Preparation Of Alkaline Earth Metal Borate-based Luminescent Materials And Research On Their Luminescent Properties

The borate host luminescent materials have become one of the research focus.At present,it has got certain progress in the preparation and luminescent properties.However,the research system of borate host luminescent materials are still narrow and almost are focus on anhydrous borate host,and there are very few research on hydrated borate host.In addition,the preparation methods are few and mainly are prepared by high temperature solid-state method,the research about the relationship between the preparation method,condition and the morphology,luminescence properties of products are still need to be further studied.Therefore,broadening the research system of borate host luminescent materials,and further study the relationship between the preparation methods,conditions and the morphology,particle size,luminescent properties of products,will help to the find the new borate host luminescent materials,provide scientific basis for the research and application of borate host luminescent materials,it is also helpful to the exploitation and utilization of borate and boron minerals.In this work,we takes them as the research object,several hydrated and anhydrous magnesium borate,calcium borate,strontium borate and barium borate host luminescents were prepared,they were characterized by chemical analysis,EDS,XRD,IR,SEM,TG-DTA and their luminescent properties were also studied.The specific research content are as follows.Thorn spherical-like 2MgO·B2O3·2H2O assembled by nanowires and irregular spherical—like 2MgO·B2O3·2H2O:Eu3+ assembled by nanowires were prepared by hydrothermal method for the first time.Aggregated Mg2B2O5:Eu3+ was prepared by calcinning 2MgO·B2O3·2H2O:Eu3+.The result shows that the incorporation of Eu3+ has little effect on the structure,crystallinity and morphology of 2MgO·B2O3·2H2O.In addition,the effect of reaction time and Eu3+ doping amount on the luminescent properties of 2MgO·B2O3·2H2O:Eu3+ were studied,and the optimal preparation conditions were obtained.And it is found that the strongest emission peaks of 2MgO·B2O3·2H2O:Eu3+ and Mg2B2O5:Eu3+ was located at ? = 614nm(red)and ??592nm(orange),respectively,and the color purity(red)of 2MgO·B2O3·2H2O:Eu3+ is higher than the color purity(orange)of Mg2B2O5:Eu3+.The results indicating that the 2MgO·B2O3·2H2O:Eu3+ is a good red luminescent nanomaterials with low preparation temperature,regular morphology and high color purity.Eight hydrated calcium borate and eight Eu3+doped hydrated calcium borate host luminescent materials were prepared by hydrothermal method and phase inversion method.The results showed that the Eu3+ doping have different influence on the morphology and particle size of products,but very few influence on the structure of products.The eight Eu3+doped hydrated calcium borate host luminescent materials with different structure and morphology are as following:thorn spherical-like CaB2O4 0.5H2O:Eu3+ assembled by microsheets,microsheet-like CaB6O10·4H2O:Eu3+,triangular sheets aggregated CaB6O10·5H2O:Eu3+,Ca2B2O5·H2O:Eu3+ microribbon,thorn spherical-like CaB3O5(OH):Eu3+ assembled by microrods,microsheet-like Ca2B10O17·5H2O:Eu3+,nanosheet-like Ca2B14O23·8H2O:Eu3+ and irregular spherical-like Ca4B10O19·7H2O:Eu3+ assembled by nanosheets.Moreover,their luminescent properties were studied and found that their strongest emission peaks were corresponding to 5Do-7F2 transition of Eu3+,means they all exhibit red light emission.We studied the influence of surfactants type,Eu3+ doping amount on the luminescence properties of these eight hydrated borate luminescent materials,and we also investigated the effects of raw materials or preparation methods as well as reaction time on the luminescence properties of Ca4B10O19·7H2O:Eu3+and Ca2B10O17·5H2O:Eu3+,and the optimal preparation method and conditions were obtained finally.Ribbion-like Ca3(BO3)2:Eu3+ was prepared by calcining the precursor(Ca2B2O5·H2O:Eu3+)for the first time,By comparing the luminescent properties of Ca3(BO3)2:Eu3+ with that of Ca2B2O5·H2O:Eu3+,it was found their strongest emission peak position were the same,which were ascribed to red emission.In addition,It was found their emission intensity and O/R ratio are almost the same under their optimal excitation wavelength,indicating the Ca2B2O5·H2O:Eu3+ is a good red luminescent