| abstract |
A phosphor that emits light having a wavelength different from that of the radiated exciting light, the phosphor comprising ultrafine particles having an average size smaller than the wavelength of the fluorescence emitted therefrom at the maximum luminous intensity or the wavelength of the exciting light at the maximum luminous intensity; a process for producing the phosphor; a composition containing the phosphor; and ink ribbon, fluorescent mark carrier, optical character reader, article sorting system, detection mark and mark-detecting method, each utilizing the phosphor. An example thereof is one represented by the general formula: LnxA1-xPO4, wherein: Ln represents at least one element selected from the group consisting of Nd, Yb and Er; A represents at least one element selected from the group consisting of Y, La, Gd, Bi, Ce, Lu, In and Tb; and x is a number ranging from 0.01 to 0.99. |