| Ce3+-doped yttrium aluminum garnet(CexY3-3xAl5O12, Ce:YAG) is a kind of scintillator with high chemical stability, high melt point, high light yield and fast decay timeing et al, which make them the promising materials especially for middle-low energy ray detecting. However, The YAG crystal has several disadvantages, such as its fabrication process is very complicated and it is hard to fabricate in a large size and with Ce3+high concentrations, and all these disadvantages have limited its application. Meanwhile, as YAG has cubic crystal structure, the merit of its homogeneous optical properties and lack of birefringence effects determined that YAG transparent caremics could substitute for single crystal if proper synthesis methods of YAG powders and ceramics are adopted.In the present work, chemistry coprecipitation method was used to synthesize the Ce:YAG nanosized powders, which were used to make transparent ceramics by cold isostatic pressing and sintering in vacuum. The relations between the synthesis technology and the performance of the powders have been investigated systematically, while the effects of powder properties,the amount of additive and sinterring temperature on the sinter-ability and optical properties of the caramics have aslo been discussed.Firstly, Ce:YAG nanoparticles were prepared by chemistry coprecipitation method with NH4HCO3 as the precipitant. It was found that PH values, the kind of dispersant and the calcination temperature on the formation of YAG affected properties of the powder profoundly. The results show that the precursors prepared are mainly compound of carbonate, and we could obtain pure YAG phase powder after calcination them at 900℃without any transition phases appearing.When the PH values of the reaction solution is at 7.5, theζ-potential is the strongest, which will hinder the powders agglomeration. The results showed that the precursor that was washed by absolute ethyl alcohol after washed by deionized water, which can effectively remove the surface moisture and block the formation of bridge oxygen bond, has a good dispersion. During the process, different kinds of surfactants were used to improve the dispersity of the powders. In this experiment, (NH4)2SO4 played the best effect. With the increase in calcination temperature, the agglomeration and bonding between particles become serious, which will affect the sinter-ability. When the PH value of the precipitation solution was controled at 7.5, while the calcination temperature kept at 900℃for 2h, well dispered YAG powders with average particle size of about 60nm were obtained in the presence of (NH4)2SO4 as the surfactants.Secondly, the well dispersed nanosized powder was used to prepare high density Ce:YAG ceramic by double-sided dry-pressed and cold isostatic pressing, meanwhile the additive was added. Afrer vacuum sintered at 1750℃for 10h, the ceramic in size ofΦ20×2mm was fabricated with the light-transmittance of above 70% at 800nm. It is found that as the specific surface area of the powder increases, the relatived sensity of sintered ceramic increases at first,and then lows down. The decay times of YAG ceramics with Ce3+ concentration from 0.5mol% to 4mol% with 450nm wavelenth light excitation are almost the same, about 62ns.
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