| 摘要 |
Novel infrared sensitive (stimulable) luminescent compositions of matter and method of preparing same. The luminescent composition of this invention comprises (1) a base (host) matrix selected from the group consisting of strontium sulfide, calcium sulfide, strontium selenide, calcium selenide and mixture of the foregoing; (2) activators (e.g. europium and samarium) present in said base matrix to provide doubly activated infrared phosphors; and (3) fluxing agents (e.g., CaF2, SrF2, LiF MgF2, SrSO4, SrSO3, NaCl, SrCl2, SrO, etc.), said base matrix being in a recrystallized form as a result of firing the doubly activated and fluxed base matrix under suitable recrystallization conditions whereby a part of the anions of the base i.e., sulfur, selenium and both sulfur and selenium, have been replaced by anion complexes S Se of sulfur and selenium atoms, said anion complexes forming with the base matrix a homogenous solid solution so as to provide a noval phosphor having improved luminescent characteristics in the form of luminescent crystals. The aforementioned sulfur selenium anion complexes may be represented by the formula Sn Sem wherein n is 1 to x and m is 1 to y wherein x and y are the number of maximum atom rings possible at the temperature at which the anion complexes formed. More particularly, in preparing the improved infrared sensitive phosphors of this invention, the abovementioned doubly activated and fluxed base matrix is subjected to a recrystallization heating step in a suitable furnace with an inert atmosphere which causes the base matrix because of thermal decomposition to release anion particles i.e., sulfur or selenium or sulfur and selenium depending upon the make up of the base matrix. The release of such anion particles results in the matrix containing small vacancies, holes or pits when the sulfur, selenium or sulfur and selenium material is released from the matrix. These small holes, vacancies or pits are filled during the recrystallization step by the absorption from the surrounding atmosphere of vapor particles which are anion complexes of sulfur and selenium atoms, said anion complex particles serving to improve the luminescent characteristics of the resulting infrared sensitive phosphors. The aforementioned anion complex vapor particles are formed from appropriate sulfur, selenium or sulfur and selenium ions provided in the atmosphere from thermal decomposition of the matrix base and in some instances from independent sources, or from components that might be present in the base matrix. |
