耐湿性荧光粉和X线增感屏

稀土发光材料溴氧化镧掺铽是一种高效率X线发光材料.但其化学性质很不稳定,特别是在潮湿的空气中,易潮解而使发光效率显著降低,甚至完全丧失发光能力.因此,如何防止溴氧化镧的潮解成了这一优良新材料能否应用的关键问题.本文提出了一种制备耐湿性溴氧化镧荧光粉的新方法.用这种方法制成的LaOBr:Tb荧光粉在75℃水中浸泡105小时发光强度基本不变,这种荧光粉及其所制成的X线增感屏,在45℃饱和水蒸汽压恒温室内放置265天,发光强度和屏对x光胶片的感黑度也基本保持不变.而原来的LaOBr:Th荧光粉在70℃水中浸泡不到20分钟就发生水解变质,原来的LaOBr:Tb荧光粉及增感屏,在45℃饱和水蒸汽压恒温室中放置不到10天就发生了水解变质.

MOISTURE-RESISTANT PHOSPHOR AND X-RAY INTENSIFYING SCREEN

Terbium-activated lanthanum oxybromide phosphor is a highly efficient X-ray luminescent material, but its chemical property is very unstable,particularly in a moisture containing atmosphere.In this paper, a new method of preparing moisture-resistant terdium-activated lanthanum oxybromide Phosphor and X-ray intensifying screen is provided:Firstly, a small quantity of water-unsolvable substance, such as aluminium Phosphate, aluminium sili-cate,aluminium hydroxide, zinc Phosphate or zinc silicate etc, is deposited on the surface of phosphor particles.Secondly,the Phosphor particles with appropriate quantity of anhydrous magnesium sulfate are mixed by ball mill, so that the Phosphor particles surrounded by anhydrous magnesium sulfate powder. The method of Xrray intensifying screen is the same as that of calcium tungstate screen.The Phorsphor, after immersion in water at 75℃ for 105 hours, showed no decrease in the emission in tensity, whereas the Phosphor started to hydrolyze after 20 minutes.The phosphor and the X-ray intensifying screen after storage at 45℃ and 100% hymi-dity for 260 days, also showed no decrease in the emission intentity,but the untreated phosphor and screen started to show a marked decreese in the emission intensity after about 10 days.