Synthesis,structure And Properties Studies Of Two New Types Of Phosphate And Selenite Inorganic Functional Materials

Phosphate and selenite inorganic functional materials have attracted more and more attention due to their important applications in the fields of nonlinear optics,luminescence,electrochemistry,and magnetism.In this article,we designed and synthesized two new phosphates AZnAl?PO₄?₂?A=Na,K,Rb?and selenite MBi?SeO₃?₂?H₂O?Cl?M=Co,Ni,Cu?inorganic functional crystal materials,analyzed their crystal structures,studied their optical,electrical,and magnetic properties and potential applications.The results are summarized as follows:1.Phosphate AZnAl?PO₄?₂?A=Na,K,Rb?crystal system.NaZnAl?PO₄?₂ and KZnAl?PO₄?₂ were synthesized by high temperature solid phase method,and RbZnAl?PO₄?₂ was synthesized by hydrothermal method.NaZnAl?PO₄?₂ crystallizes in the triclinic center-symmetric space group P-1?No.2?,Z=2,its unit cell parameters are a=8.2050?9??,b=8.8142?9??,c=9.4997?10??;KZnA l?PO₄?₂and RbZnAl?PO₄?₂ are isomorphic compounds,both belong to monoclinic system centrosymmetric space group C2/c?No.15?,Z=8,and their unit cell parameters are KZnAl?PO₄?₂:a=13.2906?7??,b=13.1956?8??,c=8.6660?5??and RbZnAl?PO₄?₂:a=13.3534?12??,b=13.1741?12??,c=8.9333?8??,respectively.The main structural features of the crystals in this system are that they all have a three-dimensional tunnel frame structure formed by ZnO₄,AlO₄ and PO₄ tetrahedrons by sharing the oxygen atoms,and alkali metal ions distributed in the tunnel structures.Interestingly,by comparing the crystal structure of AZnAl?PO₄?₂?A=Na,K,Rb?,it can be found that the structural symmetries show a gradually rising tendency from Na to K?Rb?as a result of cation size effect of alkali metals.In addition to the single crystal structure,we have also characterized their physical properties:ultraviolet,infrared,thermal stability,and electrical conductivity.In order to expand the application range of phosphate,we conducted rare earth doping experiments on AZnAl?PO₄?₂?A=Na,K?to explore its possible applications in the field of fluorescent materials.2.Selenite MBi?SeO₃?₂?H₂O?Cl?M=Co,Ni,Cu?crystal system.The three cases of selenite isomorphic compounds were synthesized by hydrothermal method,and the crystal structure was determined by single crystal X-ray.They are crystallized in the orthorhombic Pbca space group,Z=8.Cell parameters CoBi?SeO₃?₂?H₂O?Cl:a=14.0563?0??,b=7.5815?2??,c=14.9961?5??;NiBi?SeO₃?₂?H₂O?Cl:a=14.0827?4??,b=7.5752?24??,c=14.8604?4??and CuBi?SeO₃?₂?H₂O?Cl:a=14.5757?5??,b=7.3706?2??,c=14.6563?5??.Their structural feature is a three-dimensional frame topology with two-dimensional cross tunnels,adjacent CoO₅Cl octahedrons are connected into Co₂O₈Cl₂ dimers by a co-edge method,and the dimers bridges the two-dimensional[Bi?SeO₃?₂]_?layers together to form the three-dimensional crystal structure of the compounds.The UV-Vis-NIR diffuse reflectance spectroscopy test shows that the three compounds are broad band gap semiconductors with band gaps of 3.7eV,3.5eV and 3.2eV,respectively;the variable temperature susceptibility test shows that the three compounds are all high-spin antiferromagnetic materials,and the phase transition temperatures are 6K,18K and52K,respectively.