Abstract: Crystalline characteristic of δ-LiZnPO4 was studied under using LiF as flux system.Transparent eutectic crystallization of δ-LiZnPO4 and Li4Zn(PO4)2 with size of 1-3 mm was obtained by spontaneous crystallization method.Eutectic phase composition was determined via X-ray diffraction and element analysis, and structure of δ-LiZnPO4 crystal separated from the eutectic crystal was analyzed.The results show that the δ-LiZnPO4 crystals have a non-centerosymmetrical structure, belong to the orthogonal crystal system, space group Pna21 with lattice parameter a=1.00085 nm, b=0.93900 nm, c=0.66545 nm, Z=4.Structure analysis confirms that the crystal consists of PO4, ZnO4 and LiO4 tetrahedron to form a zeolite structure type of ABW.The transparent pure phase δ-LiZnPO4 single crystal with size of about 10 μm was also synthesized by hydrothermal method.Powder second harmonic generation (SHG) tests show that the powder SHG effect of δ-LiZnPO4 crystal is about 1.7 times of KDP and the ultraviolet(UV) cut-off wavelength of δ-LiZnPO4 crystal is 218 nm, which indicate that δ-LiZnPO4 crystal is a promising nonlinear optical crystal in the UV region.

Key words: Crystalline characteristic of δ-LiZnPO4 was studied under using LiF as flux system.Transparent eutectic crystallization of δ-LiZnPO4 and Li4Zn(PO4)2 with size of 1-3 mm was obtained by spontaneous crystallization method.Eutectic phase composition was determined via X-ray diffraction and element analysis, and structure of δ-LiZnPO4 crystal separated from the eutectic crystal was analyzed.The results show that the δ-LiZnPO4 crystals have a non-centerosymmetrical structure, belong to the orthogonal crystal system, space group Pna21 with lattice parameter a=1.00085 nm, b=0.93900 nm, c=0.66545 nm, Z=4.Structure analysis confirms that the crystal consists of PO4, ZnO4 and LiO4 tetrahedron to form a zeolite structure type of ABW.The transparent pure phase δ-LiZnPO4 single crystal with size of about 10 μm was also synthesized by hydrothermal method.Powder second harmonic generation (SHG) tests show that the powder SHG effect of δ-LiZnPO4 crystal is about 1.7 times of KDP and the ultraviolet(UV) cut-off wavelength of δ-LiZnPO4 crystal is 218 nm, which indicate that δ-LiZnPO4 crystal is a promising nonlinear optical crystal in the UV region.