EP0242381A1 - Yttrium aluminium garnet phosphor deposition technique - Google Patents
Yttrium aluminium garnet phosphor deposition techniqueInfo
- Publication number
- EP0242381A1 EP0242381A1 EP19860906066 EP86906066A EP0242381A1 EP 0242381 A1 EP0242381 A1 EP 0242381A1 EP 19860906066 EP19860906066 EP 19860906066 EP 86906066 A EP86906066 A EP 86906066A EP 0242381 A1 EP0242381 A1 EP 0242381A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- particles
- phosphor
- substrate
- heating
- yag
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Ceased
Links
Classifications
-
- 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
- C09K11/02—Use of particular materials as binders, particle coatings or suspension media therefor
Definitions
- This invention relates to cathodoluminescent phosphors and, more particularly, to yttrium aluminum garnet (YAG; Y 3 Al 5 O 12 ) phosphors.
- the thermal conduction process limits the brightness of the CRT. More specifically, in order to increase the brightness of a CRT display, the electron current density is increased, which in turn increases th'e temperature of the phosphor layer.
- the cathodoluminescence of powder phosphors exhibit a thermal quenching effect at high temperatures. For example, in a YAG phosphor the cathodoluminescence is significantly reduced above a quench temperature of ⁇ 300°C.
- the amount of electron beam energy that can be usefully deposited in the ohosphor layer is limited by its thermal conductivity. In order to achieve CRTs of greater luminosity, therefore, phosphor layers of higher thermal conductivity are needed.
- a high temperature reaction is performed between YAG particles and sulfuric acid.
- the reaction produces sulfate compounds which serve as a binder between YAG particles themselves as well as between the
- YAG particles react with sulphuric acid at elevated temperatures to form sulphate compounds which bind the YAG particles to one another and to the substrate.
- the packing density of the YAG phosphor layer is increased; that is, the contact area between the particles and the substrate is increased, thereby enhancing the thermal conductivity of the phosphor layer.
- the cathodoluminescence is about
- our technique entails providing a suitable substrate, treating phosphor YAG particles with sulphuric acid, depositing the treated particles on the substrate, and heating to an elevated temperature in an oxygen ambient.
- the treated phosphor is preheated on the substrate at a lower temperature in air until dry before being subjected to the last heating step.
- the YAG particles constitute a phosphor; that is, they contain a suitable activator (dopant) to generate luminescence when impacted by an electron beam.
- Illustrative activators are Eu (red) and Ce (green).
- Suitable substrates comprise transparent materials such as quartz, non-browning glass, and sapphire.
- the preheating may take place at temperatures ranging from about 100°C to 200°C.
- the last heating step should take place at higher temperatures effective to form the desired sulphate compounds.
- This example describes the fabrication of a YAG phosphor using, as a starting material, YAG phosphor particles designated P53 which is a powder commercially available from United Mineral and Chemical Co., N.Y., M.Y. (manufactured by Derby Luminescents, Middlesex,
- Thermogravimetr ic analyses were made to study the weight changes during heating. TGA was performed using a commercially available thermal analysis system. Approximately 30 mg of the treated and dried phosphor YAG powders was loaded into a standard platinum boat, which was heated from 20°C to 900°C at a constant rate of 20°C per minute in a flowing air atmosphere. Weight loss measurements were recorded at 3 sec intervals. At the end of each run, computer analysis of the data gave the temperature and weight loss during the transition. pScanning electron microscopy was used to study the microstructures of the phosphor layer. The cathodoluminescent efficiency of the deposited phosphor layers was also evaluated in a scanning electron microscope.
- the electron gun produced a beam density on the order of 10 9 W/m 2 . Electron energies were varied between 5 kV and 30 kV. The electron beam scanned the samples in a single line or in a 256 line raster having a 66 ⁇ sec period line. Phosphor layers deposited in accordance with our invention and other layers deposited by a conventional settling technique were measured. The layers prepared by both procedures had a thickness of about 75 ⁇ m. The phosphor layers were covered with a 120 nm thick Al coating to prevent charging of the phosphor and also to enhance the luminous output. Light generated in the phosphor layers was transmitted through the substrate and was focused by a lens to a photomultipler. The light intensity was measured with a commercially available radiometer.
