four temperature areas. The preparation method successively comprises the following specific steps of 1, pre-crystallization material preparation: preparing two mixtures A and B formed by Li2CO3 and Nb2O5, wherein the molar ratio of Li / Nb in the mixture A is 1 to 1, and the molar ratio of Li / Nb in the mixture B is between 1 to 1 and 58.5 to 41.5; 2, furnace charging: putting lithium niobate seed crystal into a seed crystal groove of the crucible, a pre-crystallization material B is put on the shoulder of the crucible, a pre-crystallization material A is put on the monospaced part of the crucible; 3, material melting; 4, crystal seeding; 5, diameter enlarging; 6, monospaced growing; 7, ending; 8, annealing and cooling. An N-SLN crystal prepared by the method has the advantages that the size is large, the quality is high, the content of Li is uniform, energy consumption is low, the repeatability is high and the like, and the large scale production is easily realized.

Description

technical field [0001] The invention relates to near-stoichiometric lithium niobate (N-SLN for short) crystals, in particular to a method for preparing N-SLN crystals with controllable directional crystallization, belonging to the technical field of crystal growth. Background technique [0002] Lithium niobate crystal is a multifunctional crystal material integrating piezoelectric, ferroelectric, pyroelectric, nonlinear, electro-optic, photoelastic, photorefractive and other functions. At present, it has been used in infrared detectors, laser modulators, optical communication modulators, optical switches, optical parametric oscillations, integrated optical components, high-frequency broadband filters, narrow-band filters, high-frequency high-temperature transducers, microacoustic devices, lasers, etc. Frequency multipliers, holographic storage, and optical waveguides have been widely used in practical applications. However, although the commonly used lithium niobate (CLN)...

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Problems solved by technology

Although this method is currently the best method for growing large-sized N-SLN crystals, it still has the following disadvantages: First, because the inner and outer crucibles are only connected by small holes at the bottom, the melts in the inner and outer crucibles cannot be fully mixed, resulting in crystal composition It is not completely uniform; second, the melt flowing from the outer crucible to the inner crucible carries heat and mass, and its symmetry is poor, which will increase the instability of the temperature field of the inner crucible; third, it is difficult for the continuous feeding device to accurately replenish the required feedstock, which is affected by fluctuations in feedstock particle size, uniformity, and actual growth rate

Although the continuous feeding double crucible method has been invented for more than 20 years, it still remains in the laboratory stage and has not achieved large-scale industrial production

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