Electrodeposition of luminescent composite metal coatings containing rare-earth phosphor particles

Abstract

Mixtures of acetamide and dimethylsulfone (DMSO₂) with dissolved anhydrous transition metal chlorides are introduced as new non-aqueous electrolytes for the preparation of composite metal coatings with embedded hydrophilic particles via an electrolytic co-deposition process. Red-emitting (Eu₂O₃ and Y₂O₃:Eu³⁺), yellow-emitting (Y₃Al₅O₁₂:Ce³⁺), green-emitting (Gd₂O₂S:Tb³⁺) and blue-emitting (BaMg₂Al₁₆O₂₇:Eu²⁺) rare-earth phosphor particles and yttrium oxide particles have been embedded into thin nickel and cobalt layers. The metal coatings with the rare-earth phosphor particles have a metallic lustre, but show at the same time photoluminescence upon irradiation with UV light. The spectroscopic and photophysical properties of the rare-earth phosphors are not modified by embedding them in the metallic host matrix. Different electrodeposition parameters were optimised in order to obtain well-adherent coatings with a uniform particle distribution. By preparing mixtures of the Y₂O₃:Eu³⁺ and Gd₂O₂S:Tb³⁺ phosphors, the emission colour could be varied from red to orange and yellow to green, depending on the mixing ratios. Embedding mixtures of yellow and blue phosphors in the metal layer made it possible to produce coatings with white photoemission.