DE3522909A1 - FLUORESCENT - Google Patents

Description

Fluorescent

This invention relates to a phosphor, and more particularly to one luminescent borate matrix

Fluorescent materials were used in fluorescent lamps until the late 1970s based on halophosphate used. Such phosphors emit they are excited in low-pressure mercury lamps by radiation of 253.7 nm, in a broad band of yellowish light. Dhtersuchurgen have shown that the light output through use a G-emix consisting of three phosphors, which emits blue (450 nm), green (540 nm) and red light (610 nm) Contains substances, can be improved. Such phosphors were made from rare earth metals, with the blue emission

2. + " ³ J +

on Eu -, the green emission on Tb - and the red emission on

-Ion emission based. Such fluorescent lamps containing a mixture of three or more phosphors and coated therewith have been available for a number of years.

Also known is a fluorescent tube with a fluorescent coating in the form of a G-emic halophosphate phosphor activated by divalent europium as a blue light emitting luminescent Substance or halophosphoborate phosphor activated with divalent europium, coactivated by cerium and terbium Green light emitting phosphor containing silicon phosphate and yttrium oxide phosphor activated by trivalent europium containing red light emitting phosphor. Another already known one used in fluorescent tubes Phosphor layer contains Ba-Mg-aluminate activated with divalent europium as a blue light-emitting luminescent one Fluorescent material, Ce-Hg-aluminate activated with terbium as green Light-emitting phosphor and yttrium oxide activated with trivalent europium as a red light-emitting phosphor. The use of such phosphor layers containing a plurality of phosphors as mixtures, however, has certain serious disadvantages tied together. The homogeneous mixing of powders with different physical properties and the production of a

3522309

homogeneous rails on the lamp bulb have proven to be exceptional proved difficult. The individual luminescent substances in the lamp have different durability, i.e. the color of the light supplied by the lamp changes with the burning time if one of the phosphors loses its light intensity « In addition, the quantum yield with such a mixture of several phosphors is never as good as with the individual phosphor. The excitation energy cannot be used to the maximum because part of it is lost due to shading, grain boundaries, and the like.

The present invention thus aims to achieve the aforementioned To eliminate deficiencies and to create a luminescent material, in which one and the same luminescent material with the same Suggestion times can get two or more colors. Selective excitation methods with different energies are used by some Substances receive different colored emissions earlier; In sensitizer-activator systems, the self-emission wavelength some sensitizers fall in the visible range, however the intensity of the emission of the sensitizer was then generally weak. In principle, different types of absorbing and emitting ions in the phosphors interfere with one another. in the generally there are no concentrations of impurities in such phosphors permissible, which is the order of magnitude of some. 10 ppm exceed.

The present invention is therefore also intended to provide a phosphor be created, in which the mutual animal effect and disturbance of the luminescent ions is as low as possible, and in which the possibility of producing several emission colors is given

t.

The main principles of the invention are set out in the appended Claims.

The invention thus relates to a luminescent borate matrix which has the general formula La, Γ, Eu ^ ⁺ (Mg, Zn) Bc-O-, _Q , and which is structured so that both the La / Y ions, Eu and the Mg / Zn ions are arranged in one-dimensional rows. Mg ⁺ and

⁺ can completely replace each other in the lattice without changing the structure of the "connection. In den.La rows

COPY

-S-

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the distance between the La ions in the row is significantly smaller than the distance between the La ions from row to row. The ions, which form two-dimensional (B ₁ -O ₁₀ ⁵ ") networks, are arranged between the rows of cations. The La ions are coordinated in 10 oxygen atoms, which form an irregular coordination polyhedron. The Mg / Zn ions, in turn, are located in the Middle of an elongated octahedron formed by 6 oxygen atoms In the luminescent matrix ^{according to the invention, M 3+} activators can be substituted for the La ion and VT ⁺ activators can be substituted for the Mg / Zn ion that with such a luminescent matrix no hereditary concentration extinction occurs, which means that the activator concentrations are not critical but can vary within wide limits.

