Editing Phosphor (section)

====Black-and-white television CRTs====
The black-and-white television screens require an emission color close to white. Usually, a combination of phosphors is employed.

The most common combination is {{chem2|ZnS:Ag + (Zn,Cd)S:Cu,Al}} (blue + yellow). Other ones are {{chem2|ZnS:Ag + (Zn,Cd)S:Ag}} (blue + yellow), and {{chem2|ZnS:Ag + ZnS:Cu,Al + Y2O2S:Eu(3+)}} (blue + green + red – does not contain cadmium and has poor efficiency). The color tone can be adjusted by the ratios of the components.

As the compositions contain discrete grains of different phosphors, they produce image that may not be entirely smooth. A single, white-emitting phosphor, {{chem2|(Zn,Cd)S:Ag,Au,Al}} overcomes this obstacle. Due to its low efficiency, it is used only on very small screens.

The screens are typically covered with phosphor using sedimentation coating, where particles [[suspension (chemistry)|suspended]] in a solution are let to settle on the surface.<ref name="lumdisp">Lakshmanan, p. 54.</ref>