US3575879A - Bivalent europium activated barium octaborate luminescent material - Google Patents

Bivalent europium activated barium octaborate luminescent material Download PDF

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Publication number
US3575879A
US3575879A US823347A US3575879DA US3575879A US 3575879 A US3575879 A US 3575879A US 823347 A US823347 A US 823347A US 3575879D A US3575879D A US 3575879DA US 3575879 A US3575879 A US 3575879A
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United States
Prior art keywords
radiation
luminescent material
luminescent
octaborate
bivalent europium
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Expired - Lifetime
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US823347A
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English (en)
Inventor
George Blasse
Jaap De Vries
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US Philips Corp
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US Philips Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/38—Devices for influencing the colour or wavelength of the light
    • H01J61/42—Devices for influencing the colour or wavelength of the light by transforming the wavelength of the light by luminescence
    • H01J61/44—Devices characterised by the luminescent material
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
    • C09K11/7728—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing europium
    • C09K11/774—Borates

Definitions

  • the invention relates to a low-pressure mercury vapour discharge lamp including a luminescent material provided on a support, which luminescent material can be excited by ultraviolet radiation. Furthermore the invention relates to such a material.
  • a document is copied by irradiating the master and directing the radiation which has been reflected or transmitted to a piece of paper which is sensitive to this radiation and contains substances which can be decomposed by the radiation so that a copy of the master document is obtained possibly after further treatment, for example, fixing.
  • a requirement generally imposed on the reproduction papers to be used is that the substances which are sensitive to radiation are converted as little as possible by normal daylight. This of course facilitates working with these papers and also imposes few requirements on the storage thereof. Since normal daylight contains comparatively little ultraviolet radiation the best combination is apparently a paper which has a maximum sensitivity below 400 nm. and a radiation source which emits a strong ultraviolet radiation.
  • the master to be copied must transmit or reflect the radiation. It has been found that many documents are made from paper which transmits and/ or reflects ultraviolet radiation comparatively poorly. In view of the contradictory requirements for documentcopying machines a compromise must therefore be made; it is therefore preferred to use light-sensitive papers the maximum sensitivity of which lies between 380 and 440 nm. and a radiation source having a maximum of the emitted radiation between these two values.
  • Document-copying machines generally use as radiation sources mercury vapour discharge lamps including a luminescent layer provided on a support which layer converts a great part of the ultraviolet radiation produced in the mercury vapour discharge into radiation of longer wavelength.
  • the maximum emitted radiation energy must preferably be in the wavelength range between 380 and 440 nm. This is, for example, the case with the very frequently used substance, calcium tungstate.
  • the conversion etficiency of the ultra violet radiation of the mercury vapour discharge into the radiation between 380 and 440 nm. is, however, comparatively small for this substance, because the emission spectrum is very wide and hence much radiation energy is emitted at wavelengths outside this range.
  • the absorption spectrum of most light-sensitive papers is con- Patented Apr. 20, 1971 siderably narrower than this range. As a result of these two causes only a comparatively small part of the total radiation energy emitted by the calcium tungstate is efficiently used by the sensitive paper.
  • a further luminescent substance which is very frequently used, is a lead-activated silicate of strontium, barium and magnesium.
  • the emission spectrum of this substance is not very wide when excited by the ultraviolet radiation of a mercury vapour discharge, and hence is more suitable for adaptation to the absorption spectrum of a radiation-sensitive paper; the maximum emission of this substance lies, however, at 355 nm. and is therefore less suitable to be transmitted or reflected by the paper of most documents. In spite of this fact the substance is very frequenly used on account of the narrow emission band and the strong radiation.
  • a low-pressure mercury vapour discharge lamp includes a luminescent material provided on a support and is characterized in that this luminescent material is an alkaline earth borate activated by bivalent europium and having the following composition wherein 0 x+y 0.l5 O yQOS 0.003 51150.05
  • a luminescent material which is represented by the above formula can be excited satisfactorily by ultraviolet radiation which is emitted by a low-pressure mercury vapour discharge lamp and the material then shows an emission spectrum in which the greater part of the luminescent energy is radiated between 380 and 440 nm. Since the conversion efiiciency is also very high, namely considerably higher than that of calcium tungstate and approximately as high as that of the above-mentioned silicate, a lamp according to the invention is more suitable for use in document-copying apparatus in combination with available radiation-sensitive types of paper having a maximum absorption within this range, because all requirements as set above are now simultaneously satisfied.
