COATED RARE EARTH OXIDE COMPOSITIONS AND A PROCESS FOR PRODUCING SAME

1,269,329. Luminescent materials and uses thereof. G.T.E. SYLVANIA Inc. 30 Oct., 1970 [30 Oct., 1969], No. 51822/70. Heading C4S. [Also in Division C1] A process for preparing a composition e.g. for phosphor for colour T.V. crts and colour display systems, of a partially acid soluble rare earth oxid...

Ausführliche Beschreibung

Gespeichert in:

Bibliographische Detailangaben
Hauptverfasser:	JAMES W. HAYNES, KENNETH H. SHANER
Format:	Patent
Sprache:	eng
Schlagworte:	ADHESIVES BASIC ELECTRIC ELEMENTS CHEMISTRY COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM,CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THERARE-EARTH METALS DYES ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR ELECTRICITY INORGANIC CHEMISTRY MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FORELSEWHERE METALLURGY MISCELLANEOUS APPLICATIONS OF MATERIALS MISCELLANEOUS COMPOSITIONS NATURAL RESINS PAINTS POLISHES SEMICONDUCTOR DEVICES
Online-Zugang:	Volltext bestellen
Tags:	Tag hinzufügen Keine Tags, Fügen Sie den ersten Tag hinzu!

Beschreibung
Zusammenfassung:	1,269,329. Luminescent materials and uses thereof. G.T.E. SYLVANIA Inc. 30 Oct., 1970 [30 Oct., 1969], No. 51822/70. Heading C4S. [Also in Division C1] A process for preparing a composition e.g. for phosphor for colour T.V. crts and colour display systems, of a partially acid soluble rare earth oxide coated with the corresponding rare earth orthophosphate comprises forming an aqueous suspension of finely divided oxide and 0.002 to 10À5 wt. per cent of the ortho-phosphate, adjusting the pH to 4 to 5 and maintaining for at least 10 mins, separating the solid, washing and heating to from 100 to 1250 C. for at least ¢ hour. A composition comprises 95 to 99.99 wt. per cent of the oxide, and 0.01 to 5 wt. per cent of them orthophosphate which coats the oxide, the composition having a bulk density at least 1 gm./cc. e.g. 2 to 8, greater than the uncoated oxide. The rare earth oxides are preferably of Y, Gd, Lu, La, Eu and mixtures thereof and the rare earth activated rare earth oxide phosphors of Y, Gd, La, Lu and mixtures thereof, the rare earth activator preferably being selected from Eu, Sm, Pr and Tb, e.g. Eu activated gadolinium oxide, gadolinium-yttrium oxide and yttrium oxide of bulk density 9.5 to 12.2. The product has improved handling characteristics and the oxide may also be used in the preparation of refractory metals and alloys e.g. small amounts of yttrium oxide to reduce excessive grain growth in ferrous chromium aluminium alloys and gadolinium oxide to give higher tensile strength to Ti. The oxide compositions are preferably acid soluble from 0.01 to 5 wt. per cent at a pH of 4 to 5. Preferred ortho-phosphate sources are orthophosphoric acid, and mono-ammonium orthophosphate, or may be sodium, potassium, diammonium, trisodium, or tripotassium orthophosphate, and nitric, or hydrochloric acid may control the pH, sulphuric and oxalic acids generally being avoided. At least 5 cc. of washing water ensures cation removal of the phosphate source to 5 p.p.m.