FI65796C - JORDALKALI-TIOGALLATBASERAD SJAELVLYSANDE SUBSTANS SAMT FOERFARANDE FOER FRAMSTAELLNING DAERAV - Google Patents

Description

RSFH [»] ADJUSTMENT PUBLICATION 6579 6 jgTjft l J * 'UTLÄGGNI NGSSKMFT O ϋ f s Ό 5¾¾ c Patent aySnaetty 10 07 1934

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France-France (FR) 7835330 (71) Rhöne-Poulenc Industries, 22, Avenue Montaigne, 75008 Paris (8eme), France-France (FR) (72) Patrick Oougier, Marly-le-Roi, France-France ( FR) (74) Berggren Oy Ab (54) Self-illuminating substance based on alkaline earth thiogalate and method for its preparation - Jordalkali thiogallat base based on the same properties as the fragrant substance

The present invention relates to novel self-casting agents and a process for their preparation; the invention relates in particular to alkali-alkaline earth thiogallates activated by europium.

Alkali-activated alkaline earth thiogallates are already known from the prior art. Thus, for example, French Patent 2,054,602 discloses compounds represented by the formula:

R 1 -w Ga 2 S 4: \ where R is at least one alkaline earth metal and A is selected from the group consisting of europium, lead and calcium and w is a number selected to provide the desired luminescence upon brief exposure to the compound. These prior art compositions are cathodiluminescent and photoluminescent and have a wide colored emission field spanning the entire visible spectrum. Trivalent calcium, strontium, and barium thiogallates activated by divalent europium emit, or emit, in the yellow, green, and blue-green regions.

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Also known from the prior art is a self-illuminating composition of matter / zinc silicate activated with di- 2+ manganese and having the formula Zn2 Si 04: Mn, and is most commonly known as Jedec P 1 powder.

This Jedec P 1 powder and the thiogallates described in the above-mentioned patent publication can both be used in cathode-luminescent multicolor image surfaces. Thanks to the chromaticity of Jedec P 1 powder, the color reproduction capacity in these systems and the fullness of the emission colors can be increased. In contrast, its intensity is insufficient and the continuity of splendor may be disturbing in some of its applications.

The aforementioned europium-activated thiogallates contain a mixture of substances with almost the same chromaticity as Jedec P 1 powder. Compared to the latter, they have the advantage of a relatively short continuity of splendor (self-illumination lasts only after a very short moment of excitation stimulation has ceased). However, the main disadvantage of this type of substance is its insufficient potency in most applications.

It is an object of the present invention to provide a mixture of substances having good chromaticity, short continuity and high emissivity.

The invention therefore relates to a new self-illuminating compound which is characterized in that it corresponds to the general formula, M1-y MV 1-a · a <Gal-z Βζ »2Ί xl« a! Eud <X) wherein M represents at least one alkaline earth element selected from the group consisting of Ca, Sr and Ba y is greater than or equal to 0 and less than or equal to approximately 0.7 (0.0 ^ y ^ 0.7)

a is greater than or equal to approximately 0.8 and something other than 1 when y = O

z is greater than or equal to O and less than or equal to y (0 ^ z ^ y) X represents sulfur or a mixture of sulfur and oxygen, and 3 65796 d is a number selected so as to produce the desired luminescence when self-illuminating. excitation energy is applied to the substance for a short time.

Another aspect of the invention is a substance as defined above wherein: y is greater than or equal to about 0.10 and less than or equal to about 0.50 (0.10 <y ^ 0.50) a = 1 z = y and d range from about 0.005 to about 0.20.

According to a particular embodiment of the invention, M Srl-xBax 3a 0 ^ x ^ 1 ·

Another object of the invention is a self-illuminating substance corresponding to the formula:? Sr0.8 Ba0.2) 0.65 MgO.35 / 0.98 (GaO, 65 ^, 35 ^ X4: Eu0.02 -

The invention also relates to a process for the preparation of the compounds of the formula I, which comprises carrying out at least one thermal treatment in a sulfurizing medium at a temperature of about 700 ° C to about 900 ° C for a compound mixture containing at least one alkaline earth, gallium, boron and europium.

