Study Of Mixed Alkali Metal Borate UV Nonlinear Optical Crystals And The System Expansion

Ultraviolet laser has a wide range of applications in the fields of lithography,high-resolution spectroscopy,laser cooling and so on.Frequency conversion of laser light by nonlinear optical(NLO)crystals is the best method to generate UV coherent light by solid-state lasers.In this thesis,we aim to design and synthesize new UV nonlinear optical materials based on the study of mixed alkali metal borates,and synthesize seven novel compounds in this system,while expanding the system to silicates and synthesizing three new compounds,and their structures and properties were systematically characterized1.Design,synthesis and characterization of LiK0.52Cs0.48B6O10 ? Li4CsRb2B7O14Based on the classical CLBO structural model,we synthesized novel mixed alkali metal borates that LiK0.52Cs0.48B6O10 and Li4CsRb2B7O14 by single substitution of Cs+.The single crystal structure analysis shows that LiK0.52Cs0.48B6O10 crystals belong to the tetragonal crystal system with space group I42 d and the cell parameters of a=10.4286(7)A,c=9.1968(13)A,which the structure is isomorphic to CLBO,and Li4CsRb2B7O14 crystals belong to the tetragonal crystal system with space group P3221 and the cell parameters of a=6.8957(4)A,c=26.3860(13)A,the isolated B7O14 as its building block and cation-filled.The SHG responses are 2.7× and 0.5× KDP,They are capable of achieving class I phase matching at 1064 nm.The UV cutoff edge of LiK0.52Cs0.48B6O10 is less than 190 nm.2.Synthesis and characterization of new mixed alkali borates containing B12O24 groupWe explore in rich boron system by mixed alkali metal.Li7Na2K3B12O24,Li7Na3M2B12O24(M=Cs,Rb)and Li9Rb2KB12O24 crystallize in the same space group R3,which is related to the local symmetry of B12O24 group.The crystal structures of these compounds are more dependent on their anionic groups.The UV cutoff edge of Li7Na2K3B12O24 is less than 190 nm.3.Design,synthesis and characterization of PbSrSiO4A new nonlinear optical material PbSrSiO4 was successfully synthesized by introducing Pb2+ ions into silicates.Due to its unique structure,the UV cut-off edge of the compound is about 240 nm and has a suitable birefringence(0.053@1064 nm).The SHG response is about 5.8×KDP.The structure subtly balances the inherent contradiction between band gap,birefringence and SHG effect,which provides a new way to synthesize UV or deep UV nonlinear optical materials4.Synthesis and characterization of Pb3[O10Pb20](SiO4)4X10(X=Cl,Br)The structure contains interesting two-dimensional(2D)[O10Pb20]20+ layers,which can be regarded as pseudo Aurivillius type layers evolved from[OPb]layers in ?-PbO.The special two-dimensional[O10Pb20]20+ layers were found in silicates for the first time,which enriches the structural chemistry of lead containing silicates.