According to the present invention, the La ions may or may not be partly by trivalent Tb- and possibly by Gd-, Oe- and / or B1 ions are replaced. In the Hg / Zn series, MR / Zn be partially substituted by divalent JIn or Eu ions.

The excitation and emission wavelengths of the following luminescent ions in the La (I-Ig, Zn) BcO _1Q matrix are:

The ions with a broad absorption or .Smissionsband can depending luminesce with slightly different wavelengths after activator concentration.

The table shows that, due to the spectra, energy transfers from bismuth and cerium to the 4f from terbium and europium are possible. Experimentally it was further proven that the transmissions Ce'i-e> Gd ' ⁺ and Bi ⁵ ^ - * »Gd are also possible. The special property of gadolinium, ie the fact that the lines at 313 nm can also absorb, makes this possible. Energy can also go from gadolinium to europium

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Λ /
Suggestion ' ■ emission 270 300 290 330 277 313 250 (CTS), 290-410 C4f) 610 (maximum) 200 (4f-5d), 290-390 (4f) 542- '" 280-330 630 330 430

Ip

-4- ■

and skip terbium. The energy can very much in the gadolinium lattice cover long distances and even skip from one La row to the other.

The above only applies to the energy transfer in the series formed by the trivalent cation. An energy transition from the La ^ ⁺ series Ο. Oi

the Mg / Zn series can also be achieved with both bismuth and gadolinium. Cerium, on the other hand, transmits poorly Energy on the two-valued series.

If excitation energy is entered into the gadolinium-containing lattice, the energy is transferred quickly through the entire Gd series. At the end of the series, the energy can hit a non-luminescent ion, lanthanum, and the energy then returns or skips over to the following gadolinium series can. If the excitation energy has migrated long enough and only encountered La ions at the end of the gadolinium chains, a discharge finally occurs, generating the emission characteristic of gadolinium. When passing through numerous grid points, the energy can of course also hit a grid defect, which then leads to a radiation-free discharge. If, on the other hand, the energy introduced into the gadolinium series meets a luminescent ion (Eu ^ ⁺ , Tb) at the end of the series, it excites the ion, which cannot pass the energy on but emits it as light (red, green). In the gadolinium lattice, as already mentioned, the energy can also ^{pass to an Mg +} series and there to a Iu-

Ol Ol

meet minescent ion (Mn, Eu), which is excited and will be emits characteristic light (red, blue). -

The phosphor according to the invention contains relatively long rows of gadolinium, which are interrupted either by lanthanum or a small amount of europium and terbium. As a result of the structure of the La (I-Ig, Zn) B ₁ -O _{1 n} lattice and the low activator concentrations, Eu / and Tb ^ are able to luminesce on their own, and the mutual extinction observed in other materials does not occur. It is also possible to incorporate both divalent Eurouium and trivalent Europium into the La (IIg, Zn) B ^ O _lo matrix and to obtain visible luminescence from both. This is the only one known

Substance in which the blue emission of Su and the red emission 'Z.

from Eu- ^ are clearly visible. With the phosphor according to the invention, there is the possibility, by choosing activator combinations, green and red emission ( ¹ Tb ⁵⁺ , Eu ⁵⁺ and / or Tb ⁵⁺ , Mn ²⁺ ), blue and red emission (Eu ⁺ , Eu ^ ⁺ ), highly intense red Emission (Eu ⁺ , Mn ⁺ ) or even blue, green and red emission (Eu ⁺ , Tb, Eu and / or Mn.). Different color tones can be created by changing the activator concentrations.

When using fluorescent material according to the invention in low-pressure mercury lamps Instead of 3 to 4 phosphors, only 1 to 2 phosphors are required. The manufacture of the lamp is thereby relieved, and the quantum yield improves. With a

• x. ρ +
Eu ^ - and Mn -activated compounds, a strong red emission can be generated in which the band and line spectrum are superimposed. The material is ideal for "de luxe" lamps where good color rendering is desired.

In the following, the invention will be described in detail by means of examples and with reference to the accompanying drawings. In the drawings, FIG. 1 shows the grouping of the various ions in the plane ac of the matrix La (Mg, Zn) B ₅ O-, _Q , FIG. 2 in the plane ab without showing the oxygen atoms, and FIG. 3 in the plane bc without representation of the oxygen and boron atoms. Figures 4 to 7 show emission spectra of phosphors according to the examples below.

