摘要
Borates are advanced optical materials that demonstrate broad application prospects in the field of birefringence.This study employed a low-temperature flux method to synthesize two novel alkaline metal fluorozincoborates,namely,Na_(6)ZnF_(2)(B_(12)O_(24))and KZn_(3)F(BO_(3))^(2).They crystallize in the R3¯c and P63/m space groups,respectively.Na_(6)ZnF_(2)(B_(12)O_(24))H6 possesses isolated high-symmetry[ZnF_(2)(B_(12)O_(24))]^(12-)groups,based on corner sharing[BO4]5-tetrahedra,[BO_(3)]^(3-)triangles,and[ZnO3F]5-tetrahedra.Sixmembered rings(6-MRs)are contained in the[B12O24]12-groups,into which were inserted[ZnO3F]5-tetrahedra via sharing common vertices.In contrast,KZn_(3)F(BO_(3))^(2)features an unprecedented three-dimensional(3D)[Zn3(BO3)2F]-framework,which was constructed by[BO_(3)]^(3-)triangles,[ZnO6]10-octahedra,and[(ZnO3)2F]9-dimers.Two types of 6-MRs were contained in the structure along the a-and b-axes,built by two[BO_(3)]^(3-)triangles and four[ZnO3F]5-tetrahedra.Optically,Na_(6)ZnF_(2)(B_(12)O_(24))exhibits moderate birefringence(Δncal.=0.04@546 nm,Δnexp.=0.05@546 nm).Remarkably,KZn_(3)F(BO_(3))^(2)exhibits the highest birefringence(Δncal.=0.11@546 nm,Δnexp.=0.09@546 nm)within the zinc borate family,in which theπ-conjugated modules,[BO_(3)]^(3-),are the key source of the large optical anisotropy.The synthetic processes,elemental analyses,topological structures,thermal stability,Raman spectra,UV-Vis-NIR diffuse reflectance,and birefringence properties were systematically investigated.This work not only enriches the structural chemistry of fluorozincoborates,but also provides valuable insights for the rational design of novel birefringent materials.
基金
the Funding of Nanjing Weizhi Biotechnology Co.,Ltd(902/22050125011)and Anhui New Era Education Quality Project(2022qyw/sysfkc042)
Materialrelated Major Services for Anhui Province’s Emerging Industry Projects(2024fwxx032)
Inorganic Non-Metallic Materials Engineering Program Upgrade Project(2023zygzts043)
theNatural Science Foundation of Fujian Province(2023J05037)
the Open Foundation of State Key Laboratory of Structural Chemistry(20230007)
the National Natural Science Foundation for Youth(22301162)
the Startup Research Fund of Henan Academy of Sciences(No.241840189).
