A method for the production of oxysulfide - phosphors with a high portion of the same magnitude

摘要

1452898 Luminescent materials RCA CORPORATION 30 Oct 1973 [30 Oct 1972] 50489/73 Heading C4S A method for preparing activated Y, or Gd or Y-Gd oxysulphide phosphors comprises heating between 700‹ and 1250‹ C. a mixture including (a) at least one of yttrium oxide and gadolinium oxide, (b) at least one of sodium fluoride, potassium fluoride, ammonium fluoride, yttrium fluoride and gadolinium fluoride in amount 0À01 to 0À30 gram atoms of fluoride radical/grm. atom of Y and/or Gd, (c) at least one activator in gram atom ratio to the Y and/or Gd of 0À001 to 0À01 and (d) a sulphur containing composition selected from alkali thiocyanates, alkali rhodanides, and compositions which yield alkali sulphides and polysulphides on heating, then cooling to room temperature. "Alkali" is defined to mean Na, K, NH 4 , Cs and Li. The process produces larger particles (e.g. 3À9 to 8À4 Á) including sintered agglomerates. Activators may be one or more of Dy, Er, Eu, Ho, Nd, Pr, Sm, Tb and Tm. Detailed preparations are included. Additives such as phosphates, sulphates, arsenates and/or germanates of one or more alkalis which are washed out after heating increase brightness. (Y 0À965 Eu 0À035 ) 2 O 2 S is specified and Tables I and II include details such as C.I.E. co-ordinates. The phosphor may be incorporated in an electron beam device.