Study On The Thermochemistry Of Mixed Metal Anhydrous Borate And Its Rare Earth Doped Luminescence Properties

Mixed metal borate systems are considered to be excellent non-linear optical materials,fluorescent materials and birefringent materials.In recent years,there have been many studies on the synthesis,characterization and nonlinear optical properties of mixed metal borates,but the research on the thermochemical properties of mixed metal borates and the research reports on their rare earth doped luminescent materials are few,and it is necessary to further study them.Thermodynamics is the fundamental data of physical chemistry and it has an important role in scientific research and industrial production.The thermochemical data can provide the stability and reactivity of the materials used.In this paper,as the continuous study the thermochemistry of mixed metal borate,we have synthesized four kinds of mixed metals borates with nonlinear optical properties of NaCaBO3,Li4CaB2O6,Li6Zn3B4O12 and Na3ZnBsO10 by high-temperature solid state reaction method,which were characterized by XRD,EDS,IR,TG and chemical analysis.Their basic thermodynamic parameters were determined by microcalorimetry.In addition,the preparation and luminescence properties of rare earth doped phosphors of Li6Zn3B4O12 and Na3ZnB5O10 were also studied.According to the design of the thermodynamic cycle,the enthalpies of solution of the NaCaBO3/Li4CaB2O6/Na3ZnB5O10/ZnO in 1 mol·L-1 HCl(aq),of Li6Zn3B4O12 in(H3BO3+ HC1)(aq),of CaCl2·2H2O(s)in two different solvents of(H3BO3+ HCl+NaCl)(aq)and(H3B03+HCl+LiCl·H2·)(aq),LiBO2(s)/NaB02·4H20(s)in(H3B03+HCl+ZnO)(aq)were measured,respectively.With the incorporation of the previously determined enthalpies of solution of ZnO(s)in(H3BO3+ HCl)(aq),of NaCl(s)in(H3BO3+ HCl)(aq),of LiCl·H20(s)in(H3BO3+ HCl)(aq),and of H3BO3(s)in 1 mol·dm-3 HCl(aq),together with the use of the stand of enthalpy of formation for CaCl2·2H20(s),LiCl·H2O,NaCl(s),LiBO2(s),NaB02·4H20(s),ZnO(s),H3B03(s),HCl(aq)and H20(1),the stand of enthalpy of formation of-(1664.5±0.9)kJ·mol-1 for NaCaB03,-(3391.7± 1.9)kJ·mol-1 for Li4CaB206,-(5867.5±4.8)kJ·mol-1 for Li6Zn3B4O12 and-(4655.3±6.6)kJ·mol-1 for Na3ZnB5O10 at 298.15 K were obtained on the basis of the appropriate thermochemical cycles.The rare earth Eu3+ and Tb3+ single doped Li6Zn3B4O12 and Na3ZnB5O10 luminescent materials were synthesized by high temperature solid phase method,and the effects of different kinds of rare earth ions with different concentrations on the luminescence properties of the matrix were investigated.It was found that the increasing doping concentration of Eu3+ makes the Li6Zn3B4O12:Eu3+ slightly redshift,and the higher the concentration,the stronger the fluorescence;The fluorescence intensity of Li6Zn3B4O12:Tb3+ phosphor was enhanced with the increase of Tb3+ doping concentration,in which the quenching concentration of Tb3+ was 0.5%.The results obtained in this paper can further enrich the research contents of mixed metal borate materials,and provide the basic data and experimental basis for the application of the mixed metal borate materials.