DE2917931A1 - LOW PRESSURE MERCURY VAPOR DISCHARGE LAMP - Google Patents

Description

N.V. Philips' Bloeiiampenfabrbkcn, Eindhoven 291793t

12/20/78. Ji PHN 9115

Low pressure mercury vapor discharge lamp.

The invention relates to a low-pressure mercury cap discharge lamp with a luminescent layer resting on a carrier, the · a luminous active with europium and manganese or with cerium and manganese

B contains fourth aluminate with a hexagonal magnetoplumbite structure.

Some aluminates with a hexagonal magnetoplumbite structure are known which have a large trivalent Cation (especially lanthanum and / or cerium) contain.

_{The compositions Ln 2} O ".nAl" O and Ln "0" .2MgO.mAl ₂ O "are often given for these aluminates, in which Ln represents lanthanum and / or cerium and where η generally has a value of 6 to 9 and which is given a value from 5 to 7 for m. It has been found that the active crystalline phase of these substances with the formula "Q / -O" ,,. Al .. ".Ο., For the magnesium-free aluminates O ₁ OO O, 14 11.90 19

and with the formula Ln _Q Q ₂ ⁰ O 08 ¹¹⁶ ^ ¹ II 13 ° 19 ^{for the} nesium-containing aluminates is represented well approximated. X-ray diffraction measurements have shown that some of the Ln sites in these crystal lattices are occupied by oxygen ions.

The activation of these aluminates with various activator elements can result in very effective phosphors to lead. From GB-PS 1> 52 083 there is a large number luminous manganese-containing aluminates known. In this

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Patent specification describes, inter alia, lanthanum magnesium aluminates activated with Eu and Mn and activated with Ce and Mn. / The Eu, which completely or preferably partially replaces the La in the lattice, and the Ce, the La preferably completely replaced, serve as a sensitizer for the manganese emission. The known Aluminates have strong green manganese emissions (emission maximum at around 515 nm; half-width the emission band 25 to 30 nm).

W In the publication in "Jap. J. Appl. Phys. '

13> (197 ^) 95O describes the green manganese luminescence of the (magnesium-free) lanthanum aluminate activated with Eu and Mn. A very effective green manganese emission ■ can be obtained with Ce and Mn activated (magnesium-free) aluninates of lanthanum and barium (see Dutch patent application 75 Ok 502).

The invention is based on the object

To create phosphors with an emission in the deep red region of the spectrum. Such substances can, for example, can be used advantageously in discharge lamps, for example "in low-pressure mercury vapor discharge lamps, to promote plant growth. It is well known that photosynthesis is most effective in green plants promoted by radiation with a wavelength in the range of 650 - 700 nm.

The low-pressure mercury according to the invention vapor discharge lamp is provided with a layer of fluorescent material placed on a carrier, which creates a luminous, aluminate activated with europium and manganese or with cerium and manganese with a hexagonal magnetoplumbite structure contains, and is characterized in that the aluminate corresponds to one of the following formulas:

^a) [ ^La O.92 (ix) ^EU x ° O, O8 (ix) J ^M Si- _y ^Mn y ^Al 11.13 ₊ O, 2x ^O 19

^b) f ^La 0.86 (ix) ^Eu x ° 0, i4 (ix)] ¹¹ V ¹ I 1 _i9 0 ₊ 0, Ix-O, 67y ° 19

°) f ^La 0.92 (ip) ^Ce 0.92p ° 0.08] " ^M ^ 1-y ^Mn y ^Al 11.13 ° 19

^d) [ ^La 0.86 (ip) ^Ce 0.26p ° 0.14j ^Mn y ^Al ii, 90-0.67y ° 19

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e) linear combinations of a) and b)

f) linear combinations of c) and d), where 0.01 ^ x ^ 0.30

It was found that the hexagonal aluminates, which have a large trivalent cation (La and / or Ce) when activated with Eu and Mn or with Ce and Mn in addition to the green emission of divalent manganese may also have a red emission band of bivalent manganese. This red manganese band has a maximum at about 690 nm and a half width of about 115 nm. In some cases is next to the red and green Mn emission also radiation from the sensitizer (Ce or Eu) perceptible. Attempts to Invention have shown that the red manganese emission only occurs at a relatively high manganese content occurs. It is assumed that in these AIuminates the excitation energy from the sensitizer to green Mn centers and from there to red ones

* Mn centers are transmitted only at sufficiently high levels Mn concentration exist. In the aluminates according to the invention therefore the Mn content (y in the above formulas) must be at least 0.5, because 50 ^ of the sent Radiant energy or above received in the red Mn band can be. The manganese content y is chosen not to exceed 0.9, because values above 0.9 reduce the light yield Concentration extinction drops. If Eu is used as a sensitizer, the Eu content is chosen between 0.01 and 0.30. With values of χ below 0.01, the absorption of the stimulating radiation is too low and with values from χ over 0.30 losses are determined in the europium itself. If Ce is used as the sensitizer, the Ce concentration ρ between 0.1 and 1.0 is chosen. It appears, that in this case the lanthanum can be completely replaced by the sensitizer.