  • the substances according to the invention have a good temperature dependence, that is to say, their conversion efiiciencies decrease only slightly as the temperature increases. They are thus very suitable for use in high-power low-pressure mercury vapour discharge lamps whose wall temperature assumes a high value during operation.
  • a luminescent material according to the invention consists of a barium octaborate activated by bivalent europium wherein the barium may be partly replaced by strontium and/or calcium.
  • the luminescent properties do not substantially change when replacing small quantities of barium by strontium and/or calcium.
  • the maximum in the emission spectrum for all materials according to the invention lies at the same wavelength, namely at approximately 400 nm.
  • luminescent materials are known from United States patent specification No. 2,920,046 which have a fundamental lattice according to the formula aMeO.bB O wherein Me is at least one of the metals calcium, strontium, barium and cadmium and wherein the ratio a/b has a value between /2 and
  • the substances mentioned in the said patent specification are activated by manganese together with lead and/or bismuth.
  • the known substances do not, however, emit in the blue part, but in the green and yellow parts of the spectrum.
  • the amount of bivalent europium may be varied between the above-mentioned limits, but is preferably chosen A mixture was made of the substances indicated in column III of the table in the quantities indicated in column IV. Since the boric acid partly evaporates during the reaction, an excess of H BO of approximately 20% relative to the stoichiometric quantity is always used.
  • the hydrogen serves they are then often exposed for a short period to a heat for reducing the trivalent europium to bivalent europium. treatment in air at a fairly high temperature, for ex- After cooling subsequent to the second heat treatment ample, 600 C. Such a heat treatment is necessary, for the reaction product obtained was ground and sieved, example, when an organic binder is used which is to be if necessary. The product was then ready for use. removed later on by a heat treatment.
  • the quantum efficiency q is given in column V of A special advantage of a luminescent material accordthe table in percent. The percentages indicated show the ing to the present invention is that a light-reflecting layer conversion eificiencies of the absorbed exciting quantums.
  • the absorption factor is supposed charge lamps is known. This light-reflecting layer, which to be equal to l-r, wherein r represents the reflection is provided between the support of the luminescent matefactor. rial and the luminescent material, very strongly reflects The absorption factor is indicated in column VI. The visible radiation emitted by the luminescent material.
  • FIG. 1 diagrammatically shows a low-pressure mercury i f 1 p Sma u vapour discharge lamp according to the invention
  • FIG. 2 is a graphic representation of the radiation 1 3 ca e g t is re acts P Stan 40 intensity of the substance of Example 2 of the table, and 8 no ⁇ 3 5 0W a Wavelength of apProxfmately of two known substances, as a function of the wavelength,
  • FIG. 3 is a graphic representation of the variation of ten s s 1g t y urther, namely down to a waveleng h of the radiation intensity of the substance of Example 2 with approximately 380 nm.
  • FIG. 1 shows a low-pressure mercury vapour discharge accordmg to lnventlon a reflecting tltanlum f f lamp which includes an envelope 1.
  • Electrodes 2 and 3 l y y be f1'111tfu 11Y pal'tlcularly tltanlum dlOXlde between which the discharge takes place during operam the anatase modificat on, because at least the greater hon f the lamp are provided at the ends of the lamp part of theradiation emitted from the luminescent mate-
  • the inner Side f the envelope 1 which is made f f r131 15 Wlthm reflection range of f tltalflllm tiloXlde example, glass, is coated with a luminescent layer 4 which Some embod ments of the present invention will now contains a luminescent material according to the present he described with reference to one table, the following invention.
  • the luminescent substance is provided on the example and the accompanying diagrammatic drawing. envelope 1 in any conventional manner.
  • luminescent materials which are used in lamps according to the present invention have a more favourable location of the maximum emission in the spectrum as compared with the known silicate, while they have considerably higher peak values and a narrower emission range as compared with the known calcium tungstate.
  • the curve 2 in the graph of FIG. 3 shows the temperature dependence of the radiation intensity of the material of Example 2.
  • the temperature is plotted in C. on the abscissa.
  • the maximum intensity is fixed at 100.
  • the figure shows that the borates according to the invention have a very good temperature dependence and still show an intensity of the luminescent radiation at approximately 220 C. which is equal to half the maximum value. It may be noted for comparison that already at 75 C. the intensity of the known calcium tungstate has decreased to half the value at room temperature.

