Properties of Glass Implanted with Phosphorus for Radiotherapy

以5*10^<16>cm^<-2>注入磷离子的高纯硅玻璃，在30keV的温度下，在7天的时间内，磷几乎全部溶解在95‰的纯净水中。将该玻璃在H_2气氛中加热到400ºC，再在O_2气氛中加热到900ºC，玻璃中的磷变得不溶于水。这说明在400℃的温度下，磷的胶体生长，在900℃的温度下，磷的胶体被包裹在一层薄薄的SiO_2-P_2O_5玻璃层中。将硅玻璃注入氮离子和磷离子，再进行同样的热处理，得到高含磷硅玻璃，化学耐久性高，因为在热处理过程中磷的蒸发被氮化硅的形成所抑制。当磷离子以5*10^<16>cm^<-2>注入到50keV的硅玻璃中时，其浓度在50nm深度左右达到最大值，且未分布到玻璃表面。结果，尽管离子注入造成了表面结构破坏，但这种玻璃并没有将磷溶解到水中。此外，在200keV下注入磷离子的硅玻璃，即使注入1*10^<18>cm^<-2>的大剂量磷，也不溶解磷。期望通过本方法获得的玻璃可用于深部肿瘤的治疗。

Highly pure silica glass implanted with phosphorus ion at 30keV by 5*10^<16>cm^<-2> dissolved almost all the phosphorus into the pure water at 95ﾟC during 7days. When this glass was heated at 400ﾟC in H_2 atmosphere and then heated at 900ﾟC in O_2 atmosphere, phosphorus in the glass became insoluble into the water. This suggests that phosphorus colloid grew by the heat treatment at 400ﾟC and that colloids were encapsulated in a thin SiO_2-P_2O_5 glass layr by the heat treatment at 900ﾟC.When the silica glass was implanted with nitrogen ion as well as phosphorus ion, and then subjected to the same heat treatment, highly phosphorus-containing silica glass with high chemical durability was obtained, since the evaporation of phosphorus on the heat treatment was suppressed by formation of silicon oxynitride. When the phosphorus ion was implanted to the silica glass at 50keV by 5*10^<16>cm^<-2>, it showed the maximum concentration at about 50nm depth and did not distribute up to the glass surface. As a result, this glass did not dissolve the phosphorus into the water in spite of the surface structural damage caused by the ion implantation. Moreover, the silica glass implanted with phosphorus ion at 200keV did not dissolve phosphorus even if a large dose of phosphorus, 1*10^<18>cm^<-2>, was implanted. It is expected that the glass obtained by the present method is useful for deep cancer treatments.