The production of the phosphors according to the invention belongs to the Area of expertise of the person skilled in the art and is carried out in such a way that the required ions as compounds, for example as oxides, mixed with one another and then selectively heated in a reductive atmosphere. Making some special advantageous phosphors are described in the following examples.

At SOJel 1

A mixture of 4.078 3 Gd ₂ O ,,

O, 4? L -τ ^ b ₄ O ₇

Ο, ΐϊο g -Ui-igO-

1.058 grams of MgO

9.656 g H ₅ BO ₅

■ - * - 3522903

was dissolved in 40 cm concentrated nitric acid. The solution was evaporated and the residue was ground to a homogeneous mixture. ^{This mixture was first heated to 400 °} C. in a reducing gas atmosphere, the water and nitrogen oxides being lost; The mixture was then held for one hour at 700 ⁰ C and then three hours 95O ⁰ C. The material was cooled, homogenized and then subjected again to a reducing treatment ^{at 95O 0 C.} After cooling, the material is ground and the excess boric acid can be washed out with water. The emission spectrum of the product (Gd ₀ nTb _{0 og} Eu _o Q ₁ ) MgB ₅ O ₁₀ is in Pig. 4 shown. In the excitation spectrum, both the Eu band and the sharp tip of Gd ^ ⁺ and the sharp 4f tips of Eu- ^ ⁺ and Tb ^ ^{+ are} visible.

During production, an excess of boric acid should be used, as some boron oxide evaporates when heated. The course of the reaction is also promoted by the excess boron. The reaction product can also be ground after each individual heating stage (400 ^° C. and 700 ^° C.).

Example 2

The mixture according to Example 1 is homogenized in the Kugelmithle and heated as in Example 1 in a reductive gas atmosphere. Since there is no dissolution, additional grinding and heat treatment at 95O ⁰ C are necessary.

Example 3

A mixture of 6.682 g of La ₂ O-

3.066 g Eu ₂ O ^. ■ ■ *

1.704 g of MgO
19.228 g H ₃ BO ₅

is treated as in the above examples in a reductive gas atmosphere, the product (La _Q Q ₂₅ Eu _{0 175} ) (Mg ₀ 325 ^Eu o 175 ^ ^B 5 ° LO being obtained.

The absorption spectrum of this material is composed of two bands: the CTS band of trivalent europium at 250 nm and the 4f-5d band of divalent europium at 350 nm. The excitation spectrum of the blue emission of Έη ~ ⁺ also includes

250 nm a band, v / as Bu ^ -Eu 'energy transition means. The emission spectrum the material is in Pig. 5 shown.

Example 4

A mixture of 0.021 g Ce (SO.) ₂ »4H ₂ O

0.224 g of La ₂ O ₃

0.187 g Gd ₂ O ₃

0.010 g of Tb ₄ O ₇

0.023 g Eu ₂ O ₅

0.106 g of MgO

0.994 g H ₅ BO ₃

is treated as in the above examples in a reducing gas atmosphere. The resulting product corresponds to the formula (la ,.

The emission spectrum of the product contains the colors of all three emitting ions (Eigur 7).

At SOJel 5.

A mixture of 3.571 g of La ₂ O-

0.475 S Ga ₂ O ₃

0.235 g Bi ₂ (CO ₃ ) ₃

0.133 g Eu ₂ O ₃

0.150 g HnCO ₃

1.049 g MgO 10.036 g H ₃ EO ₅

is treated as in the above examples, but the gas atmosphere does not need to be reductive. A product is obtained ( ^la O, 4S ^Gd O, 10 ^Bi 9, O3 ^Eu O, O3 ^{) (r} - ^g O, 95 ^IIn O, O5 ⁾ 35 ° 10 ' ^{which has a very} intense red emission because it is contains two activators emitting in the red area (Pi ^ ur 6).