It should be noted that in the aluminates according to the invention a part (for example up to 50 mol ⁰ Jo) des

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ORIGINAL INSPECTED

12/20/78 ' K PHST 9115

Lanthanum or Lanthanum and Ce by. strontium and / or barium can be replaced because the related alkaline earth aluminates with hexagonal crystal structure at least are partially soluble in the lattices of the aluminates according to the invention. Such a substitution offers however, no advantages in terms of the luminous efficiency and the emission color and will therefore be used in practice not applied. ..., .-., -..-.---

A preferred group of the JO lamps according to the invention contains an aluminate which has the formula a) or c) corresponds to, where 0.10 ^ x ^ 0.25, 0.8_ ^ p <1 1.0 and 0.6 ^ Ty • ^ O.7 · With these values of x, y and ρ become in particular in the case of the Mg-containing aluminates, optimally luminous substances are obtained, in particular at least 8θ? Έ of the emitted radiation energy in the red Mn band is found and very high luminous flux levels are achieved.

Another preferred group of the lamps according to the invention contains an Mg-free aluminate of the formula b) or d), where 0.10 <χ <0.25, 0.8 ^ ρ <1.0 and 0.7 ^ y ^ C Ό > 8 is. It has been shown that optimal results are achieved for the Mg-free aluminates with slightly higher Mn contents (y between 0.7 and 0.8), with 80% of the emitted radiation energy "or more in the red Mn band lies.

An embodiment of the low-pressure mercury vapor discharge lamp according to the invention is preferred in which the phosphor layer also contains a blue-luminescent substance with an emission maximum between 420 and 470 nm. Such a lamp offers great advantages in particular when used for irradiating plants. It has been shown that the presence of a small amount of blue radiation compared to red radiation is necessary for a good development of the plant shape (photomorphogenesis). _{An aluminate of the formula Ba Eu MgAl O 17} , in which 0.01 ^ q ^ "is 0.50, can advantageously be used for this blue luminous substance. These luminous substances are very effective

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* 231793t

Aluminates are known from the aforementioned GB-PS Ik 52 O83, to which reference is made for further details.

Embodiments of the invention are explained in more detail below with reference to the drawing. It demonstrate:

Pig. 1 schematically shows an inventive Low pressure mercury vapor discharge lamp and

Fig. 2 in a graphical representation of the spectral energy distribution of such Lamp emitted radiation.

In Fig. 1, 1 is the glass bulb of a low-pressure mercury vapor discharge lamp. The electrodes 2 and 3 between which the discharge is maintained are arranged at the ends of the lamp. The bulb 1 also serves as a carrier for the phosphor layer h, which lies on the inside of the bulb 1. The layer k contains a luminous aluminate according to the invention and can be applied in one of the ways known per se. The luminous aluminates according to the invention can be obtained by a solid reaction at high temperatures (for example 1200-1500 ° C.) in a mixture of oxides of the compound-forming elements or of compounds which can give these oxides at higher temperatures. In general, it is advantageous to carry out the heating of the starting mixture in two or more steps, wherein after each heating the product obtained is comminuted after cooling. At least the final heating step is carried out in a mildly reducing atmosphere (e.g., 1 to 2 "vol. Hydrogen nitrogen) to convert the manganese into the desired divalent state.

In the table below are the formulas of a number of working examples according to the invention Aluminates indicated. When used in lamps, it was determined what part of the manganese emitted Radiant energy was in the red Mn band. In the table

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The results of these measurements are given under "° ß> Red". In addition to the Mn emission, most substances also have a "'small contribution in the blue region of the spectrum from the divalent europium. Examples 1 and

2 relate to substances containing Mg of the general formula a). Examples 5 to 9 relate to Mg-free Substances of the general formula b). The examples

3 and 4 are aluminates from linear combinations of formulas a) and b) in the ratio 60:40 and 30: The aluminate of Example 2 shows predominantly when excited by ultraviolet radiation of one wavelength of 254 nm has a quantum yield of approximately 55% and the aluminate of Example 9 of approximately

