The invention relates to a compound based on at least one element A chosen
from alkaline-earth metals, on at least one element B chosen from
aluminium, gallium and indium, on sulphur and on a dopant capable of
giving the compound luminescence properties, which is characterized in
that it is in the form of a mixture of predominantly an AB.sub.2 S.sub.4
-type crystallographic phase and a B.sub.2 S.sub.3 -type crystallographic
phase. This compound is prepared by a method in which a solution or
suspension comprising salts or sols of the elements A, B and of the dopant
is formed in a proportion such that the B/(A+dopant) atomic ratio is at
least 2.06; the solution or suspension is spray-dried; the product thus
obtained is sulphurized. This compound may be used as a phosphor,
especially in cathodoluminescence.
