GB1170765A - Glass Compositions - Google Patents

Abstract

1,170,765. Luminescent material. OWENSILLINOIS Inc. 8 Sept., 1966 [9 Sept., 1965], No. 40088/66. Heading C4S. [Also in Division C1] In situ surface crystallizable glass compositions having a coefficient of linear thermal expansion of from 45 to 100 + 10<SP>-7</SP> per ‹C. consist of the following oxides in weight percentage SiO 2 45-65, MgO 10-20, ZnO 0-30, Na 2 O 0-17, K 2 O 0-20, Li 2 O 0-3, CaO 0-10, TiO 2 0-5, ZrO 2 0-5, MnO 0-2, Cn 2 O 0-2, CuO 0-2 and Sh 2 O 3 0-2, wherein the amount of Na 2 O + K 2 O + Li 2 O is at least 10 weight per cent. Cathodoluminescent in situ surface crystallized glass bodies are prepared by heating the above compositions through the annealing point range of the glass composition to a higher temperature approaching but not substantially above its Littleton softening point (e.g. from 200‹ to 20‹ F. below its Littleton softening point) and holding the composition at this temperature until the desired degree of surface crystallization has been obtained. Luminescent glass articles containing a multicolour phosphor combination grown in the surface of the glass comprise the above cathodoluminescent in situ surface-crystallized glass body upon the surface of which has been deposited and subsequently heat-treated in situ at least one layer containing an activator for the crystalline phosphor contained in the surface layer of the glass composition, the heat treatment being effected into and at a temperature not substantially exceeding the Littleton softening point of the glass composition until there has been formed at least one layer of a crystalline activated phosphor, the phosphor combination causing the luminescent article to luminesce one colour at one voltage and a different colour at a different voltage. Thus a luminescent glass article containing a two-colour phosphor combination grown in the surface of the glass comprises the above cathodoluminescent, in situ surfacecrystallized glass body which contains from 1 to 5 weight per cent TiO 2 but no ZrO 2 , MnO, Cn 2 O, CnO or Sb 2 O 3 and upon the surface of which has been deposited and subsequently heat-treated in situ a layer comprising a manganese (M 2 <SP>++</SP>)-containing activator for the crystalline MgSiO 3 -type phosphor in the surface layer of the glass composition, the heat-treatment being effected up to and at a temperature approaching but below the Littleton softening point of the glass composition until there has been formed a layer of a crystalline manganeseactivated MgSiO 3 -type phosphor which when subjected to low-voltage electron bombardment luminesces the red colour of the crystalline manganese-activated MgSiO 3 -type phosphor and to luminesce the blue colour of the underlying crystalline Ti-modified MgSiO 3 -type phosphor when subjected to high-voltage electron bombardment. Instead of two-colour a higher number of colour-phosphor combinations may be built up in a similar manner. Oxides, sulphides and halides of metals may be included as colourants or to improve the working properties e.g. oxides of cobalt, nickel or chromium in amount up to 3% by wt. Activators other than TiO 2 , ZrO 2 , MnO, Cu 2 O and CuO may be employed. Applications instanced include lamp bulbs, light screens and c.r.t's.