Example 6

A lemic of 1.402 g Y2 ° 3

2.252 s Gd ₂ O ₅

1.153 g CeClC-7H ₂ O

0.546 g Eu ₂ O ₅

O, 6 ^! 58 * "MO

BADORIGfNAL ± j, 0U4 _; -: i, _v ; o ^

is treated analogously to the above examples in a reducing gas atmosphere. The resulting product corresponds to dot

Formula (* _Of 4 ^Gd O, 4 ⁰⁶ O ₁ I ^ O, 1> (^ 0.5 ^ 0.5 ^{) Β} 5 ° 1Ο '

Terbium acts as an activator in the product, giving the product its typical green emission. Cerium acts as an absorbent for UV radiation, and the gadolinium transmits the energy to the terbium. In the visible range only the spectrum of Eu ^ ^{+ can be} perceived.

-JU

summary

This invention relates to a luminescent borate matrix of the general formula La, Y, Eu (Mg, Zn) BcO-, _Q , ivor in which the lanthanum can be partially or completely replaced by yttrium., And in which the Eu-, La / Y- form and Jmg / Zn ions dimensional rows "and the two-dimensional between these located borate ions ^T Jetze form, in which the La / Y ions and the Eu ^ ⁺ ions are coordinated in 10 oxygen atoms, while the Hg / Zn ions are located in an octahedron formed from 6 oxygen atoms, this matrix being activated by J> r ⁺ activators located at the location of Ia / Y ions and by It activators located at the location of Tfg / Zn ions, where W of Tb and possibly from Gd ⁵⁺ , Ce ³⁺ and / or Bi ⁵⁺ and M ²⁺ from Mn ²⁺ or Eu ²⁺ .

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Claims (7)

Claims QJ. Luminescent borate matrix, characterized in that it has the general formula La, Y, Eu " ³ " ¹ "(Mg, Zn) B ₀ -O-, ₀ , in which the lanthanum can be partially or completely replaced by yttrium, and in which the La / Y ions, the Eu ^ ⁺ and the Mg / Zn ions form one-dimensional series and the borate ions between these form two-dimensional networks in which the La / Y ions and the Su ions are coordinated in 10 oxygen atoms, while the Mg / Zn ions are located in an octahedron formed from 6 oxygen atoms, this matrix being activated by W " activators at the site of Mg / Zn ions and possibly by M at the site of La / Y ions Activators, where M is formed from Tb and possibly from Gd, Ce and / or Bi ^ and IC "from Mn or from Eu. 2. Luminescent borate matrix according to claim 1, characterized marked that they have the general formula wherein: 0 <u <0.99 0 <v <l-u-x-y-z 0 <x <O, 3
0.005 <y * 0.7
0.005 < ζ <: 0.7
u + x + y + z <l 3. Luminescent · borate matrix according to claim 1, characterized in that marked that they have the general formula 0 ± Y ^ l - η - χ - ζ 0 ^ x <0.3
0.005 ^ z ^ 0.7
u + χ + ζ ± 1
0.005 i? Over 0.7 4. Luminescent borate matrix according to claim 1, characterized marked that they have the general formula O <u < 0.99 Of? <L-u-x-y-z 0 <χ <0.3 0.005 <y < 0.7 0.005 < ζ < 0.7 u + x + y + z = l 0.005 <r <0.7 5. Luminescent borate matrix according to claim 1, dadurc marked that they are the general pormal ' ^WOrin: O <u <0.99 O <ν <_ 0.3 Ofxfl-uv- ζ 0.005 <ζ <0.7 u + χ + ζ £ 1
0.01 <ρ <0.3 6. A luminescent borate matrix according to claim 1, characterized in that they have the general Pormel .u- ^ ^ xy _Z ^a V ^e r ^ ^Jb y ^ 2 _i ^{(^ Zn)} lpr ^ ^Bu t ^B 5 ⁰ 10 ^{has' wherein :} O <u <0.99 0 <v <luxyz O <χ < 0.3 0.005 <y <0.7 0.005 <ζ <0.7 u + x + y + z <l 0.01 <ρ <0.3 0.005 <r ^ 0.5 7. Luminescent borate matrix according to any of the above claims, characterized in that the La partially or is completely replaced by Y.