DE1592910C - Process for the production of an alkaline earth phosphate activated phosphor with monovalent copper and trivalent terbium - Google Patents

Description

1 2.

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 ₂ : Cu, Tb,
especially in high pressure mercury lamps.

It is already known that those with ions rarely i _n which X is a halogen or a mixture of earth metals, such as. B. terbium ions activated 10 halogens, when excited with ultraviolet phosphors excellent temperature properties rays of 2537 and 3650 A have a bright blue. The radiation intensity of this luminescent substance shows green radiation, if the ratio is mostly low, since the absorptive copper atoms to calcium atoms in the order of magnitude limit the excitation energy of such ions from 0.01: 1 and the ratio of the terbium earth metals rather narrowly and weak i ₅ atoms to the calcium atoms is of the order of magnitude. from 0.003: 1 to 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 a with rens is therefore that a phosphate and

polyvalent copper activated calcium halide containing starting mixture of

phosphate phosphor when excited with ultra-ao bonds of the alkaline earth metals, copper and ter-

violet rays of 2537 A a luminous bluebium, in which the ratio of the copper atoms to

white radiation with a maximum at 4800 A sum of alkaline earth atoms between 0.002: 1 and

having. 0.02: 1, and the ratio of terbium atoms to

From German patent specification 1 132 274, the sum of the alkaline earth atoms is between 0.003: 1 and

Already a method for producing an alkaline earth 35 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 earth

Element from the group 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 luminous

inventive method the following advantages substance increasing amounts of terbium, the blue-

on: white copper emission band gradually weaker

1. The firing temperature is gradually higher in the invention and the terbium emission. the HOO 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 1,132,274. The cost of the in Figs. 1 and 2 are the emission spectra of two

the system required for the process according to the invention phosphors at low and high terbium concentrations

are 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. However, if the higher temperature than the phosphor consisting of the copper-activated ses ratio of terbium to calcium atoms strontium phosphate is increased by over 0.02: 1, the German copper-emission patent specification 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 occurs, the reaction Cu ¹⁺ - ^ - Cu ^{2+ takes} place. Since the spectrum of the terbium radiation is almost ^{no activating agent for the Erre-Cu 2+} , the luminous spectrum of the power of the phosphor activated only with copper decreases due to the formation of Cu ²⁺ . It can be seen that in the er-Da Cu ¹⁺ in the inventive phosphor according to the invention, the terbium radiation is sensitized to cium halogen phosphor more stable than in the stron 55 by the copper emission centers, tium orthophosphate phosphor according to the German The phosphor according to the invention shows a strah patent specification 1132 274, occurs with the invention! ende terbium emission, since the energy of the ultra-modern fluorescent material a lower formation of violet light by the copper emission centers Cu ²⁺ during burning and thus a lower absorption and by non-radiating energy transfer Luminosity on. The luminosity of the generation is transferred to the terbium, and thus the luminophore according to the invention, is therefore 10% greater, a so-called sensitized luminescence, than with the luminophore 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. 400 W activated with terbium ions, 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 Lm / W, while for the reasons described above is very weak . with the phosphor according to the invention a light The phosphor produced according to the invention has a current of 75 Lm / W is achieved. From this the excellent temperature properties are also based.

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 l ° / o 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,

spectra, temperature dependence and other intrinsic Example 1

these halophosphate luminescent substances under 15 constituents of the raw mass' amount (grams)

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

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; · ™ ^at "V ⁰⁰ Jv ₁ " ·. ·· · ■ ·. · ■■ '* 9

a ratio in dei * ° anhydrous calcium chloride .... 55.5 is preferably used

Order of magnitude of 0.01: 1. With a ratio of K.upter (l) -oad (tUjU) 7.-

of copper to the atomic sum of these alkaline earth atoms lerbiumoxicn ID ₁ U ₇ J ir »

below 0.002: 1 the copper emission is too weak,

while at a ratio above 0.02: 1 the. The above-mentioned constituents of the raw material copper emission as a result of concentration extinction are also completely pulverized and weakly decay with one another. 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, 30 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 ", ... _,. . ,,.,.,

bright blue or blue-green luminescence. By secondary calcium phosphate ... 816

Change in the ratio of activators copper calcium carbonate 200

and terbium one can change the luminescent color 40 caiciumnuona SJ

to change. In this way, the relative water re.es Cakiumchlorid .... 55.5

Intensities of the blue copper emission with a £ "u · · 5 λγκ ΪΙ \ ή 1

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

decide by 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

In the same way as 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

phosphate, 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

is a certain period of time at temperatures of _R. . . ,

Fired 1100 to 1300 ° C. Firing temperatures between 55 Example s

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

a firing temperature below 1100 ° C is the crystal _c , ... _n , -. _m . """,,". _{Q1 /} -

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

Luminance, while at a firing temperature calcium carbonate , ZW

over 1300 ° C during sintering, an excessively strong crystal- 60 ^ At ^ ti ^ hiorid "! '.'. 79

growth occurs. KuDferil Voxid fCu CO 7 2

The burning is in a slightly reducing τν, - L-sa cru A \ ιί'α

and slightly humid atmosphere, since lerbiumoxia (ι D ₄ U ₇ J si ^

Copper as an activating agent in a monovalent

State must be introduced into the phosphor. 65 The components of the raw mass listed above B. with a mixture consisting of hydrogen and are completely pulverized and mixed together with nitrogen gas, which mixes a small one. After that, the mixture will contain a lot of water vapor for 2 hours, a very good result of 1230 ° C in a moist 5 ⁰ Zo hydrogen.

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

Example 4

Components of the raw mass Amount (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.) 37.4

The ingredients of the raw mass listed above are completely pulverized and mixed with one another. Thereafter ¹ the mixture is burned for 2 hours at 123O ⁰ C in a moist nitrogen stream containing 5% hydrogen. The phosphor produced in this way gives a luminous green emission when excited by ultraviolet rays of 2537 A. The emission spectrum is almost the same as that in FIG. 2 spectrum shown.

Claims (2)

Patent claims: 1. A process for producing an alkaline earth metal halophosphate with monovalent Copper and trivalent terbium activated phosphor, characterized in that a starting mixture of compounds containing phosphate and halide Alkaline earth metals, copper and terbium, in which the ratio · of the copper atoms to the sum of the Alkaline earth atoms between 0.002: 1 and 0.02: 1 and the ratio of terbium atoms to The sum of the alkaline earth atoms is between 0.003: 1 and 0.06: 1, in a slightly reducing and slightly humid atmosphere at a temperature between 1100 and 1300 ° C will. 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