Crystal Synthesis,Structure And Performance Study Of Metal Phosphates With Stereochemical Active Lone Pair

As one of the most important inventions of the 20th century,laser gets quite a wi de range of applications in the present military and every field of life,such as remote of precision-guided weapons,space wireless communication,laser show in stage perf ormances,laser cosmetic instrument,laser lithography,etc.The application of laser in these areas involves different frequency from deep ultraviolet to the far-infrared.As a n important part of all-solid-state laser device,nonlinear optical crystal plays a key rol-e in laser frequency conversion.Phosphate crystals have become another hotspot in r ecent years due to their large band gap,rich structural chemistry and application prosp ect in deep ultraviolet field.This paper mainly studied that the introduction of lead cat ions and bismuth cations with stereochemically active lone electron pairs in phosphate system,improved and adjusted the properties and structure of phosphate,and success fully synthesized five new metal phosphates containing lone electron pair cations,the specific results are as follows:1.Synthesis,structure and properties of lead phosphate nonlinear optical crystalsTwo lead phosphate compounds Li₂Sr_0.52Pb_1.48P₂O₈ and Li_0.34Zn_0.83Sr Pb P₂O₈ wit-h non-centrosymmetric structure have been synthesized by introducing lead cations with stereochemically active lone electron pairs into the phosphate system.Both of th em crystallize in the polar orthorhombic space group Pna2₁.In their structures,lithiu m/zinc-oxygen tetrahedrons and phospho-oxygen tetrahedrons are interconnected to f orm a three-dimensional network,then lead cations and strontium cations fill the gaps in the network.The lithium oxygen tetrahedrons and phosphorus-oxygen tetrahedron-s in the structures of both of them show great distortion.The dipole moment calculati on shows that the SHG effect of the two compounds is contributed by the lead oxygen polyhedron with stereochemically active lone electron pairs.As for properties,Li₂Sr_0.52Pb_1.48P₂O₈ has a large SHG effect（2.92×KDP）and a short ultraviolet cutoff edge（275nm）,and the existence of[PO₄]^3-group in the structure has been proved by infrared spectra.The results of thermogravity-differential scanning calorimetry（TG-DSC）an d powder X-ray diffraction（XRD）showed that it had good chemical stability at room temperature to 1000℃and was uniformly fused.2.Synthesis,structure and characterization of bismuth phosphate complexing alkaline metal/alkaline earth metalBismuth cations with stereochemically active lone electron pairs are introduced into the phosphate system,two bismuth phosphate compounds K₂Sr Bi₂(PO₄)2（P₂O₇）and K₂Ca_0.70Bi_2.20（PO₄）₂（P₂O₇）and one phosphate with high polymerization degree of bismuth oxygen group([Bi₃O₁₃]^15-)compound Na Rb Bi₃P₃O₁₃ were successfully synthesized,and then based on the ratio of alkali/alkaline earth metal ions to bismuth and phosphorus,in-depth study of this phenomenon was discussed,enrich the structural chemistry of phosphate.Besides,we also have found a non-centrosymmetric bismuth phosphate compound:Bi₃₂Cd₃P₁₀O₇₆ and XRD pattern suggests it melts congruently.