Method for chemically modifying composition on outer surface of phosphor particles, method for improving lamp light flux maintenance, phosphor powder, and phosphor coating composition

摘要

The composition of the outer surfaces of particles of a phosphor is chemically modified by substituting selected cations for cations of the phosphor at the surfaces by an ion exchange reaction. Also claimed are: (1) a process for improving lumen maintenance of a lamp; (2) a phosphor powder comprising individual particles of phosphor material where the outer surfaces of each particle have cations replaced with other selected cations; and (3) a phosphor-coating composition for coating an inner surface of a lamp envelope comprising a suspension of a phosphor powder in a solution of a binder and an aqueous medium.