These compounds are preferably selected from oxides, sulfides, carbonates or chlorides.

The sulfurizing medium preferably consists of a stream of H2S.

According to a special implementation, work is carried out in the presence of carbon in such a way as to supplement the reduction by means of europium from the trivalent state to the divalent state. This is done in practice by putting the various compounds in a charcoal container (nacelle en Carbone).

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The compounds of formula I according to the invention, in which M represents calcium, emit a yellow-green area.

Compounds in which M represents strontium emit in the green region.

When M represents barium, emission occurs in the green-blue region.

The phosphor according to the invention can be used in posters with a cathodiluminescent monochromatic or multicolor image surface and to make graphic, alphanumeric and other information visible to the eye. They can be used either alone in applications where their emission color is as desired, especially in oscilloscopes, or as a primary component in monochrome and multicolor image surfaces, and in particular in so-called in penetration tubes and black and white and color television tubes.

By means of photon excitation, the materials according to the invention can be used in colored systems which correspond to their own radiation or to correct color. By way of example, fluorescent lamps and tubes may be mentioned without limitation.

It should be noted that for all the compounds of formula I according to the invention, the typical physical properties of the radiation by cathode excitation are identical to those obtained by photon excitation.

When M represents more than one alkaline earth metal, an intermediate color is obtained which is between green-yellow and green-blue. For green, chromaticity is most preferred when M is Sr and Ba at 80% Sr and 20% Ba. It is precisely by using this compound as the green component on the multicolor image surface of the television in combination with the phosphor, usually used as the blue component 3+ (ZnS: Ag) and the red component (Y2 O2 S: Eu), that can be obtained with prior art thiogallates. .

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As will be shown below, the compounds of the invention have an important advantage over prior art thiogallates in providing stronger radiation. Another, equally important advantage in economic terms is that the compounds of the invention require a smaller amount of gallium, which is a very expensive substance.

Other advantages of the compounds of the invention include radiation resistance at high current densities of cathode excitation; this represents a particular advantage in that the resolution of television images can be improved by reducing the jet diameter of the excited electrons. Mention may also be made of the possibility of using the excitation and radiation at points in the spectrum to transition from calcium to strontium, then barium, in order to generate light cascades suitable for the transition of the spectrum from short to longer wavelengths. In particular, it is a matter of adjusting the instantaneous radiation to the response of the photodetector, which is known to have sensitivity maxima located at wavelengths at the upper limits of the visible spectrum.

Other typical physical properties and advantages of the invention will become more apparent upon reading the following examples, which should in no way be construed as limiting the invention.

Example 1

Preparation of a compound of the invention having the formula; (Ai) r ^ Sr0.80 Ba0.20) 0.65 Mg0.35- ^ 0.98 (GaO, 65 B0.35 * 2 X4: El \> .02

In automatic agate mortars, grind very finely for 1 h: - 2.5073 g Sr SO 3 - 4.0608 g Ga 2 O 3 - 0.8380 g Ba CO 3

- 0.4609 g MgO

- 0.1173 g Eu203 - 1.4427 g H3B03 6 65796 This mixture is applied in a thin layer of not more than 1 cm to a glassy carbon vessel (nacelle) at ambient temperature and placed in a tubular oven. Arrange the argon U flow.

The first heat treatment is then carried out according to the following program: - 3 h at 300 ° C in a stream of argon - 1/2 h - 3 h at 600 ° C in a stream of H 2 S - 2 h at a temperature of 820-850 ° in a stream of Cl 2 and the rise and fall of temperature occurs according to the slowness of the furnace (~ 500 ° C / h) and in the stream of argon U and the product leaves the cold furnace.

After re-grinding for 1 h in an automatic mortar, it is subjected to a second heat treatment under the above conditions according to the program: - 2 h at 820-900 ° C in H2S stream and temperature rises and falls according to furnace inertia in argon U stream and product leaves cold oven .

9 g of yellow compound (A 2) are obtained.

The compound is ground and then screened through a 40 sieve.

The arc spectrometer confirms the presence of boron and magnesium in the resulting compound.

