DE1592910B1 - A method for producing an alkaline earth phosphate activated phosphor with monovalent copper and trivalent terbium - Google Patents

Description

The invention relates to a method for the technical superiority of the invention make a phosphor consisting of alkaline earth phosphate easily visible, den, with monovalent copper and trivalent ter- According to the invention it was found that a with

bium activated phosphor. Copper and terbium activated calcium halogen

The phosphors produced according to the invention 5 phosphate luminophore of the formula have suitable temperature characteristics for the

Use in fluorescent discharge lamps, especially 3 Ca ₃ (PO ₄ ) ₂ CaX ,: Cu, Tb,

especially in high pressure mercury lamps.

It is already known that the rare with ions I _n which X is a halogen or a mixture of earth metals, such as. B. terbium ions activated io halogens, when excited with ultraviolet phosphors excellent temperature properties rays of 2537 and 3650 A have a bright blue. The radiation intensity of this fluorescent substance shows green radiation, if the ratio is mostly low, since the absorptive copper atoms to calcium atoms are of the order of magnitude, the excitation energy of such ions is _rare from 0.01, · 1 and the ratio of the terbiumene earth metals fairly narrowly limited and weak 15 atoms to the calcium atoms is in the order of magnitude. of 0.003: Ibis 0.06: 1.

It is already known (see A. H. Mckeag: J. Elec- The peculiarity of the method according to the invention

trochem. Soc, 106, p. 1032 [1959]) that one with _r ens is that a phosphate and polyvalent copper activated calcium halide containing starting mixture of phosphate phosphor when excited with ultra-20 bonds of the alkaline earth metals, copper and Terviolet rays of 2537 A have a luminous bluebium, in which the ratio of the copper atoms to the white radiation with a maximum at 4800 A, the sum of the alkaline earth atoms between 0.002: 1 and. 0.02: 1, and the ratio of terbium atoms to

From the German patent specification 1132274, the sum of the alkaline earth atoms is between 0.003: 1 and Already a method for producing an alkaline earth 25 0.01: 1 is in a slightly reducing and orthophosphate phosphor known which copper is slightly humid atmosphere at a temperature and / or tin as an activator and at least one between 1100 and 1300 ° C is fired. As an earth element from the group of terbium, yttrium, gadoli alkali metals are preferably calcium or contains nium, lutetium and ytterbium. Calcium strontium compounds are used.

Compared to this known method, the 30 if a known halophosphate candlestick according to the invention is used If the following are beneficial to increasing amounts of terbium, the blue will be: white copper emission band gradually weaker

1. The firing temperature is gradually higher in the invention and the terbium emission. the 1100 to 1300 ° C with a burning time of about terbium emission is in this case in the main 2 Hours. This temperature is below the optimal 35 thing a line emission with a peak at len firing temperature of 1350 ° C according to the German 5450 A.

see patent specification 1132 274. The cost of the in F i g. 1 and 2 are the emission spectra of two

The system required for the process according to the invention are phosphors with low and high terbium concentrations therefore lower than with the known methods. tration shown.

