BE529327A - - Google Patents

Description

       

   <Desc / Clms Page number 1>
 



   The present invention relates to a method of manufacturing luminescent materials and also to the materials produced by this method as well as to combinations of such materials with electrical devices suitable for bringing them to luminescence, for example. in electric discharge lamps and cathode ray tubes.



   A special object of the invention is to provide a process for producing luminescent materials of novel composition which are brought to luminescence by ultraviolet radiations with a wavelength of 30650 A and take on a color allowing their use in lamps. electric discharge in high pressure mercury vapor. in order to modify or correct the color of the light given by the mercury vapor discharge.
The materials made according to the invention may, however, have other applications. For example most of these materials, if not all. are excited by ultra-violet radiation of other wavelengths. for example 2537 A.

   and can be used, inter alia, in luminescent lamps with low mercury vapor pressure for lighting or watch. Many of these materials produced according to the invention are still excited, for example ,,, by cathode rays and can be used in the screens of cathode ray tubes.



   According to the invention. a method of manufacturing luminescent material is characterized by heating. in a reducing atmosphere, a mixture of barium oxide and / or strontium oxide, lithium oxide and silica or compounds yielding these oxides on decomposition during heating. the relative proportions of these oxides and / or compounds used being such that the molar proportion (BaO + SrO): Li2O is in the range 5 if to 1: 5 and that the molar proportion of (BaO + SrO + Li2O):

   SiO2 is in the range 3 if at 1: 1. by adding a cerium compound. so as to produce a lithium silicate (barium. strontium), activated with cerium which can be excited to luminescence by ultra-violet radiators of 3560A
The starting mixture may also contain a manganese compound as an additional activator of the luminescent material obtained.
The luminescent materials produced by the process of the invention are referred to herein as lithium silicates (barium, strontium), but of course this expression does not imply the relative stoichiometric proportions of the oxides used.

   In view of this. we can say that the term "lithium silicate (barium, strontium)" is a summary comprising barium-lithium silicate, strontium-lithium silicate, and barium-strontium-lithium silicate with different proportions of barium-strontium separately or as a mixture. each of these silicates being activated with cerium and. if desired. manganese- seo
Luminescent materials obtained by the process of the invention and activated with cerium only, are specially excited by the ultra-violet radiation of 3650A and give a blue or violet color.

   materials predominantly of barium oxide as an alkaline earth component giving a blue luminescence, while those predominantly of strontium oxide as an alkaline earth component giving a luminescence approaching the color of violet. If manganese is used as an additional activator, the luminescence of the materials thus obtained is predominantly red, although some compositions produce a violet or blue luminescence. A wide range of red and blue-red shades is obtained with materials activated with both cerium and manganese. follow-

 <Desc / Clms Page number 2>

 before the variations in the compositions of the materials in a manner which will be explained below.

   In general, the color approaches red as the manganese content increases; manganese alone, in the absence of cerium. does not give noticeable luminescence to materials subjected to ultra-violet rays.



   In the preferred method of manufacturing luminescent materials according to the invention, the proportions of the starting materials are such that the molar ratio (BaO + SrO): Li2O is between 3: 1 and 1: 3 and the molar ratio ( BaO + SrO + Li2O): SiO2 is between 3: 1.7 and 3: 2'130
The amount of cerium incorporated into the starting material as an activator in the manufacture of luminescent materials according to the invention. is not critical; any proportion by weight between 1% and 20% can be used to produce irritating luminescent materials. the most intense luminescence being obtained with materials containing 5% to 10% cerium by weight.

   The manganese content is more critical and there will be no more than 5% by weight of manganese in the starting material. luminescence intensity decreasing with higher amounts of manganese o The optimum intensity seems to be obtained with an amount of manganese between 0.5% and 2% by weight, although the manganese content can be changed depending on the color luminescence to be obtained.

   Throughout the description, the proportions of activators given are the proportions in the starting materials calculated as percentages of the weight of the raw material of the final product.
Materials which are found to give red luminescence particularly useful for color correction of high pressure mercury vapor lamps have substantially the raw material composition represented by the molar ratio 1BaO: LSrO: iLi2O: 2.2SiO2. with, as activants. 10% cerium and 1% manganese; the proportion of silica in these materials can be between 2.1 and 2.2 moles.



   The luminescent color exhibited by the luminescent materials obtained by the process of the invention and containing ,. as activators., both cerium and manganese, depends on several varying factors of the composition of matter o These factors include the relative proportions of barium and strontium oxides, lithium content in relation to total alkaline content -terreux. and the silica content.



   Regarding the relative proportions of barium and strontium. it has been observed that if strontium is predominant, red luminescence tends towards violet red, and if barium is predominant, red luminescence tends towards orange-redo The different colors obtained by varying the SrO / BaO ratio are given in the following table (table I) which shows the range of colors corresponding to the materials of the following general composition
2 (Sr.Ba) O: lLi2O = 2.SiO2 activated with 81. of cerium and 2% of manganese.

