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Luminophore and core-shell luminophore precursors

A technology for luminescent materials and precursors, applied in the field of preparing this new type of luminescent materials, can solve the problem of high cost and achieve the effect of reducing costs

Inactive Publication Date: 2009-07-22
RHODIA OPERATIONS SAS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, in addition to its various advantages, there is still a problem, namely its high cost, which is especially related to the use of terbium

Method used

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  • Luminophore and core-shell luminophore precursors
  • Luminophore and core-shell luminophore precursors
  • Luminophore and core-shell luminophore precursors

Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0188] In the following examples, the prepared particles were characterized by particle size, morphology and composition by the following methods.

[0189] particle size measurement

[0190] Using a laser particle size analyzer (Malvern 2000), particle diameters were measured on particle samples dispersed in water and subjected to ultrasound (130W) for 1 minute and 30 seconds.

[0191] electron microscopy

[0192] Transmission electron micrographs were obtained on particle sections (microsection method) using a high-resolution JEOL 2010 FEG-type TEM microscope. The spatial resolution of the device for measuring chemical composition by EDS (Energy Dispersive Spectroscopy) is less than 2 nm. Correlation of the observed morphology with the measured chemical composition demonstrates the core-shell structure and allows measurement of shell thickness on micrographs.

[0193] Determination of chemical composition by EDS was achieved by X-ray diffraction analysis of photographs...

Embodiment 1

[0200] Example 1 : LaPO 4 Synthesis of nuclear precursors

[0201] To 500ml of phosphoric acid H which had been brought to pH 1.6 by adding ammonia water and heated to 60°C over one hour 3 PO 4 Add 500ml of lanthanum nitrate solution (1.5mol / l) to the solution (1.725mol / l). During the precipitation the pH was adjusted to 1.6 by adding ammonia.

[0202] At the end of the precipitation step, the reaction medium is maintained at 60° C. for a further 1 h. The precipitate was then easily collected by filtration, washed with water, and then dried in air at 60°C. The obtained powder was then subjected to heat treatment at 900° C. in air.

[0203] Characterized by X-ray diffraction, the product thus obtained is lanthanum orthophosphate LaPO with monazite structure 4 . Particle size D 50 It is 5.2 μm and has a dispersion index of 0.6. The specific surface area S of the product measured by BET BET =6m 2 / g.

Embodiment 2

[0204] Example 2 : LaPO 4 Synthesis of nuclear precursors

[0205] After one hour, add ammonia water to make the pH value reach 1.9 and heat to 500ml phosphoric acid H at 60°C. 3 PO 4 Add 500ml of lanthanum nitrate solution (1.5mol / l) to the solution (1.725mol / l). During the precipitation the pH was adjusted to 1.9 by adding ammonia.

[0206] At the end of the precipitation step, the reaction medium is maintained at 60° C. for a further 1 h. The precipitate was then easily collected by filtration, washed with water, and then dried in air at 60°C. The obtained powder was then subjected to heat treatment at 900° C. in air.

[0207] Characterized by X-ray diffraction, the product thus obtained is lanthanum orthophosphate LaPO with monazite structure 4 . Particle size D 50 It is 4.3 μm and has a dispersion index of 0.4.

[0208] The powder was then calcined in air at 1100 °C for 2 h. Thus the particle size D 50 Rare earth phosphate with a diameter of 4.9 μm, a dispers...

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Abstract

The present invention relates to a new type of green luminophore composed of mixed rare-earth phosphates, and a method of preparation of these new luminophores from precursors comprising particles having a mean diameter of between 1.5 and 15 microns, these particles comprising an inorganic core and a shell composed of a mixed lanthanum and / or cerium phosphate, optionally doped with terbium, evenly covering the inorganic core with a thickness greater than or equal to 300 nm.

Description

technical field [0001] The present invention relates to a new type of green luminophores based on mixed phosphates of lanthanum and / or cerium doped with terbium, and to a process for the preparation of such new luminophores. Background technique [0002] Mixed phosphates of cerium and / or lanthanum doped with terbium (will be denoted herein by their common acronym "LAP") are well known compounds which generally have lanthanum phosphate LaPO 4 structure in which at some sites the lanthanum cations are replaced by terbium cations and at other sites the lanthanum may be fully or partially replaced by cerium cations. In this context, mixed phosphates of lanthanum, terbium and cerium (hereinafter referred to as “cerium-containing LAP”) and mixed phosphates of lanthanum and terbium (hereinafter referred to as “cerium-free LAP”) may be mentioned in particular. The luminescent properties of these mixed phosphates are well known. More specifically, it emits bright green light when i...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C09K11/77H01J61/44
CPCC09K11/7777B01J14/00H01J61/44C09K11/025H01K1/04
Inventor T·勒-梅西耶V·比塞特
Owner RHODIA OPERATIONS SAS
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