2. The phosphor according to the invention consists of 40 The phosphor with a terbium-calcium-copper-activated calcium halophosphate and has an atomic ratio of 0.003: 1 to 0.06: 1 emits greater luminosity and chemical stability with blue-green luminescence. If, however, the higher temperature than the phosphor consisting of copper-activated ses ratio of terbium to calcium atoms strontium phosphate is increased to above 0.02: 1, the German copper-emission patent 1132 274 disappears. 45 Spectrum almost complete. The fluorescent material then shows the development of a fluorescent lamp becomes a fluorescent material with only one green emission. From the fact that, for example, as a suspension in a nitrocellulose high terbium concentration, the terbium radiation solution (as a binding agent) is applied to the tube wall - essentially the only radiation this with copper, which is then activated to decompose the binding agent and terbium calcium halophosphate 450 to 600 ° C is heated. "During this 50 phats, and from the fact that the excitation-burning the reaction Cu ¹⁺ - ^ Cu ^{2+ takes} place. Since the spectrum of the terbium radiation is almost the excitation-Cu ²⁺ no activating agent, the luminous spectrum decreases of the phosphor activated only with copper due to the formation of Cu ²⁺ , it can be seen that in the he-Da Qi ¹⁺ in the calcium-halogen phosphor produced according to the invention the terbium radiation is more stable than in the Stron-55 the copper emission centers is sensitized, tium orthophosphate phosphor according to the German The phosphor according to the invention shows a strah patent specification 1132 274, occurs with the terbium emission according to the invention, since the energy of the ultra-modern phosphor results in a lower formation of violet light by the copper emission centers Cu ^{2 +} when burning and thus less absorption and due to non-radiating energy transfer of the luminosity a. D The luminosity of the generation is transferred to the terbium, and thus the luminescent substance according to the invention is therefore 10% greater, so-called sensitized luminescence, than in the case of the luminescent substance according to the German Paragraph. On the other hand, with a rare Erdtentschrift 1132 274. In a fluorescent lamp of metal ions, such as. B. with terbium ions activated W, for example, when using the phosphor, no radiant emission can be achieved, phosphor according to German Patent 65 because its absorption capacity for excitation energy 1132 274 has a luminous flux of 65 LmAV, while for the reasons described above is very weak. The phosphor produced according to the invention has a current of 75 LmAV is achieved with the phosphor according to the invention. From this the excellent temperature properties are also based.

3 4

In the case of conventional phosphors, this can be achieved. The hydrogen content can be used in this

called thermal quenching at high tempera-mix between 1 and 20%, related

doors, and their luminance decreases to the total volume of the gas mixture; preferential

at high temperatures considerably. In this way one uses a mixing ratio between

However, phosphors according to the invention occur up to 5 2 and 5%. An amount of hydrogen less than

Temperatures of about 400 ° C not a substantial 1% is unacceptable as in such a case

Decrease in luminance. Therefore, all copper ions are suitable to remain in the divalent state,

this fluorescent material is particularly suitable for lamps whose one does not contribute to the desired emission, while

Walls are heated to high temperatures, such as rend an amount of hydrogen of more than 20%

it z. B. is the case with high pressure mercury lamps. io is also undesirable because in this case the

In the invention, a part of the calcium in the copper ion can be reduced to the metal.
Calcium halophosphate except for strontium

can also be replaced by barium. The emission. ^ ₁₁

Spectra, temperature dependence and other self-example 1

15 components of the raw mass amount (grams)

are not particularly different from those of the _o _, ... ,

Calcium halophosphate phosphor. The ratio- Secondary calcium phosphate .... 816

nis of the copper atoms to the atomic sum of this calcium carbonate 220

Alkaline earth atoms should be 0.002: 1 to 0.02: 1; £? ^{lclum α} ψ ^χα % ': ·. · · · · ■ · · ·. · % * _e

preferably one uses a ratio in which * « anhydrous calcium chloride .... 55.5

On the order of 0.01: 1. With a ratio ff ^ lilV A

of copper to the atomic sum of these alkaline earth atoms leroiumoxia (L D ₄ U ₇ ; $ ß

below 0.002: 1 the copper emission is too weak,

while at a ratio of over 0.02: 1, the above-mentioned constituents of the raw material copper emission as a result of concentration quenching are also completely pulverized and weakly decay together. The ratio of terbium atoms is mixing. Thereafter, the mixture is 2 hours at the sum of alkaline earth atoms is 0.003: 1 1230 ° C in a moist, 2% hydrogen from half to 0.06: 1. Burned at a ratio of terbium to the nitrogen flow. The phosphor produced in this way sum of the alkaline earth atoms of less than 0.003: 1 shows a luminous blue, the terbium emission cannot be achieved, 3 ° green emission when excited with an ultraviolet while with a ratio of more than 0.06: 1 radiation of 2537 A. as shown in Fig. 1, there is no further improvement in luminance.
can be achieved.

