Synthesis And Characterization Of New Copper Phosphate Halides

Copper oxides have attracted great interests for their many fascinating physical and chemical properties,such as high temperature superconductivity,but there are still many problems in the study of their magnetic ground state.In 1983,Haldane first conjectured that integer-spin antiferromagnetic Heisenberg spin chains in the absence of interchain interactions have a finite gap,and only the half-odd-integer chains are gapless,and won the Nobel prize in Physics in 2016.However,the above conjecture is based on the ideal case such as no chain interaction,and the ground state of the one dimensional copper oxides is far more complicated than that.In addition,researchers are also extremely concerned about whether there is any energy gap in two-dimensional copper oxide with Triangle or Kagome lattices.As an important branch of copper oxides,copper phosphates are crucially important for researching on the magnetism of copper oxide due to their extremely rich structural chemistry.Because the structure framework of copper phosphate can be further enriched by the introduction of halogen ions,a large number of new structural models can be provided for exploring the magnetism of copper oxide with this method.In addition,the introduction of halogen ions can also help us obtain high-quality copper phosphate crystals.Therefore,in this paper,by using the phosphothermal method we have synthesized several new copper phosphate halides in the condition of "fluoride-rich,chloride-rich and water-poor".The main results are as follows:(1).A new one-dimensional copper phosphate chloride(Cs2Cu(H2O)Cl[PO(OH)(OH0.25)2]2)was successfully synthesized from a solvothermally-treated gel-like precursor by evaporation at room temperature.This method not only overcomes the shortcoming that the solvent can not be evaporated and the reaction can not be observed directly during the reaction process of the solvothermal method,but also makes up for the deficiency that the reaction conditions of solvent evaporation are too mild.In the crystal structure of the compound,Square-pyramids[Cu(ClO3)Cl]sharing equatorial and axial common chlorine ions form an unprecedented chloro-bridged copper(II)Cu-Cl-Cu zigzag chain.Magnetic analysis results show that due to the triangular distribution of copper ions in the chain,the compound is a geometrically frustrated antiferromagnet with the spin frustration parameter f>42.1,and can be used as candidate materials for researching spin liquids.(In general,the spin frustration parameter of the material is less than 5)(2).By using the phosphothermal method,several new copper phosphate halides with low dimensional magnetic structure and pore structure was successfully synthesized in the condition of "fluoride-rich,chloride-rich and water-poor".Among them,Na2Cu2P2O7F2 and Cs4[Cs0.14(H3O)0.86]NaCu9[P2O6(OH)]6Cl6 are novel copper phosphate halides with two-dimensional layered structure,A9Cu6(P2O7)4OCl3'xH2O(A?K,NH4,K0.91Cs0.09)and Na2Cs7Cu6(P2O7)4OCl3·xH2O are novel porous copper phosphate halides with 16-membered ring.The results of magnetic analysis showed that Cs4[Cs0.14(H3O)0.86]NaCu9[P2O6(OH)]6Cl6 could also be used as candidate material for the research of spin liquid due to the part of copper ions form the kagome structure and the spin frustration parameter(/)is more than 42.1.(3).By using the phosphothermal method,two new alkaline copper phosphate chlorides(Li6Cu5H(PO4)4O2Cl,Na4Cu12H8(PO4)8OCl10)and a rare alkaline copper phosphate halide containing fluorine and chlorine(Na2Cu5.8H0.4(PO4)4FCl·3.2H2O)were synthesized in the condition of "fluoride-rich,chloride-rich and water-poor".