The Exploration,Syntheses And Characterization Of Thioindiumates And Thiostannates Infrared Photoelectric Functional Crystals

The development of photoelectric functional crystals affects every aspect of society.For example,the KBe₂BO₃F₂,β-Ba B₂O₄,KH₂PO₄,KTi OPO₄,Li Nb O₃crystals in UV-visible range and Ag Ga S₂,Ag Ga Se₂,Zn Ge P₂ in IR range,which are widely used in laser application,birefringence,nonlinear optics and so on.Chalcogenides are one of the most ideal candidate systems due to the wide IR transmission window and rich structure chemistry.In this paper,aiming at the design and synthesis of new IR photoelectric functional materials,based on the solid-state methods,nearly twelve new structures have been successfully designed and synthesized.Through the structure-property relationship,we discuss the optical performance difference causing by the dimensional transition between the covalent framework of thiostantates,especially for their birefringence,as well as the influence of the optical band gaps by introducing fluorine elements into the thioindiumates.These studies will provide a new insight for the design and synthesis new IR photoelectric functional materials and will facilitate the exploration of new IR photoelectric functional materials.1.Mixed-alkali metals thiostannates A₄Sn₃Q₈（Q=S,Se）By introducing the mixed alkali metals into the Sn containing system,we successfully synthesized two new similar chemical formula compounds,K₂Na₂Sn₃S₈and Rb₃Na Sn₃Se₈.They have a large difference between their birefringence,0.070and 0.196 respectively.The analyses for their structure-property relationship have shown that the edge-sharing connection modes between Sn Q_n（Q=S,Se）polyhedra will be favorable for the generation of the large birefringence.These studies will provide a new insight for the origin of birefringence and will facilitate the exploration of new IR birefringent crystals.2.Mixed anions thioindiumates Na₂Ba₁₇In₈Q₂₁F₁₈and KBa₂In Q₃F₂（Q=S,Se）The laser damage threshold of chalcogenide is closely related to its band gap.Increasing the electronegativity difference of the structure is beneficial for the band gap of the compounds.Fluorine is the biggest electronegative element.The introduction of fluorine into an In containing system mixed alkali metals and alkaline earth metals can increase the electronegativity difference of the structure.In this system,we successfully synthesized four new compounds.The performance measurements show that their optical band gaps increase significantly comparing with the compound without F,which would be helpful to study the influence of the optical properties in mixed anions compounds.3.Synthesis of other compoundsIn the first two parts of the study,we also have obtained some other new structures,for example,Li₂Rb₂Ga₃S₆Cl,crystallizing in orthogonal space group Pna2₁,Li Cs Ga₂S₄,crystallizing in monoclinal space group P2/c,etc.The discovery of these structures enriches the diversity of chalcogenide and has potential application prospects in nonlinear optics,energy storage and other fields.