Compound sodium lithium aluminum fluoride borate and sodium lithium aluminum fluoride borate birefringent crystal as well as preparation method and application of compound sodium lithium aluminum fluoride borate birefringent crystal

Abstract

The invention relates to a compound lithium sodium fluoroaluminoborate, a lithium sodium fluoroaluminoborate birefringent crystal, a preparation method and an application of the lithium sodium fluoroaluminoborate birefringent crystal. The chemical formula of the compound is LixNa (1-x) AlB2O4F2 (x = 0.4-0.6), the molecular weight of the compound is 163.96-167.17, and the compound is synthesized by adopting a vacuum tube sealing method. The chemical formula of the birefringent crystal is LixNa (1-x) AlB2O4F2 (x = 0.4-0.6), the molecular weight is 163.96-167.17, the birefringent crystal belongs to a monoclinic system, the space group is P21 / c, and the cell parameters are as follows: a = 3.6329 (3), b = 14.1750 (12), c = 8.3735 (10), V = 423.39 (7) 3 and Z = 4. The crystal is used for an infrared-deep ultraviolet band and is a biaxial crystal, and the transmission range is 200 nm to 3 microns; and the birefringence is 0.101 (1064nm). The crystal is prepared by adopting a vacuum tube sealing method, and the method has the advantages of simplicity in preparation, short growth cycle, low toxicity of used starting raw materials, stable physical and chemical properties and the like. The method can be used for manufacturing polarization beam splitting prisms, phase delay devices, electro-optical modulators and the like.

Description

technical field [0001] The present invention relates to a birefringent crystal of lithium sodium fluoroaluminoborate and its preparation method and application, in particular to a crystal with the molecular formula Li for the infrared-deep ultraviolet band x Na (1-x) AlB 2 o 4 f 2 (x=0.4-0.6) sodium lithium fluoroaluminoborate birefringent crystal and its preparation method and application. Background technique [0002] Birefringence is one of the important characteristics of light propagating in non-uniform medium crystals. The root cause of this phenomenon is the anisotropy of crystal materials, which can be explained by the transverse wave properties of light. When light propagates in an optical heterogeneous homogeneous body (such as a crystal other than a cubic system), its vibration characteristics will be changed except for a few special directions (along the direction of the optical axis), and it will be decomposed into two electric field vector vibration directi...

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Problems solved by technology

MgF 2 It has a wide transmission range, which can reach 110-8500nm, but its birefringence is too small, it is not suitable for making Glan prisms, it can only be used for Rochon prisms, and the separation angle of light speed is small, the size of the period is large, and it is inconvenient to use; LiNbO 3 Although crystals are easy to obtain large-sized crystals, the birefringence is also small, and the same problem exists

YVO 4 It is an artificially prepared birefringent crystal with good performance, but its transmission cut-off edge is higher than 400nm, so it cannot be used in the ultraviolet region, and because YVO 4 The melting point is high, and the iridium crucible must be used for pulling growth, and the growth atmosphere is a weak oxygen atmosphere, so there is a problem of price change of the iridium element during growth, which reduces the quality of the crystal and makes it difficult to obtain high-quality crystals; α-BaB 2 o 4 It is the only commercial birefringent material with large birefringence and DUV transparency, but the crystal is easy to deliquescence, and due to the existence of solid-state phase transition, it is easy to crack during the crystal growth process; calcite in natural form is the most widely used birefringence Crystal, but it is difficult to artificially synthesize, small in size, high in impurity content and easy to dissociate, and cannot meet the requirements of large-scale optical polarizing elements. Ordinary crystals can only use the band above 350nm, and it is difficult to obtain ultraviolet optical grade calcite crystals. The use of wavelength bands cannot reach the deep ultraviolet region (<250nm)

Rutile also mainly exists in natural form, and it is difficult to synthesize artificially, and it is small in size, high in hardness, and difficult to process

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