Synthesis,Structures And Properties Of New Metal Borates

Borate compounds have rich structure types,and have many important applicationins in mineralogy,nonlinear optics,laser material and other aspects,so it has been the hot topic of many scholars in recent years.Six main group metal borates(four alkali metal borates and two lead borates)have been synthesized under hydro(solvo)-thermal conditions.The structures of these new crystals were determined by the single crystal X-ray structural analysis,the crystals were also characterized by X-ray powder diffraction,thermosgravimetric analyzer,UV-Vis spectroscopy,infrared spectroscopy.The first chapter is the literature review,and introduces the research progress of the alkali metal borates and lead borates,especially introduces the deep ultraviolet second order nonlinear optical(DUV NLO)materials,the key components of solid-state lasers producing coherent light through a cascaded frequency conversion,have received extensive commercial and academic interest owing to their versatile scientific and technological applications.The second chapter introduces the synthetic experimental materials and experimental apparatus.The third chapter describes four new alkali metal borates which use alkali metal Li+、RB+ and Cs+ as counter ions and were synthesized under solvothermal conditions:Li2CsB7O10(OH)4(1)、LiCsB5O9(OH)·H2O(2)、LiRbB5O9(OH)·H2O(3)and Rb2B6O9(OH)2(4).Compounds 1-3 are composite alkali metal borates.Compound 1 is a two-dimension B-O layer structure with 14-MR channels,Li+ and Cs+ are located at the above channels.Interestingly,it has a cutoff edge below 190 nm,the overall SHG efficiency of compounds 1 is 2.5 KDP.The SHG measurements on the sieved Li2CsB7O10(OH)4 sample indicate that it is phase matchable,so the crystal has potential use in DUV NLO applications.Compounds 2 and 3 are homogeneous crystals,The[B10O18(OH)2]clusters being secondary building units(SBUs)link to each other via 0 atoms to form 2D B-0 layers,with Li+,Cs+ and H2O filling the graps,it has a cutoff edge below 190 nm,indicating that the crystal may have potential use in DUV applications.Compound 4 have 1D B-O chains with 8-MR channels,Rb+ are located in the space.In the four compounds,Li+ cations,Rb+ and Cs+ cations are located at the above channels,they have played an important role in balancing skeleton charge.The fourth chapter describes two new lead borates:CsPb4B10O17(OH)5·H2O(5)and RbPb4B10O17(OH)5·H2O(6).Compounds 5 and 6 are isostructural with different alkali metal.The space group of CsPb4B10O17(OH)5·H2O is Pbca,crystal cell parameters is a = 12.1554(6)A,6 b 12.8324(6)A,c = 25.7006(13)A,V= 4008.9(3)A3,Z = 4.Compound 5 has 3D frameworks structure,the structure of CsPb4B10O17(OH)5·H2O consists of[B10O20(OH)4]{B10} clusters and[Pb4O3(OH)]{Pb4} clusters,with Cs+ and free water molecules filling the graps.These results enrich the family of borate compounds,and are of great significance to the exploitation of DUV NLO borates materials.