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  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Luminescent Compositions (AREA)
  • Vessels And Coating Films For Discharge Lamps (AREA)
US823347A 1968-05-10 1969-05-09 Bivalent europium activated barium octaborate luminescent material Expired - Lifetime US3575879A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL6806648A NL6806648A (enrdf_load_stackoverflow) 1968-05-10 1968-05-10

Publications (1)

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US3575879A true US3575879A (en) 1971-04-20

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US823347A Expired - Lifetime US3575879A (en) 1968-05-10 1969-05-09 Bivalent europium activated barium octaborate luminescent material

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US (1) US3575879A (enrdf_load_stackoverflow)
BE (1) BE732774A (enrdf_load_stackoverflow)
FR (1) FR2008204A1 (enrdf_load_stackoverflow)
GB (1) GB1192730A (enrdf_load_stackoverflow)
NL (1) NL6806648A (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4185222A (en) * 1978-01-13 1980-01-22 U.S. Philips Corporation Luminescent bivalent europium-activated barium borophosphate and discharge lamp containing the same
US4319161A (en) * 1979-07-23 1982-03-09 U.S. Philips Corporation Luminescent screen and low pressure mercury vapor discharge lamp containing the same
CN115340865A (zh) * 2022-08-24 2022-11-15 唐山学院 一种可见近红外发光材料及其制备方法

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL178549C (nl) * 1975-11-28 1986-04-01 Philips Nv Luminescerend scherm; lagedrukkwikdampontladingslamp; werkwijze voor de bereiding van een aardalkalimetaaltetraboraat.
FR2597851B1 (fr) * 1986-04-29 1990-10-26 Centre Nat Rech Scient Nouveaux borates mixtes a base de terres rares, leur preparation et leur application comme luminophores
FR3145343B1 (fr) 2023-01-26 2025-02-21 Safran Aerosystems Procédé de discrimination de conditions givrantes par apprentissage automatique

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4185222A (en) * 1978-01-13 1980-01-22 U.S. Philips Corporation Luminescent bivalent europium-activated barium borophosphate and discharge lamp containing the same
US4319161A (en) * 1979-07-23 1982-03-09 U.S. Philips Corporation Luminescent screen and low pressure mercury vapor discharge lamp containing the same
CN115340865A (zh) * 2022-08-24 2022-11-15 唐山学院 一种可见近红外发光材料及其制备方法
CN115340865B (zh) * 2022-08-24 2024-04-26 唐山学院 一种可见近红外发光材料及其制备方法

Also Published As

Publication number Publication date
BE732774A (enrdf_load_stackoverflow) 1969-11-10
FR2008204A1 (enrdf_load_stackoverflow) 1970-01-16
DE1919071B2 (de) 1976-11-25
DE1919071A1 (de) 1969-11-27
NL6806648A (enrdf_load_stackoverflow) 1969-11-12
GB1192730A (en) 1970-05-20

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