Process for reclaiming rare earth oxysulfide phosphors

US3941714A · kind A · utility

Assignee

• GTE Sylvania Limited · US

Inventors

• James E. Mathers · Ulster, US
• Ramon L. Yale · Ulster, US
• H. David Layman · Ulster, US

Key dates

• Filing date: Dec 23, 1974
• Grant date: Mar 2, 1976
• Expiry date: Dec 23, 1994

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02W30/50
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

A process suitable for reclaiming europium-activated yttrium oxysulfide contaminated with europium-activated yttrium oxide and other non-rare earth cathodoluminescent phosphors comprises forming a relatively uniform admixture of specific fluxing agents, the contaminated yttrium oxysulfide phosphor, a sufficient amount of reactive rare earth source selected from reactive yttrium and europium sources to achieve a predetermined yttrium to europium ratio in the admixture and an excess of the theoretical amount of sulfur required to convert the yttrium oxide and the yttrium source to yttrium oxysulfide, heating the admixture at a temperature of at least 850.degree.C in non-oxidizing atmosphere for a time sufficient to convert the yttrium oxide and the yttrium source to a europium-activated yttrium oxysulfide whereby the rare earth materials form a cathodoluminescent material and whereby the non-rare earth materials form water soluble reaction products, washing the resulting material with sufficient water to remove water soluble materials leaving a cathodoluminescent europium-activated yttrium oxysulfide phosphor.