 <Desc / Clms Page number 3>

 



  Io ARRAY
 EMI3.1
 
<tb> SrO <SEP> BaO <SEP> Color <SEP> of
<tb>
<tb> luminescence
<tb>
<tb>
<tb>
<tb> Proportion <SEP> molar <SEP> Proportion <SEP> molar <SEP> (radiations <SEP> 3650A)
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> 2.0 <SEP> - <SEP> Pink <SEP> purple
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> 1.5 <SEP> 0.5 <SEP> Pink <SEP> salmon
<tb>
<tb>
<tb>
<tb>
<tb> 1.0 <SEP> 1.0 <SEP> Pink <SEP> red
<tb>
<tb>
<tb>
<tb> 0.5 <SEP> 1.5 <SEP> Pink
<tb>
<tb>
<tb>
<tb> - <SEP> 2.0 <SEP> Pale pink-orange <SEP>
<tb>
 
The x-ray examination of a series of materials of which the relative propor- tions of barium oxide and strontium oxide are varied, while lithium ,,

     the silica and the activators remain constant shows that such a series of materials essentially constitutes a series of solid solutions.
When the proportion of alkaline earth metal relative to lithium is reduced for a given quantity of silica, the red generally becomes bluish, With regard to the variations of the silica content, it was found that the red color is the most pronounced in the case of materials obtained with starting materials comprising approximately 2 moles of silica per 3 moles of alkaline earth metal + lithium, the color tending towards violet or blue with the maximum proportions of silica,

   and giving a slightly increased yellow emission when the proportion of silica drops below about 2 moles.
The variations in the cerium content seem to have little effect on the color and simply influence the intensity of the luminescence as mentioned above while, as already explained, the color becomes more and more red as the manganese content increases.



   The following table (Table II) gives the luminescence color changes of the general starting materials 1BaO g lSrO: lLi2O:: 2.2SiO2. when the proportions of cerium and manganese vary:

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 TABLE II.
 EMI4.1
 
<tb>% ce <SEP>% Mn <SEP> Color <SEP> of <SEP> the <SEP> luminescence
<tb>
<tb>
<tb>
<tb> (<SEP> deletions from <SEP> 3650)

  
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> 5 <SEP> 0 <SEP> Blue
<tb>
<tb>
<tb>
<tb> 5 <SEP> 0.5 <SEP> Dark pink <SEP>
<tb>
<tb>
<tb>
<tb> 5 <SEP> 1.0 <SEP> Pink <SEP> red
<tb>
<tb>
<tb>
<tb> 5 <SEP> 1.5 <SEP> Pink <SEP> red
<tb>
<tb>
<tb>
<tb> 5 <SEP> 2.0 <SEP> Pink <SEP> red
<tb>
<tb>
<tb>
<tb> 5 <SEP> 5.0 <SEP> Red
<tb>
<tb>
<tb>
<tb> 10 <SEP> 0 <SEP> Blue
<tb>
<tb>
<tb>
<tb> 10 <SEP> 0.5 <SEP> Dark pink <SEP>
<tb>
<tb>
<tb> 10 <SEP> 1.0 <SEP> Pale pink-red <SEP>
<tb>
<tb>
<tb>
<tb> 10 <SEP> 1.5 <SEP> Rose-red
<tb>
<tb>
<tb>
<tb> 10 <SEP> 2.0 <SEP> Red
<tb>
<tb>
<tb>
<tb> 10 <SEP> 5.0 <SEP> Red
<tb>
<tb>
<tb>
<tb> 15 <SEP> 0 <SEP> Blue
<tb>
<tb>
<tb>
<tb> 15 <SEP> 0.5 <SEP> Pink <SEP> purple
<tb>
<tb>
<tb>
<tb> 15 <SEP> 1.0 <SEP> Pink <SEP> pale red <SEP>
<tb>
<tb>
<tb>
<tb> 15 <SEP> 1.5

  <SEP> Rose <SEP> red
<tb>
<tb>
<tb>
<tb> 15 <SEP> 2.0 <SEP> Pink <SEP> red
<tb>
<tb>
<tb> 15 <SEP> 5.0 <SEP> Red
<tb>
 
It goes without saying that the color names mentioned in the description and in the tables are only for comparison, and that it is extremely difficult, if not impossible. describe with precision the large range of colors obtainable with the series of luminescent materials of the invention;
The following table (Table III) indicates the mutual effects of variations in the proportions of silica. of cerium and manganese on the color of the luminescence of materials with molar ratio BaO SrO:

   Li20 equal to 1: 1: 1, excited by radiation at 365Oa wavelength

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 EMI5.1
 
<tb> SiO2 <SEP> 0.5% <SEP> Manganese <SEP> Manganese
<tb> (moles) <SEP> 0.5% <SEP> Manganese <SEP> 1% <SEP> Manganese <SEP> 1.5% <SEP> Manganese
<tb> il-Ce <SEP> 51-Ce <SEP> 10 '/ 0 <SEP> Ce <SEP> $ 15 Ce <SEP> 2 <SEP> 0' / 0 <SEP> Ce <SEP> 1% Ce <SEP> 5% Ce <SEP> 10% Ce <SEP> 151-Ce <SEP> 20 '/ 0 <SEP> Ce <SEP> 1% Ce <SEP> 5% Ce <SEP> lOCe <SEP> 15% This <SEP> 20% This
<tb> 2.2 <SEP> Rose <SEP> Rose <SEP> Rose <SEP> Rose <SEP> Rose <SEP> Shave <SEP> Rose <SEP> Rose <SEP> Rose <SEP> Rose <SEP> Rose <SEP > Rose <SEP> Rose <SEP> Rose <SEP> Rose
<tb> dark <SEP> dark <SEP> dark <SEP> salmon <SEP> salmon <SEP> red <SEP> red <SEP> red <SEP> red <SEP> salmon <SEP> red <SEP> Red <SEP > red <SEP> red <SEP> red
<tb> purple <SEP> purple <SEP> pale <SEP> pale

  <SEP> dark
<tb> 2.1 <SEP> Poupre <SEP> Pink <SEP> Pink <SEP> Lilac <SEP> Lilac <SEP> Pink <SEP> Pink <SEP> Pink <SEP> Pink <SEP> Pink <SEP> Pink <SEP > Rose <SEP> Rose <SEP> Rose <SEP> Rose
<tb> dark <SEP> salmon <SEP> pale <SEP> dark <SEP> red <SEP> red <SEP> red <SEP> pale <SEP> dark <SEP> red <SEP> red <SEP> red <SEP > red
<tb> purple <SEP> pale <SEP> pale <SEP> pale
<tb> 2.0 <SEP> Purple <SEP> Pink <SEP> Lilac <SEP> Lilac <SEP> Lilac <SEP> Pink <SEP> Pink <SEP> Pink <SEP> Pink <SEP> Pink <SEP> Pink <SEP > Rose <SEP> Rose <SEP> Rose <SEP> Rose
<tb> sonbre <SEP> pale <SEP> pale <SEP> dark <SEP> red <SEP> salmon <SEP> salmon <SEP> salmon <SEP> red <SEP> red <SEP> red <SEP> red <SEP > salmon
<tb> pale <SEP> pale <SEP> pale <SEP> pale <SEP> pale <SEP> pale
<tb> 1.9 <SEP> Purple <SEP> Lilac <SEP> Lilac <SEP> Lilac <SEP> Lilac <SEP> Pink

  <SEP> Rose <SEP> Rose <SEP> Rose <SEP> Rose <SEP> Rose <SEP> Rose <SEP> Rose <SEP> Rose <SEP> Rose
<tb> pale <SEP> pale <SEP> pale <SEP> pale <SEP> dark <SEP> salmon <SEP> salmon <SEP> salmon <SEP> salmon <SEP> red <SEP> red <SEP> salmon <SEP > salmon <SEP> dark <SEP>
<tb> pale <SEP> pale <SEP> pale <SEP> pale <SEP> pale
<tb> 1.8 <SEP> Purple <SEP> Lilac <SEP> Lilac <SEP> Lilac <SEP> Lilac <SEP> Pink <SEP> Pink <SEP> Pink <SEP> Pink <SEP> Pink <SEP> Pink <SEP > Rose <SEP> Rose <SEP> Rose <SEP> Rose
<tb> pale <SEP> pale <SEP> pale <SEP> pale <SEP> dark <SEP> salmon <SEP> salmon <SEP> salmon <SEP> salmon <SEP> red <SEP> red <SEP> salmon <SEP > salmon <SEP> salmon <SEP>
<tb> pale <SEP> pale <SEP> pale <SEP> pale <SEP> pale <SEP> pale
<tb>
 

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Luminescent materials manufactured according to the process of the invention have

  good thermal stability and since they are brought to luminescence under ultraviolet radiations 3650A wavelength, they are particularly useful in fluorescent discharge lamps with high pressure mercury vapor, especially for correcting the light color of the mercury vapor discharge; For this correction, red fluorescent and blue fluorescent materials are suitable.



  In these lamps, the materials of the invention can be applied in the form of a layer covering the inner wall of a glass bulb surrounding the envelope where the discharge takes place, as usual with this kind of lamp. lamps.



   The materials produced according to the invention can however also be used in low pressure fluorescent lamps and for fluorescent screens of cathode ray tubes.



   In the manufacture of luminescent materials according to the invention, the preferred starting raw materials are barium and strontium carbonates, lithium nitrate or carbonate, silica, cerium oxide or nitrate and a manganese chloride or carbonate. The starting materials are mixed thoroughly, for example by grinding, and the mixture is heated for a period of one to five hours at a suitable temperature, for example between 700 ° C and 10,000 ° C.

   It is believed that heat treatment in a reducing amphosphere provides for the incorporation of cerium in the trivalent state. The preferred reducing atmosphere is hydrogen, and experience has shown that it is generally desirable to carry out the treatment. thermal in two or more stages, the material being reground after each stage, in order to obtain the optimum luminescence properties.



