The invention provides a preparation method of a wide-band-gap optical
crystal sodium potassium fluosilicate and application of the wide-band-gap optical
crystal sodium potassium fluosilicate in a deep
ultraviolet optical window device. The
chemical formula of the
sodium potassium fluosilicate
crystal is KNaSiF6, the crystal has a symmetric center and belongs to an
orthorhombic crystal system, the
space group is Pnma, the
cell parameters are # imgabs 0 # beta = 90 degrees, gamma = 90 degrees, Z = 4, and the unit
cell volume is # imgabs 1 #. The sodium potassium fluosilicate broad-
band gap optical crystal with the size larger than 2.67 * 1.04 * 1.02 mm < 3 > can be obtained by adopting a hydrothermal cation replacement
crystallization method for growth; the
potassium sodium fluosilicate crystal with a larger size can be obtained by using a higher growth temperature, replacing a larger
crystallization space, prolonging the
crystallization time and the like, and the method is green, environment-friendly, low in cost, high in yield, high in quality of the grown
single crystal, large in size and suitable for large-scale production. The
potassium sodium fluosilicate crystal has a theoretical
band gap of 10.11 eV, corresponds to a deep
ultraviolet cut-off
absorption edge of 123 nm, is suitable for deep
ultraviolet optical window devices, is suitable for optical window devices with the
wavelength of 123-3500 nm in a
light transmission band, and is especially suitable for deep ultraviolet optical window devices with the
wavelength of 123-200 nm.