Abstract
A new orange‐emitting phosphor, (Ca, Mg)S:Mn, was developed to replace a Cd compound, 
, which is potentially an environmental problem. With 1.5% Mg and 0.8% Mn, the emission color of (Ca, Mg)S:Mn is equal to the brightness of a 9 or 12 in. monochromatic tube and is 20% higher than that of 
. The addition of Mg as well as the increased Mn concentration shifts the emission spectrum to longer wavelengths. The color being equal, the Mg doping cuts down the Mn concentration and the loss of efficiency caused by the concentration quenching. Another advantage is the larger stability under operation compared with 
. The emission under pulsed excitation has an exponential decay with a time constant of 5 ms at 10% of the emission peak. A serious disadvantage of alkaline earth sulfide phosphors has been difficulty in screening due to hydrolysis. In this work, this difficulty was reduced by modification of the production processes.