   Preferably, in order to obtain a complete reaction between barium and / or strontium, lithium and silicon compounds, these compounds are preheated together in air at a temperature of 700 C to 800 C before the addition of the cerium compounds. and manganese; to complete the production of the luminescent material, this preheating is followed, after the addition of the activators.

   one or more other stages of heating, usually at higher temperatures o It will be appreciated that materials containing only alkaline earth, i.e. barium oxide or strontium oxide , generally require a longer heat treatment for the complete reaction, than materials containing both strontium oxide and barium oxide.
Materials containing only barium oxide or strontium oxide must undergo, after addition of the activators, a heat treatment lasting a total of at least 3 hours.
It goes without saying that the materials used in the manufacture of the luminescent materials of the invention must have a high degree of purity.

   as always in this manufacture. The strontium carbonate used is preferably prepared by precipitation from solutions of strontium chloride and ammonium carbonate.



   According to a preferred method of preparing strontium carbonate given by way of example, 1.867 kg of strontium chloride are dissolved in 3 liters of distilled water and 0.672 kg of ammonium carbonate also in 3 liters of distilled water. . These solutions are filtered and the strontium chloride solution is slowly added to the ammonium carbonate solution which is constantly stirred. The resulting precipitate and mother liquor are kept standing for two hours before filtering, and the precipitate. is then washed thoroughly and dried at 200 C.



   Certain specific processes according to the invention for the production of luminescent materials are described below by way of example. The materials are obviously all crushed and passed through a sieve, before

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 use, after final heat treatment.



   Examples 1 to 4 describe the preparation of materials containing varying relative proportions of barium oxide and strontium oxide, the lithium and silica contents remaining constant. Examples 5 to 10 inclusive show the effect obtained by varying the proportion of alkaline earth to lithium, the ratio of barium oxide to strontium oxide being kept constant at 1: 1. The materials of Examples 11 and 12 have only barium oxide as an alkaline earth. and its proportion varies with respect to lithium. Finally, Examples 13 to 15 show the effect of varying the silica content, the BaO SrO: Li2O proportions being kept constant at 1: 1: 1.



  EXAMPLE l.-
To obtain a luminescent material with a total composition of lBaO: lSrO lLi20: 2.2SiO2 activated with 10% cerium and 1% manganese, the following mixture of materials is used;
 EMI7.1
 
<tb> Carbonate <SEP> of <SEP> barium <SEP> (BaC03) <SEP> 47 <SEP> gro
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Carbonate <SEP> of <SEP> strontium <SEP> (SrC03) <SEP> 35 <SEP> gro
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Carbonate <SEP> of <SEP> lithium <SEP> (Li2CO3) <SEP> 17.6 <SEP> gro
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Silica <SEP> (sio2) <SEP> 31.5 <SEP> gro
<tb>
 
Barium and lihtium carbonates are the purest obtainable,

   and lithium carbonate is passed through a ball mill to reduce the particle size. The strontium carbonate is prepared as above and the silica used herein and in all other examples is "Kallinckrodt" grade. specially manufactured for the manufacture of luminescent materials The silica "Mal- linckrodt" contains a proportion of water.-but the amounts given in the various examples are the amounts of pure and dehydrated SiO 2
The above mixture is lightly ground and carried, for two hours,

   at 800 C in open silica crucibles o After cooling. the treated mixture is reground and mixed with 12.3 gro of cerium oxide CeO2. and a solution of 3.6 g of manganous chloride McCl24H2O in 100 ml of distilled water. The paste thus obtained is dried at 200 c. the dry matter is again mixed thoroughly and brought to 900 C in silica tubes, in a hydrogen atmosphere, for one hour o It is left to cool in hydrogen, rebroled and reheated to 900 C for another hour; the grinding and heating operations are repeated until optimum luminescence is obtained; three heat treatments are usually sufficient.



   The product gives an intense pink-red fluorescence under ultraviolet radiation at wavelength 3650A. A material prepared in this manner was examined by x-ray and was found to consist essentially of a single phase. Table IV gives the interplanar spacings (d) and the relative intensities of twelve main x-ray reflections. These data were obtained by the method of X-ray analysis described in the pamphlet No. E43-49T published in 1942 by the American Society for the Testing of Materials, and revised in 1946 and 19490 Interplanar spacings have not been corrected for absorption.

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  TABLE IV
 EMI8.1
 
<tb> d () <SEP> Relative <SEP> intensities
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> 4.718¯ <SEP> 0.005 <SEP> low
<tb>
<tb>
<tb>
<tb> 4.047 <SEP> "<SEP> low-medium
<tb>
<tb>
<tb>
<tb> 3.671 <SEP> medium
<tb>
<tb>
<tb> 3.427 <SEP> "<SEP> low-medium
<tb>
<tb>
<tb>
<tb> 3.319 <SEP> "<SEP> low-medium
<tb>
<tb>
<tb> 3.000 <SEP> "<SEP> low-medium
<tb>
<tb>
<tb>
<tb> 2.905 <SEP> "<SEP> strong
<tb>
<tb>
<tb> 2.819 <SEP> very <SEP> strong
<tb>
<tb>
<tb>
<tb> 2.391 <SEP> "<SEP> medium
<tb>
<tb>
<tb>
<tb> 2.313 <SEP> "<SEP> medium
<tb>
<tb>
<tb> 2.021 <SEP> "<SEP> medium
<tb>
<tb>
<tb>
<tb> 1.932 <SEP> "<SEP> low-medium
<tb>
 
This phase has also been observed in other materials of the invention examined by x-ray.

   sometimes in association with a second phase which has not yet been fully studied.



