The present invention relates to a
barium tetraborate compound and a
barium tetraborate non-linear optical
crystal, and a preparation method and use thereof, wherein the chemical formulae of the
barium tetraborate compound and the non-linear optical
crystal thereof are both BaB4O7, with a molecular weight of 292.58; the
barium tetraborate non-linear optical
crystal has a non-centrosymmetric structure, which belongs to a hexagonal
system, and has a
space group P65 and lattice parameters of a=6.7233(6) Å, c=18.776(4) Å, V=735.01(17) Å3, and Z=6, wherein the
powder frequency-doubled effect thereof is two times that of KDP (KH2PO4), and the
ultraviolet cut-off edge is lower than 170 nm. The
barium tetraborate compound is synthesized by a
solid-
phase reaction method; the
barium tetraborate non-linear optical crystal is grown by a high-temperature molten solution method; and the crystal has a moderate mechanical
hardness, is easy to
cut, polish and store, and is widely applicable in the non-
linear optics of a double-frequency doubling generator, an upper frequency converter, a lower frequency converter or an optical parameter oscillator etc.