Synthesis,Structure And Electronic Structure Calculation Of K₂BaPO₄F And Pb₆O₄?BO₃??NO₃?

With the development of laser chemistry,laser spectrum,laser medical treatment,and lithography technology,the demand for shorter wavelength and higher frequency laser becomes more urgent.Deep ultraviolet coherent materials with wavelength below 200 nm?>6.2 eV?,birefringence crystals with excellent properties have attracted great interest from both academic and technical perspectives.In this paper,different reaction systems and reaction conditions are designed for the synthesis of ultraviolet and birefringent crystal materials.A new compound K₂BaPO₄F with perovskite structure was successfullysynthesized by high temperature solid phase reaction.Single-crystal X-ray diffraction analysis reveals that it crystallizes in tetragonal,space group I4/mcm with a=7.026?1??,b=7.026?1??,c=11.279?4??,V=556.8?2??³,and Z=4.The structure consists of the A-site[PO₄]tetrahedrons groups and the BX₃ F-centered octahedral[FK₄Ba₂]groups linked together through vertices to form the perovskite framework represented by ABX₃.UV-vis-NIR spectrum shows that K₂BaPO₄F possesses a cut-off wavelength of less than 182 nm,the experimental band gap was6.16 eV.The calculated band structures and the density of states indicate that K₂BaPO₄F is an indirect band gap compound.thermal stability of K₂BaPO₄F are also reported in this work.TG-DSC showed that the compound had good thermal stability.K₂BaPO₄F is expected to be a potential UV crystal material.A borate-nitrates Pb₆O₄?BO₃??NO₃?has been successfully synthesized under thehydrothermal condition.Single-crystal X-ray diffraction analysis shows that it crystallizes in orthorhombic space group Pmmn?59?with a=5.730?4??,b=9.423?7??,c=11.246?8??,Z=2.In this structure,OPb₄ can form a chain of 1D by sharing oxygen atoms in the direction of the a axis.The Pb-O chain is interconnected with the layer of 2D between the BO₃ groups and the layers are separated by the isolated NO₃ group.It is worth noting that the NO₃ group is isolated between the layers and is not connected to any atom.IR,TG-DSC,EDS and UV-VIS diffuse reflectance were used to characterize its properties.This is the first time that Pb₆O₄?BO₃??NO₃?is used for theoretical calculations and the result shows that Pb₆O₄?BO₃??NO₃?has relative large birefringence.