  EXAMPLE 2.-
To obtain a lithium strontium silicate with a total composition of 2Sr0 lLi2O: 2.2SiO2 with 8% cerium and 2% manganese, the following ingredients are used:
 EMI8.2
 
<tb> Carbonate <SEP> of <SEP> strontium <SEP> (srCO3) <SEP> 20.1 <SEP> gr.
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>



  Lithium <SEP> nitrate <SEP> <SEP> (LiNO33H2O) <SEP> 16.6 <SEP> gro
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Silica <SEP> (SiO2) <SEP> 8.9 <SEP> gr
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Nitrate <SEP> of <SEP> cerium <SEP> [Ce (NO3) 3.6H2O] <SEP> 7.7 <SEP> gro
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Carbonate <SEP> of <SEP> manganese <SEP> (MnC03) <SEP> 1.05 <SEP> gro
<tb>
 
Strontium carbonate, lithium nitrate and de nitrate. cerium are of the commercially pure type, strontium carbonate is prepared as above and manganese carbonate is obtained by precipitation from solutions of manganese chloride and ammonium carbonate.



   The above finely divided and mixed materials are brought to 900 ° C. for one hour in a hydrogen atmosphere, then cooled in hydrogen, regrind, reheated for one hour at 900 G in hydrogen, and cooled to one hour. again in hydrogen.



   The material thus prepared gives an intense salmon-pink violet fluorescence under ultra-violet radiation of 3650 Å wavelength.



  EXAMPLE 3.-
To obtain a lithium barium silicate having the total composition 2BaO 1Li2O: 2.2SiO2. activated by 8% cerium and 2% manganese.

 <Desc / Clms Page number 9>

 we start from the following mixture
 EMI9.1
 
<tb> Carbonate <SEP> of <SEP> barium <SEP> (BaC03) <SEP> 211 <SEP> gro
<tb>
 
 EMI9.2
 Lithium nitrate (LiNoo3Ho) 13.3 gro Silica (S102) 70 gro Cerium nitrate Ce (N03) 3 a6HZO 7..7 gro
 EMI9.3
 
<tb> Carbonate <SEP> of <SEP> manganese <SEP> (MnCO3) <SEP> the <SEP> 05 <SEP> gro
<tb>
 
These materials are similar to those used in the previous exampleso
The mixture is treated as in Example 2. and the product obtained gives an intense fluorescence of a pale pink-orange color under ultra-violet radiations of wavelength 3650A.



  EXAMPLE 4.-
To obtain a material having the total composition
 EMI9.4
 14BaO: 1 o 6Sro ô 1Li20 = 2 <i2Sl (L and activated by 1 ± µi of cerium and 1% of manganese. We start with the following mixture of powders packed by shaking:.
 EMI9.5
 
<tb> Carbonate <SEP> of <SEP> barium <SEP> (BaCO3) <SEP> 157 <SEP> gro
<tb>
 
 EMI9.6
 Strontium carbonate (Sroo.) 505 gr.

   Lithium carbonate (Li 2Co3) 42 gr.
 EMI9.7
 
<tb> Silica <SEP> (SiO2) <SEP> 75 <SEP> gro
<tb>
 
This mixture is heated for two hours at 750 C in an open silica crucible
The treated powder is ground with 30.75 g of cerium oxide and made into a paste with 200 cc of an aqueous solution of manga chloride.
 EMI9.8
 neux (comprising z04 gro of MnCi Z-H-O) This paste is dried in an oven at 250 C and then ground. and the powder obtained is heated, in a tube
 EMI9.9
 silica in a hydrogen atmosphere at 8000C for one hour, well at 8250C for another hour. and finally at 8750C for a third hour. After each heat treatment, the product is cooled in hydrogen.

   then ground again
The powder obtained after grinding and sieving is a final product giving a good orange-pink fluorescence under the radiations of 3650 Ao EXAMPLE 5.-
To obtain a silicate of barium, strontium, lithium of com-
 EMI9.10
 total position Oa9BaO: â Oa9Sr0 s la2Li20 s 2a2Si02 activated by 10, cerium and 1% manganese, we start with the following mixture
 EMI9.11
 Barium carbonate (BaC03) llnl gro Strontium carbonate (srC 3) 8.3 gro Lithium carbonate (LizC03) 5a55 gr.

