Synthesis,structure And Optical Properties Of Mixed Alkali Metal/Alkaline Earth Metal Borates

Photoelectric functional crystal materials have become a hotspot in the field of materials science and engineering because of their wide application in spectrometers,microelectronics,information communication.The main purpose of this thesis is to design and synthesis the ultraviolet or deep ultraviolet optical crystal materials and a series of compounds have been synthesized using the high-temperature solution method and hydrothermal method.The main design strategies are as follows:?1?according to the theory of the number of cations proposed by P.Becker,two compounds with isolated BO₃ groups are designed and synthesized;?2?by combining the BO₃ and CO₃ anion groups,the alkali metal/alkaline earth metal cation borate-carbonates have obtained;?3?on the choice of cationic groups,introducing the Zn²⁺and Cd²⁺cations containing d¹⁰ electrons,due to the cation of this electronic configuration,it is beneficial to enhance the nonlinear optical coefficient.Therefore,two iodide nonlinear optical materials containing Zn and Cd tetrahedra were synthesized.The main research contents are as follows:1.Two lead cadmium borate with isolated BO₃:Pb_6.33Sr_1.67Cd?BO₃?₆ and Pb1.22Sr2.78Cd8?BO3?8According to the number of cations proposed by P.Becker,two borate with the isolated BO₃ groups were successfully synthesized by high temperature solution in PbO-SrCO₃-CdO-B₂O₃ system,but their structures are quite different.In the structure of Pb_6.33Sr_1.67Cd?BO₃?₆,The Pb₆O₆ rings connect Sr/PbO₉ polyhedra through edge-sharing to form the 2D?[Pb₆Sr/Pb₂O₁₂]^8-layers.In the structure of Pb_1.22Sr_2.78Cd₈?BO₃?₈,The Sr/PbO₈ polyhedra connect with each other to form the 1D?[Sr/Pb₂O₁₄]^24-chains.The calculated results suggest that Pb_6.33Sr_1.67Cd?BO₃?₆ and Pb_1.22Sr_2.78Cd₈?BO₃?have large birefringence of 0.101 and 0.093 at 1064 nm in borates system,respectively.2.Synthesis and characterization of four complex anionic group compounds:Ba₄M?CO₃?₂?BO₃?₂?M=Ba,Sr?and K₉[B₄O₅?OH?₄]₃?CO₃?X·7H₂O?X=Cl,Br?The planar configuration of the CO₃ and the BO₃ group have similar structural configuration,which can produce the large birefringence and second-order susceptibility.Ba₄M?CO₃?₂?BO₃?₂?M=Ba,Sr?:Two borate-carbonates with isolated BO₃ and CO₃ groups were successfully obtained in the open system by the high temperaturesolutionmethod.Twomixedhalogenborate-carbonates K₉[B₄O₅?OH?₄]₃?CO₃?X·7H₂O?X=Cl,Br?were successfully synthesized by the hydrothermal method.Ba₅?CO₃?₂?BO₃?₂ has a wide transmission window with short UV cutoff edge?<190 nm?,the TG-DSC curve showed that Ba₅?CO₃?₂?BO₃?₂ has good thermal stability.K₉[B₄O₅?OH?₄]₃?CO₃?X·7H₂O?X=Cl,Br?crystallize in the non-centrosymmetric?NCS?hexagonal space group P6?2c,which show the largest band gaps among the borate-carbonates systems.Their anionic group consists of isolated B₄O₉ polyhedrons and CO₃ triangles,which are rare in complex borate-carbonates.3.Two iodide nonlinear optical materials containing Zn and Cd tetrahedraTwo iodides containing Zn and Cd tetrahedra were successfully synthesized by the hydrothermal method,KCdI₃.H₂O and KZnI₃.2H₂O.KCdI₃.H₂O have large non-vanishing SHG coefficients,calculated as d₁₅=5.49 pm/V,d₂₄=-5.38 pm/V,and d₃₃=-0.26 pm/V.KZnI₃.2H₂O has only non-vanishing SHG coefficients of d₁₄=0.35pm/V.The calculated results suggest that KZnI₃.2H₂O has a large birefringence of0.11 at 1064 nm,which demonstrates that it is a kind of potential birefringence material.