Abstract: The crystal of K₃Dy(PO₄)₂ has been grown from KCl-KF melt.A single crystal in size of 1.5?1.2?0.5mm³ was obtained under certain ratio of rare-earths to flux and by proper controlling the quantity of volatilization.The composition K₃Dy(PO₄)₂ was identified by chemical analysis.X-ray diffractometry proved that the crystal belongs to monoclinic system with space group P2₁/m.The lattice parameters of the crystal were calculated. It is found that the cell volume of crystal reduces as the atomic number of rare earth in K₃Ln(Po₄)₂ increases, ion radius of Ln³⁺ decreaces and the complex ability increases. The infrared,absorption,excition,and fluorescene spectra of K₃Dy(PO₄)₂ are also reported.

Key words: Crytal growth, Potassium dysprosium diphosphate, Lattice paramters, Spectra of crystal