   
 EMI9.12
 
<tb> Silica <SEP> (Sio2) <SEP> 8.25 <SEP> gr.
<tb>
<tb> Cerium <SEP> <SEP> <SEP> <SEP> (Ce <SEP> 02 <SEP>) <SEP> 3.07 <SEP> gro
<tb>
 
 EMI9.13
 Manganese chloride (MnC1204H20) 0 9 gro

 <Desc / Clms Page number 10>

 
The materials are all of commercially pure type and are similar to those used in the previous examples.
The manganese chloride is dissolved in 35 cc.

   of distilled water and this solution, added to the other constituents, constitutes a paste of all finely divided materials, which is dried in an uncovered basin placed in an oven at 200 ° C.
The dried material is crushed and heated in a silica tube, in a hydrogen atmosphere at 875 C for one hour, then cooled in hydrogen for half an hour, reground and reheated in hydrogen. at 900 C for one hour and cooled again in hydrogen.



   The material thus prepared gives an intense fluorescence of pink color under ultraviolet radiation of 3650A wavelength.



  EXAMPLE 6.-
To obtain a barium silicate, strontium. lithium with total composition ,, 0.75BaO $: 075SrO: 1.5Li2O: and activated by 2.2Sio2 of cerium and 10% of manganese, we start from the following mixture
 EMI10.1
 
<tb> Carbonate <SEP> of <SEP> barium <SEP> 1% <SEP> 10.0 <SEP> gr.
<tb>
<tb>



  Strontium <SEP> carbonate <SEP> <SEP> (BaCO3) <SEP> 7.5 <SEP> gr.
<tb>
<tb>



  Lithium <SEP> carbonate <SEP> <SEP> (SrCO3) <SEP> (Li2CO3) <SEP> gro
<tb>
<tb> Silica <SEP> 7.5 <SEP> (SiO2) <SEP> gro
<tb> Oxide <SEP> of <SEP> cerium <SEP> 8.94 <SEP> (CeO20 <SEP> gr.
<tb>
<tb>



  Manganese <SEP> Chloride <SEP> 3.07 <SEP> 0.9 <SEP> gro
<tb>
 
The materials used and the method of mixing and heat treatment are the same as in Example 50 The product obtained gives an intense pink fluorescence under radiations of (MnCl2.4H2O) $ 365O o EXAMPLE 7. -
To obtain a material with a total composition of 1.15BaO: 1.15SrO: 0.7Li2O: 42.2SiO2. activated by 10% cerium and 1% manganese. we start from the following mixture of powders packed by shaking
 EMI10.2
 
<tb> Carbonate <SEP> of <SEP> barium <SEP> (BaCO30 <SEP> 126 <SEP> gr.
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>



  Strontium <SEP> carbonate <SEP> <SEP> (srCO3) <SEP> 95 <SEP> gr
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Carbonate <SEP> of <SEP> lithium <SEP> (Li2CO3) <SEP> 29 <SEP> gr
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Silica <SEP> (siO2) <SEP> 74 <SEP> gr.
<tb>
 



   This mixture is heated, in an open silica crucible, for two hours at 750 C.
The treated powder is ground with 30.75 gr of cerium oxide. and we make a paste by adding 200 cc of manganous chloride (containing 9.04 gr. of MnCL24H2O). This paste is dried in an oven at 250 G, then ground and the powder obtained is heated in a silica tube.

   in a hydrogen atmosphere, for one hour at 875 C and for another hour at 900 C

 <Desc / Clms Page number 11>

 
 EMI11.1
 After each heat treatment "the product is cooled in hydrogen and regrind
The powder obtained after grinding and sieving of the final product., Gives a moderate pink fluorescence under the radiations of 3650 Ao EXAMPLE 80-
 EMI11.2
 A material of total composition 0.5BaO 9 0.5SrO 8 2L120 is prepared:

   m 2pSifl activated with 10% cerium and 1% manganese, according to a process similar to that of example 49, starting from the following ingredients g
 EMI11.3
 
<tb> Carbonate <SEP> of <SEP> barium <SEP> (BaC03) <SEP> 77 <SEP> gr
<tb>
 
 EMI11.4
 Strontium carbonate (srco3) 575 gr
 EMI11.5
 
<tb> Carbonate <SEP> of <SEP> lithium <SEP> (Li2CO3) <SEP> 116 <SEP> gr
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Silica <SEP> (SiO2) <SEP> 103 <SEP> gro
<tb>
 
After addition of cerium oxide and manganous chloride.

   the heat treatment takes place in three stages, in hydrogen at respective temperatures of 875 C 900 C and 925 Co
The powder obtained after grinding and sieving of the final product gives a moderate salmon-pink fluorescence under the radiation of 3650Ao EXAMPLE 9.-
 EMI11.6
 A material of total composition 0.25BaO s 0.25SrO 1 2a5Ll-0 2,, 2SiO 2 '<activated with 10 cerium and 1% manganese ,, is prepared according to a process similar to that of FIG. 4, starting from the materials the following:

     
 EMI11.7
 Barium carbonate (BaC03) 45 to 6 gr
 EMI11.8
 
<tb> Carbonate <SEP> of <SEP> strontium <SEP> (SrCO3) <SEP> 34 <SEP> gr
<tb>
<tb> Carbonate <SEP> of <SEP> lithium <SEP> (Li2CO3) <SEP> 171 <SEP> gr
<tb>
<tb> Silica <SEP> (SiO2) <SEP> 122 <SEP> gro
<tb>
 
After addition of cerium oxide and manganous chloride. the heat treatment takes place in three stages, in hydrogen at
 EMI11.9
 respective temperatures of 8500C., 8750C and 9000C.