- H 2 SO 4 -treated YAG phosphor layers each heated 1.25 h in O 2 at different temperatures: 1080°C, 997°C, 642°C, and 330°C.
- XRD data showed that our H 2 SO 4 - treated YAG phosphor layers had many extra non-garnet peaks with high intensities in samples heat-treated at 330°C and 642°C . We bel ieve that these ex tra peaks are due to the sulfate compounds created by high temperature reactions between the garnet phase and H 2 SO 4 .
- H 2 SO 4 to form some sulfate compounds.
- Such a high concentration of sulfate compounds in sample heat at 300°C to 700°C is consistent with the high XRD peak intensities of the sulfate compounds.
- the latter can take on forms other than Y 3 Al 5 (SO 4 ) 12 , such as Y 2 (SO 4 ) 3 and Al 2 (SO 4 ) 3 , including hydrated forms thereof.
- SEM micrograph were taken of YAG phosphor layer deposited by our technique on sapphire substrates and heat at 550°C for 1.25 h in O 2 .
- One micrograph showed enhanced contact area between the phosphor layer and the substrate, which allowed for efficient heat dissipation.
- Another micrograph of the same specimen, but with a tilt angle of 68.5 degree showed large contact area between phosphor particles.
- Yet another micrograph of the cross-section of the phosphor layer illustrated the 2 ⁇ m phosphor particles held together in a continuous network by some sulfate binder phases.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Luminescent Compositions (AREA)
Abstract
Substance phosphorescente utilisée dans des tubes à rayons cathodiques et comprenant des particules de ferrite grenat d'yttrium-aluminium liées entre elles et à un substrat par un composé de sulfate. La substance phosphorescente est préparée en traitant les particules de ferrite grenat d'yttrium-aluminium avec de l'acide sulfurique, en déposant la poudre traitée sur un substrat non brunissant en verre, quartz ou saphir, et en chauffant ladite poudre à une température comprise entre 320o C et 780o C environ pendant une à deux heures en présence d'oxygène.Phosphorescent substance used in cathode ray tubes and comprising yttrium-aluminum garnet ferrite particles bonded together and to a substrate by a sulfate compound. The phosphorescent substance is prepared by treating the yttrium-aluminum garnet ferrite particles with sulfuric acid, by depositing the treated powder on a non-browning substrate in glass, quartz or sapphire, and by heating said powder to a temperature comprised between 320o C and 780o C approximately for one to two hours in the presence of oxygen.
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US78684385A | 1985-10-11 | 1985-10-11 | |
US786843 | 1985-10-11 |
Publications (1)
Publication Number | Publication Date |
---|---|
EP0242381A1 true EP0242381A1 (en) | 1987-10-28 |
Family
ID=25139741
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19860906066 Ceased EP0242381A1 (en) | 1985-10-11 | 1986-09-11 | Yttrium aluminium garnet phosphor deposition technique |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0242381A1 (en) |
JP (1) | JPS63501083A (en) |
WO (1) | WO1987002374A1 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
IL92011A0 (en) * | 1988-10-19 | 1990-07-12 | Abbott Lab | Heterocyclic peptide renin inhibitors |
DE102013109313A1 (en) | 2013-08-28 | 2015-03-05 | Leuchtstoffwerk Breitungen Gmbh | Improved garnet phosphor and process for its preparation |
-
1986
- 1986-09-11 EP EP19860906066 patent/EP0242381A1/en not_active Ceased
- 1986-09-11 JP JP50529986A patent/JPS63501083A/en active Pending
- 1986-09-11 WO PCT/US1986/001878 patent/WO1987002374A1/en not_active Application Discontinuation
Non-Patent Citations (1)
Title |
---|
See references of WO8702374A1 * |
Also Published As
Publication number | Publication date |
---|---|
JPS63501083A (en) | 1988-04-21 |
WO1987002374A1 (en) | 1987-04-23 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): DE FR GB IT NL SE |
|
17P | Request for examination filed |
Effective date: 19870924 |
|
17Q | First examination report despatched |
Effective date: 19881212 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION HAS BEEN REFUSED |
|
18R | Application refused |
Effective date: 19890626 |
|
RIN1 | Information on inventor provided before grant (corrected) |
Inventor name: YAN, MAN, FEI Inventor name: HUO, TAI-CHAN, DONALD |