ELECTRO- AND PLASMA CHEMICAL TECHNOLOGIES Effect of Plasmochemical Modifi cation on Electro-Optical and Surface Properties of Zinc Sulfi de Electroluminescent Phosphors

Abstract —Method for improving the brightness of photo- and electroluminescence from ZnS:Cu and ZnS:(Cu, Al) phosphors by their treatment in a low-temperature gas-discharge plasma was developed. The relationship between the luminescence brightness and spectra and surface properties of the phosphors was studied. The mechanism of processes that occur on the surface and in the bulk of phosphor particles during their bombardment with plasma ions was determined. DOI: 10.1134/S1070427212120099 Electroluminescent sources of light, based on powdered zinc sulfi de electroluminescent phosphors (ELPs) have been known rather long. However, despite the numerous advantages (low electric power expenditure, small weight, fl exibility, shock resistance), their application is restricted by the insuffi ciently high brightness. Various treatment methods can be used to raise the brightness of zinc sulfi de ELPs. For example, modifi cation with medium-energy electrons has been used previously [1–6] for this purpose, which made it possible to substantially raise the brightness of fi nished ELPs [7]. The main obstacle to industrial application of this method is that it requires rare and expensive equipment: medium-energy electron accelerator of the resonant-transformer type. It is desirable to use for industrial purposes a lower cost and more easily implementable method for modifi cation of ELPs. A possible candidate is the plasma treatment.In contrast to medium-energy electrons, which have a high penetrating capacity and act on the entire volume of phosphor particles, plasma ions affect only their surface layers. Therefore, purposeful control over the ELP properties via plasma modifi cation requires a study of how plasma ions affect the bulk and surface properties of ELP particles.As object of study were chosen the industrial ELPs E-455-115(220) (chemical composition ZnS : Cu) and E-515-115(220) [ZnS : (Cu, Al)] manufactured by NPF Lyuminofor ZAO (Stavropol).Our communication reports on a study of the effect of a plasma treatment of these phosphors on their electro-optical and surface properties.EXPERIMENTALThe plasmochemical modifi cation of the ELPs in a low-temperature gas-discharge plasma was carried out on an NNV-6.6I1 installation (Bulat).The vacuum chamber of the installation has the form of a vertical cylindrical vessel with a side opening closed with a door. The case has double walls forming a hollow for water cooling or heating. There is a spiral cathode inside the chamber, with the chamber walls serving as the anode. A phosphor to be treated is placed on a rotating metallic table situated at the chamber center.