Bismuth activated rare earth oxybromide phosphors and X-ray image converters utilizing said phosphors
AssigneeGeneral Electric Company
InventorJacob G. Rabatin
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Abstract
Oxybromides of lanthanum and gadolinium activated with bismuth are found to be superior in their conversion efficiency of X-rays to visible light when compared with conventional X-ray phosphors. The incorporation of the ytterbium ion in these phosphor materials produces reduced afterglow when used in X-ray image converter devices such as X-ray image intensifier tubes, fluoroscopic screens, and radiographic screens.
Claims7
An X-ray image converter comprising well-formed crystals of a phosphor material having the general formula of LnOBr:Bi.sup.3+ wherein Ln is one or more of La and Gd, with Bi being present as an activator at a concentration level in the approximate range 0.0005 - 0.15 mole per mole of phosphor.
A rare earth oxyhalide phosphor of reduced afterglow having the general formula:
- Ln.sub.1-x-y OBr:Bi.sub.x Yb.sub.y
- wherein
- Ln is one or more of La and Gd
- x is from 0.0005 to 0.15 mole per mole of LaOBr, and
- Y from a small but effective amount to reduce afterglow up to approximately 0.01 mole per mole of LaOBr.
Dependencies are inferred from the claim text.