Doped lanthanide oxy-halide phosphor coating prodn. esp. on TV screen - by adding silicon alcoholate to aq. dispersion and stirring before sedimentation

摘要

Sedimentation of phosphor particles based on doped lanthanide oxyhalides (I), esp. LaOBr:Tb (IA), from an aq. suspension contg. coagulant to form a phosphor coating on a substrate (II) is carried out in stages, involving: (1) dispersing (I) in water vigorously, pref. with an Ultraturax (RTM) stirrer; (2) dispersing a Si cpd. (III) with an alcohol ligand, esp. tetramethyl orthosilicate Si(OMe)4 (IIIA) in the suspension, pref. dropwise; (3) stirring the mixt. for at least 6 min. and then placing it in a sedimentation bath on (II); and (4) after sedimentation, isolating the phosphor coating on (II), pref. by decantation or suction. USE/ADVANTAGE - The process is used in the prodn. of TV screens. It ensures good adhesion of the coating and a high ratio of luminescence to stimulation radiation energy, since the (I) particles are deposited as flaky, rather than spherical, particles, many with their max. area vertical to the surface of (II)ing i