Example 2 Comparative example

According to the technique described in Example 1, a compound of the prior art is prepared having the formula: (Βχ) (Sr0.80 Ba0.20) 0.98 Ga2 X4; Eu0.02 Using as starting materials 3.1591 g Sr CO 2 1.0557 g Ba CO 3 0.0961 g Eu 2 O 3 5.1164 g Ga 2 O 3 7 65796

10 g of compound B 2 are obtained, which is much weaker yellow than compound A 2.

Radiation by cathode excitation (15 kV, 1 μAA / cm2):

Figure 1 compares the radiation intensity for Compounds A 1 (invention), (prior art) and (a commercially available powder called Jedec P 2) It is found that the radiation of a compound of the invention is much stronger than that of both prior art compounds.

Figure 2 compares the radiation intensities of the same compounds A 1 and P 2 for different values of the excitation voltage of the excited electron jet (constant current density = 1 μAA / cm).

Figure 3 shows that at high excitation current densities, the response of the phosphor A 2 differs only slightly from the linear (15 kV).

Radiation with ultraviolet excitation (deuterium and xenon lamps)

Figure 4 clearly shows that the radiation of compound A 1 is stronger than that of compound B 1.

Figure 5 shows the excitation spectra at a radiation wavelength of 530 nm for compounds A 1 and B 2. The superiority of compound A ^ is clearly evident.

Example 3

Preparation of a compound of the invention having the formula: (A2) - "Ca0.65 Mg0.35} 0.98 (GaO, 65 BOf35 * 2-7 X4: Eu0.02

Work as in Example 1 (but carry out only the first heat treatment described) and use as starting materials: 1.453 g Ca CO 3 - 0.3153 g MgO -0.080 g Eu 2 O 3 - 2,779 g Ga 2 O 3 - and 0.987 g H 3 BO 3

5 g of yellow compound A2 are obtained.

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Example 4 Comparative example

Example 3 describes the prior art preparation of a prior art compound having the formula: (b2)

Ca0.98 Ga2 X4: Eu0.02 using as starting materials: - 1.8697 g Ca CC> 3 - 0.0671 g Eu203 - and 3.5733 g Ga2 O3

Compound B2 is obtained, which is less yellow than compound A2.

Radiation by cathode excitation (15 kV, 1 yUA / cm2)

Figure 6 shows that in the case of compound A2 there is a stronger radiation than in the case of compound B2 (according to the prior art).

Radiation U.V. with tuning (deuterium and xenon lamp)

Figure 7 further shows that the radiation is stronger in the case of compound A2 than in the case of compound B2.

Figure 8 shows the excitation spectra at 555 nm and confirms the superiority of compound A2.

Example 5

Preparation of a compound of the invention having the formula: -> Sr0.80 Ba0, 20 * 0.50 M90.50 - ^ 0.98 {Ga0.50 B0.50 * 2 X4: ^ 0.02

Work as in Example 1 and start from the following starting materials: 2.1305 g Sr CO 3 - 0.7120 g Ba CX> 3

- 0.7273 g MgO

- 0.1296 g Eu2 O3 - 3.4506 g Ga2 O3 - 2.2767 g H3 B03

Yellow compound A3 is obtained.

Claims (12)

1. Self-luminous substance, characterized in that it corresponds to the general formula MV 1-d 'a <Ga, -z Bz> 2-7 X1 * 3a! Eud (I> where M denotes at least one alkaline earth metal which is Ca, Sr or Ba y is greater than or equal to 0 and less than or equal to about 0.7 (0.0 <y <0.7) a is larger than or equal to about 0.8 and is different than 1, where y = 0 z is greater than or equal to 0 and less than or equal to y (0 <Z <y) X represents sulfur or a mixture of sulfur and oxygen , and d is a tai selected so as to obtain the desired luminescence where the luminescent substance is subjected to an instantaneous excitation energy. Self-luminous substance according to claim 1, characterized in that y is greater than or equal to about 0.10 and less than or equal to about 0.50 (0.10 <y <0.50) a = 1 z = y and d is between about 0.005 and about 0.20. Self-luminous substance according to any one of the preceding claims, characterized in that M is calcium. Self-luminous substance according to one of claims 1 and 2, characterized in that M is strontium.