Copper-Activated Calcium Orthophosphate and Related Phosphors

The preparation and properties of copper‐activated calcium orthophosphate and related phosphors are described. Copper‐activated β‐calcium orthophosphate phosphor fired in a reducing atmosphere produces a strong blue fluorescence peaked at 4800Aå under excitation by 2537Aå and cathode rays. With partial substitution of Ca by bivalent metals such as Be, Cd, and Sr the emission remains unchanged, while introduction of Mg and Zn gives a strong violet fluorescence peaked at about 4400Aå and 4500Aå, respectively. Phosphors containing boron produce a blue to greenish yellow fluorescence depending on the content of boron. All of these phosphors give a strong thermoluminescence. Only the blue fluorescent phosphor gives also a weak red emission stimulated by 3650Aå radiation. Introduction of Mn or Sn as secondary activators into Cu‐ activated β‐calcium orthophosphate or into the Cu‐activated substituted phosphors gives rise to a red band due to Mn or Sn in addition to the original blue or violet band. The luminescent properties of zinc or cadmium orthophosphate are similar in some respects to those of zinc or cadmium sulfide phosphors.