material.CaB2O4:Eu3+ was prepared by calcining the precursor(4CaO.5B2O3·7H2O:Eu3+)for the first time,it was found the strongest emission peak was located at ??588nm(orange).The impacts of preparation conditions of precursors and calcination temperature on the luminescent properties of CaB2O4:Eu3+ were studied,the optimal preparation conditions and calcination temperature were obtained.By comparison with another CaB2O4:Eu3+ which prepared by traditional high temperature solid state reaction method,we found the CaB2O4:Eu3+which prepared by calcining 4CaO·5B2O3·7H2O:Eu3+ show better dispersion,lower calcination temperature and better luminous intensity.The SrB2O4·4H2O and SrB2O4·4H2O:Eu3+ were synthesized by precipitation method,the SrB2O4 and SrB2O4:Eu3+ were synthesized by calcining precursor method.All products were characterized and their luminescent properties as well as the influence of prepration conditions on their luminescent propteries were investigated.The results show that the SrB2O4·4H2O and SrB2O4 exhibit strong emission in the UV region,SrB2O4·4H2O:Eu3+ and SrB2O4:Eu3+ exhibit strongest emission peak at ?=613 nm.It can be found obviously that the crystal water has strong quenching effect on the luminescence of host and Eu3+ doped luminescent materials,however,by prolong the reaction time and increasing the doping amount,the luminescence properties of SrB2O4·4H20:Eu3+ can be improved largely.And then the red luminescent material SrB2O4·4H2O:Eu3+ with similar emission intensity as SrB2O4:Eu3+ but lower preparation temperature,higher red orange ratio can be obtained.The SrB6O10·5H2O and SrB6O10·5H2O:Eu3+ were synthesized by precipitation method,the SrB6O10 and SrB6O10:Eu3+ were synthesized by calcining precursor method,and their luminescent properties were investigated.The results show that the SrB6O10·5H2O and SrB6O10 exhibit strong self-activated emission in the UV region,SrB6O10·5H2O:Eu3+and SrB6O10:Eu3+ exhibit strongest emission peak at ?=615 nm.In addition,the impacts of surfactants or additives on the morphology and luminescent properties of SrB6O10·5H2O:Eu3+ were studied,several SrB6O10·5H2O:Eu3+ with different morphologies were obtained and found the surfactants or additives have great impact on the luminescent properties of SrB6O10 5H2O:Eu3+ The SrB6O10·5H2O:Eu3+prepared with CTAB as the surfactant exhibite strongest luminescent intensity and highest R/O value.It also found the SrB6O10·5H2O:Eu3+exhibit higher R/O values,higher quenching concentration of Eu and higher stability for Eu3+ than SrB6O10:Eu.The spherical-like and rod-like Ba-B-O:Eu3+ and the novel Ba3B6O9(OH)6:Eu3+with brick-like morphologies were prepared by hydrothermal method,the granular-like Ba-B-O:Eu3+ was prepared by supersonic co-precipitation method for the first time.The spherical-lik,rod-like and sheet-like BaB2O4:Eu3+ were successfully obtained by calcining the precursors(Ba-B-O:Eu3+,Ba3B6O9(OH)6:Eu3+).The photoluminescent properties of precursors and BaB2O4:Eu3+were studied in detail.It is found the structure,morphology,particle size and Eu3+ doping amount has great influence on the luminescent properties of precursor and BaB2O4:Eu3+.Among these precursors,the granular-like Ba-B-O:Eu3+ exhibit the strongest PL intensity and highest quenching cencentration,the brick-like Ba3B6O9(OH)6:Eu3+ exhibit highest O/R value.Among the BaB2O4:Eu3+,spherical-like BaB2O4:Eu3+ shows strongest PL intensity and Eu3+quenching concentration,while the granular-like BaB2O4:Eu3+ shows highest O/R value.In addition,it was found the BaB2O4:Eu3+ exhibit much stronger PL intensity than their precursor,and found the Ba-B-O:Eu3+ is better than Ba3B6O9(OH)6:Eu3+ for prepare BaB2O4:Eu3+ with good PL properties.The spherical-like BaO·3B2O3·4H2O,BaO·3B2O3·4H2O:Eu3+ and nanobelt-like BaO·3B2O3·5H2O,BaO·3B2O3·5H2O:Eu3+ were prepared by hydrothermal method,the vermicular-like BaO·3B2O3·5H2O and spherical-like BaO·3B2O3·5H2O:Eu3+ were prepared by supersonic precipitation method.All of samples were characterized and their photoluminescence(PL)properties as well as the impacts of Eu3+ doping amount on their PL properties were studied.The results showed the structure,morphology and particle size of samples have great impact on their PL properties,and found the nanobelt-like BaO-3B2O3·5H2O:Eu3+ exhibit very strong PL intensity and high O/R value,which means it is a good red luminescent material with good PL properties.