Luminescence of Copper-Activated Orthophosphates of the Type ABPO[sub 4] (A = Ca, Sr, or Ba and B = Li, Na, or K)

Activation of orthophosphates of the type with copper gives an efficient phosphor in some cases. The brightest phosphors found are and , with an emission peak (with 2537Aå excitation) at 4150 and 4600Aå, respectively. The properties of orthophosphates of the type with two kinds of alkali earth or alkali metal ions, respectively, were also studied. X‐ray diagrams of the compounds investigated are given.