The phosphor produced according to the invention is Example 2

also gives when excited with ultraviolet light 35

of 3650A, under excitation with cathode rays Components of the raw mass Quantity (grams)

as well as under excitation with X-rays a “. .... ^. . _{,, A} Ο1λ.

bright blue or blue-green luminescence. By secondary calcium phosphate .... 8I6

Change in the ratio of activators copper calcium carbonate 200

and terbium can the luminescence color be changed 4 ° „, ^cmn ? ^uon _, γ ·. γ ■: j Jt

change. In this way the relative anhydrous calcium chloride .... 55.5

Intensities of the blue copper emission with a tw ^ ·? ΛπΓλ \ Jn λ

Maximum of 4800 A and the green terbium terbium oxide (Tb ₄ O ₇ ) 37.4

emission with a peak of 5450 A against each other

vote. 45 The above components of the raw mass are

The alkaline earths produced according to the invention are completely pulverized and mixed with one another.

Halophosphate phosphors are based on similar. Thereafter, the mixture is heated in for 2 hours at 1230 ° C

Like the calcium halogens used up to now - a nitrogen stream containing 3% hydrogen

Fired phosphate phosphors. burned. The luminescent light produced in this way

In particular, z. B. Calcium secondary 50 substance shows when excited with ultraviolet

phosphates, potassium carbonate, calcium chloride and rays of 2537 A produce a glowing green emission

Calcium fluoride completely in certain amounts (cf. FIG. 2).
pulverized and mixed. The mixture

a certain period of time at temperatures of _R. · 1 q

Fired 1100 to 1300 ° C. Firing temperatures be- 55 "s eispiei

see 1180 and 1230 ° C are preferred. For components of the raw mass, quantity (grams)

a firing temperature below 1100 ° C is the crystal ",, ..",. ,,. _ΟΛί1

Insufficient growth and results in a deficient secondary calcium phosphate .... 816

Luminance, while at a burning temperature caiciumcarDonai ζυυ

over 1300 ° C during sintering, an overly strong crystal ₆ ow ^ SeSs ^ ontiumchiorid \ \ \ 79

growth occurs. ν ta \ ά (Cn n \ ίο

The burning is in a slightly reducing τ ν ° ^? £ nV vr ±

and a slightly humid atmosphere, since " ^{L erDmmoxia} I ^{L 1} W ■> /, *

Copper as an activating agent in a monovalent

State must be introduced into the phosphor. 65 The components of the raw mixture listed above

Therefore z. B. with one made of hydrogen and are completely pulverized and mixed together

Nitrogen gas existing mixture that mixes a small one. Thereafter, the mixture is 2 hours at

Contains a lot of water vapor, a very good result 1230 ° C in a moist 5% hydrogen

burning nitrogen stream. The phosphor produced in this way gives a bright green color Emission when excited with ultraviolet rays of 2537 A. The emission spectrum of this The phosphor is almost the same as that in FIG. 2 spectrum shown.

Example 4

Components of the raw mass Quantity (grams)

Secondary calcium phosphate 816

Barium carbonate 394

Calcium fluoride 39

Calcium chloride anhydrous .... 55.5

Copper oxide (Cu ₂ O) 7.2

Terbium Oxide (Tb ₄ O ₇ )., 37.4

The ingredients of the raw mass listed above are completely pulverized and mixed with one another. Thereafter, the mixture is 2 hours at 1230 ° C in a moist 5% hydrogen containing Burned nitrogen stream. The phosphor produced in this way gives a bright green color Emission when excited with ultraviolet rays of 2537 A. The emission spectrum corresponds to almost the one shown in FIG. 2 spectrum shown.

Claims (2)

Patent claims: 1. A method for producing an alkaline earth phosphate, activated with monovalent copper and trivalent terbium phosphor, characterized in that a phosphate and halide containing starting mixture of compounds of alkaline earth metals, copper and terbium, in which the ratio of copper atoms to the sum of alkaline earth atoms between 0.002 : 1 and 0.02: 1 and the ratio of the terbium atoms to the sum of the alkaline earth atoms is between 0.003: 1 and 0.06: 1, is fired ^{in a slightly reducing and slightly humid atmosphere at a temperature between 1100 and 1300 ° C.} 2. The method according to claim 1, characterized in that as compounds of the alkaline earth metals Calcium or calcium strontium compounds are used. 1 sheet of drawings