TABEL

at
game formula ° / o red
Φ 1 ,
2
3
4th
5
6th
7th
8th
9 ^La O, 73 ^Eli o, 2i%, o6 ^M ^ o, 5O ^Mll O, 5O ^Al 11, i7 ^O i9
^La O, 73 ^Eu O, 21%, o6 ^M e _O , 33 ^Mn O, 67 ^Al 11.17 ^O 19
^La O.71 ^EU O.21%, O8 ^M & O.2O ^{Mn O.67 Al} 11.29 ° 19
^La O, 695 ^Eu O, 2i%, 095 ^Mg O, i47 ^Mn O, 51 ^Al 11 ^ 57 ^O 19
^La O.85 ^Eu O, O1%, 14 ^{Mn O.65 Al} 11.47 ° 19
^La O.85 ^Eu O, O1%, 14 ^{Mn O.75 Al 11.4o O} 19
^La O.68 ^{Eu O.21} %, 11 ^{Mn O.58 Al} 11.53 ° 19 "
^La O, ^Eu O 68, 21%, 11 ^Mn O, 63 ° 19 ^Al 11,5O
^La O.68 ^{Eu O.21} %, 11 ^{Mn O.72 Al} 11.44 ° 19 55
96
9h
52
73
97
57
78
97

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Fig. 2 shows the spectral energy distribution

of an aluminate of the formula ^ ₀ , 68 ^ ₀ , Zi ° 0, M ^Mtl 0.90 ^Α1 1Λ, 32 0 _1Q when excited by short-wave ultraviolet radiation (predominantly 2 ^ k nm). In this figure, the wavelength in nm is plotted on the horizontal axis and the radiation intensity I is plotted in any units on the vertical axis. It shows that this substance has almost no green Mn emission (at around 515 nm) and that almost all radiation originating from manganese is found in the red band with the maximum at 69Ο nm. However, the blue Eu emission band (maximum at "approx. 450 nm) is perceptible.

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Claims (1)

2O.12.78 # PHN 9115 Claims t 1 . Low-pressure mercury vapor discharge lamp with a phosphor layer resting on a carrier, which is a luminous aluminate activated with Eu and Mn or with Ce and Mn with a hexagonal magnetoplumbite structure contains, characterized in that the aluminate corresponds to one of the following formulas: b) ^ Ο, 86 (ΐ-χ) ^Ευ χ ° Ο, ΐ4 (ΐ-χ)] ^} [ ^La O, 92 (ip) ^Ce O, 92p ° O, O8j ^d) [ ^La O, 86 (ip) ^Ce O , 86p ° O, 1i e) linear combinations of a) and b) f) linear combinations of c) and d), where 0.01 ^ x ^ 0.30 0.1 ^ p ^ 1, 0 0.5 <C y ^ 0.9. 2. Low pressure mercury vapor discharge lamp according to claim 1, characterized in that the aluminate corresponds to formula a) or c), wherein 0.10 ^ x <C 0.25 0.8 <C p ^ 1, 0 o, 6 ^ y <1 ö> 7 · 3. ■ low-pressure mercury vapor discharge lamp after 909846/0723 12/20/78 '2 PHN 9115 Claim 1, characterized in that the alumina t corresponds to the formula b) or d), where. . ■ P, 10 ^ x ^ 0.25 0.8 ^ p ^ .1, 0 k. Low-pressure mercury vapor discharge lamp according to Claim 1, 2 or 3 »characterized in that the phosphor layer also contains a blue-luminescent substance with an emission maximum between 420 and 470 nm. 5. Low-pressure mercury vapor discharge lamp according to claim h, characterized in that the blue luminescent substance is an aluminate of the formula B Ba Eu MgAl ₁₀ O ₁ -, where 0.01 <C q <C, 0.50. / o / Luminous things with Eu and Mn or with Ce and Mn Activated aluminate having a hexagonal magnetoplumbite structure for use in a lamp according to claim up to 5j characterized in that the aluminate corresponds to one of the following formulas: ^a ) E ^La O.92 (ix) ^Eu _X ° O, O8 (ix)] ^M ^ 1 ~ y ^Mn y ^Al 11.13 + O, 2x ° 19 ^b) [ ^La O.86 (ix) ^Eu x ° o, i4 (ix)] ^Mn y ^A1 ii, 90 ₊ 0, i _x -o, 67y ⁰ i9 • °) t ^La 0.92 (ip) ^Ce 0 , 92p ° 0.08 J ^Mg 1-y ^Mn y ^Al 11.13 ° 19 ^d ) [ ^La o, 86 (ip) ^Ce o, 86 _P ° o, 14] ^Mn y ^Al 11,9O-O, 67y ° 19 e) linear combinations of a) and b) f) linear combinations of c) and d), where 0.01 ^. χ ^ 0.30 0, 1 - ^ p <^ 1, 0 909846/0723