   The powder obtained after grinding and sieving of the final product gives a moderate lilac fluorescence under the radiation of 3650 Ao EXAMPLE 100-
 EMI11.10
 A material of total composition 1.25BaO s 1a25 SrO g 0a5Li0 2D2Sï0Z, activated by 1C. cerium and 1% manganese is prepared according to a process similar to that of Example 4.

   starting from the following subjects
 EMI11.11
 
<tb> Carbonate <SEP> of <SEP> barium <SEP> (BaC03) <SEP> 131 <SEP> gr
<tb>
 
 EMI11.12
 Strontium carbonate (StLCr3) 98 gr Lithium carbonate (Li 2003) 19.8 gr Silica (S'02) 70.5 gro

 <Desc / Clms Page number 12>

 
After addition of the oxides of cerium and manganous chloride. the heat treatment takes place in three stages, in hydrogen at temperatures
 EMI12.1
 respective peratures of 90C C 92500 and 950 Co La- powder obtained after grinding and sieving of the final product gives a moderate pink fluorescence under:

  365O radiations EXAMPLE 11.-
To prepare a lithium barium silicate of composition
 EMI12.2
 total 1.2BaO g 1.8Li20, s 2.2S10- activated by lcfi of cerium and 1% of manganese. a mixture having the following composition is used
 EMI12.3
 Barium carbonate (BaC03) 16.0 gr Lithium carbonate (L2CO3) 9n0 gr
 EMI12.4
 
<tb> Silica <SEP> (Si02) <SEP> 8.94 <SEP> gr
<tb>
 
 EMI12.5
 Cerium oxide (08 2) 3007 gr Manganese chloride (MnG124H2 0) On9 gro
The materials and the method of preparation and heat treatment of the mixture are the same as in Example 50
The material obtained gives an intense pale pink fluorescence under the effect of radiation of 3650Ao EXAMPLE 12-
To prepare a lithium barium silicate of composition to-
 EMI12.6
 tale Lao 1 2Ll0 g 2,2SIO2,

   and activated by 1C% cerium and manganese, a mixture is used having the following composition
 EMI12.7
 Barium carbonate (BaG03) 14a3 gro Lithium carbonate (Li2003) l0n 'gara Silica (LO2) 9ar] 5 gr Cerium oxide (Ceo2) 3.07 gr Manganese chloride (MnC12 4I! 20) osa9 gro
The materials used and the method of preparation and heat treatment of the mixture are the same as in Example 5.

   The material obtained gives a good pale pink fluorescence under the excitation of 365O radiation. EXAMPLE 13.-
To prepare a material of total composition lBaO
 EMI12.8
 ISrO: lLi20 g 23i02 "activated by 1C% cerium and 1.2% manganese .. we start with the following mixture of powders packed by shaking:

   
 EMI12.9
 
<tb> Carbonate <SEP> of <SEP> barium <SEP> (BaCO3) <SEP> 121 <SEP> gr
<tb>
 
 EMI12.10
 Strontium carbonate (srC 3) 90n5 gr
 EMI12.11
 
<tb> Carbonate <SEP> of <SEP> lithium <SEP> (Li2CO3) <SEP> 45n4 <SEP> gr
<tb>
<tb> Silica <SEP> (Si02) <SEP> 74 <SEP> gro
<tb>
 
This mixture is heated for two hours at 750 C in an open silica crucible.
The treated powder is ground with 30a75 g of erium oxide and made into a paste by the addition of 200 cc of an aqueous solution of
 EMI12.12
 manganous chloride (comprising 10n 8 gr of 1I.fnC124H20) 0 This paste is se-

 <Desc / Clms Page number 13>

 ched in an oven at 250 C then ground, and the powder obtained is heated in a silica tube ,,, in a hydrogen atmosphere,

   for one hour at 850 C another hour at 875 C and a third hour at 900 C After each heat treatment, the product is cooled in hydrogen and ground.
The powder obtained after grinding and sieving the final product gives an intense pale salmon pink fluorescence. under the radiations of 365 EXAMPLE IL .. 0-
To prepare a material with a total composition lBaO: lSrO: lLi2O: 1.8 SiO2 activated by 10% cerium and 1% manganeseon starts with the following mixture of powders packed by shaking:

   
 EMI13.1
 
<tb> Carbonate <SEP> of <SEP> barium <SEP> (BaC03) <SEP> 125 <SEP> gr
<tb>
<tb> Carbonate <SEP> of <SEP> strontium <SEP> (srCO3) <SEP> 93.5 <SEP> gr
<tb>
<tb> Carbonate <SEP> of <SEP> lithium <SEP> (Li2CO3) <SEP> 47 <SEP> gr
<tb>
<tb> Silica <SEP> (Sio2) <SEP> 68.5 <SEP> gro
<tb>
 
The mixture is brought to 700 C for two hours. in an open silica crucible
The treated powder is ground with 30n75 g of cerium oxide and made into a paste by adding 200 cc of an aqueous solution of manganous chloride (containing 9.04 g of MnCL24H2O).

