X-ray fluorescent luminescent cadmium tungstate compositions

US4115312A · kind A · utility

Assignee

• Merck Patent GmbH · DE

Inventors

• Gerhard Engel · Stuttgart, DE
• Manfred Eckle · Darmstadt, DE

Key dates

• Filing date: May 5, 1977
• Grant date: Sep 19, 1978
• Expiry date: May 5, 1997

Classification

• Technology area (CPC G): Physics
• CPC primary: G21K4/00
• WIPO field: Engines, pumps, turbines
• WIPO sector: Mechanical engineering

Abstract

In a process for producing x-ray fluorescent luminescent cadmium tungstate material by precipitation of cadmium tungstate from an aqueous solution of an alkali metal tungstate by the addition of an aqueous solution of a cadmium salt and separation, washing, drying and calcining of the resulting precipitate, an improvement is provided wherein PA1 (a) each of the alkali metal tungstate and cadmium salt solutions is at least 1N, PA1 (b) mixing of the two solutions is done over 0.1 to 4 hours, PA1 (c) approximately equivalent amounts of both solutions are mixed, PA1 (d) mixing is done at a temperature of 0.degree. C - the boiling point of the mixture, PA1 (e) the precipitate is activated by calcination at a temperature between 400.degree. and 1200.degree. C for up to 6 hours, and PA1 (f) the thus-activated precipitate is reslurried in water, washed and dried.