   This paste is dried in an oven at 250 ° C. and then ground and the powder obtained is heated in a silica tube. in a hydrogen atmosphere for one hour at 800 ° C. then for one hour at 850 ° C. and finally for one hour at 875 ° C. After each heat treatment, the product is cooled in hydrogen and reground.



   The powder obtained, after grinding and sieving of the final product. gives a good pale salmon pink fluorescence under 365O radiation EXAMPLE 15.-
To prepare a material of total composition lBaO: lSrO: lLi2O: 2.lSiO2 activated by 10% cerium and 1% manganese, we start from the following pouares mixed by light grinding
 EMI13.2
 
<tb> Carbonate <SEP> of <SEP> barium <SEP> (BaC03) <SEP> 239 <SEP> gr
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Carbonate <SEP> of <SEP> strontium <SEP> (SrCO3) <SEP> 179 <SEP> gr
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Carbonate <SEP> of <SEP> lithium <SEP> (Li2CO3) <SEP> 896 <SEP> gr
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Silica <SEP> (SiO2)

   <SEP> 153 <SEP> gr
<tb>
 
This mixture is brought to 7500C for two hours in an open silica crucible.
The treated mixture is ground with 61.5 g of cerium oxide, and transformed into a paste by adding thereto a solution of 18 g of manganous chloride (MnCL24H2O) in 500 cc of distilled water. This paste is heated in an oven at 200 Ce then ground, and the powder obtained is heated in a silica tube, in a hydrogen atmosphere * for one hour at 900 C. another hour at 915 C. and a third hour at 915 C. Co After each heat treatment the product is cooled in hydrogen and regrind
The powder obtained after grinding and sieving of the final product gives an intense pink-red fluorescence under the radiations of 365O


    

Claims (1)

R E S U M Eo The invention relates to a method of manufacturing a luminescent material, characterized in that a mixture of barium oxide and / or strontium oxide, lithium oxide is heated in a reducing atmosphere. thium and silica .. or compounds giving these oxides by decomposition during heating, the relative proportions of these oxides and / or compounds used being such that the molar proportion (BaO + SrO): Li2O is in the range 5 if at 1: 5 and the molar proportion (BaO + srO + Li 2 0): SiO2 is in the range 3 if at 1: 1 with a cerium compound so as to produce a lithium silicate (barium, strontium) activated with cerium, which can be excited to luminescence by ultra-violet radiations of 365O The process of the invention may also include the following features, separately or in combination. 1. The starting mixture also contains a manganese compound which acts as an additional activator of the luminescent material obtained. The proportions of the starting materials are such that the molar ratio (BaO + SrO: Li2O present is between 3: 1 and 1: 3. And the molar ratio (BaO + SrO + Li2O); sio2 present is between 3 if . 7 and 3: 2.3. 3. The proportion of cerium present in the starting material is in the range of 1% to 20% by weight of the raw materials of the product. 4. The proportion of cerium present in the starting material is between 5% and 10% by weight of the raw materials of the product. 5. The manganese contained in the starting material does not exceed 5% by weight of the raw materials of the product. 60 The manganese contained in the starting material is between 0.5% and 2% by weight of the raw materials of the product. 7. The starting material is barium carbonate and / or barium carbonate. lithium nitrate or carbonate, silica, an oxide or nitrate of cerium and. if desired. manganeseo chloride or carbonate 8. The mixture is heated to 700 C to 1000 C for a total period of 1 to 5 hours. 9. The reducing atmosphere used is hydrogen. 10. The heating takes place in two or more stages, the material being reground between each stage. 11 Oxides or other compounds of barium and / or strontium, lithium and silicon are first heated together in air. at a temperature of 700 C to 800 C and heat treatment with the cerium compound and optionally the manganese compound suito The invention also relates to luminescent materials produced by the method described. The invention also relates to the combinations of a luminous material produced by the process described with electrical devices suitable for bringing it to luminescence, and in particular the following devices for electrical discharge: the Mercury vapor electrical discharge lamp under high pressure containing such luminescent material arranged so as to be <Desc / Clms Page number 15> excited to luminescence when an electric discharge occurs in the lamp 2. Low pressure mercury vapor electric discharge fluorescent lamp containing such luminescent material so arranged as to be excited to luminescence when an electric discharge occurs in the lamp. 3. A cathode ray tube containing such a luminescent material arranged so as to be excited to luminescence by the cathode rays produced by the tube in operation.