518 results about "Yttrium aluminium garnet" patented technology

The invention relates to a light source (1), having at least one LED (2) for emitting a primary radiation (4) and at least one luminescence conversion body (3) having at least one luminescent material for converting the primary radiation (4) into a secondary radiation (5). The luminescence conversion body is a polycrystalline ceramic body. The LED is based on GaInN and emits blue primary radiation. The ceramic body comprises for example a luminescent material based on a cerium-doped yttrium aluminum garnet. This luminescent material emits yellow secondary radiation. Blue primary radiation and yellow secondary radiation penetrate through the luminescence conversion body and are perceived as white light by the observer. In order to produce the luminescence conversion body, provision is made of a polycrystalline ceramic body which is united with a solution of a dopant. By means of a thermal treatment, the dopant (activator) diffuses into the ceramic body, the luminescent material being formed.

A member used within a plasma processing apparatus and exposed to a plasma of a halogen gas such as BCl₃ or Cl₂ is formed from a sintered body of metals of Group IIIa of Periodic Table such as Y, La, Ce, Nd and Dy, and Al and/or Si, for example, 3Y₂O₃.5Al₂O₃, 2Y₂O₃.Al₂O₃, Y₂O₃.Al₂O₃ or disilicate or monosilicate, and in particular, in this sintered body, the content of impurity metals of Group IIa of Periodic Table contained in the sintered body is controlled to be 0.15 wt % or more in total. Specifically, for this member, an yttrium-aluminum-garnet sintered body having a porosity of 3% or less and also having a surface roughness of 1 μm or less in center line average roughness Ra is utilized.

An erosion-resistant article for use as a component in plasma process chamber. The erosion-resistant article comprises a support and an oxide coating comprising yttrium, which is disposed over the support. The support and the oxide coating preferably have material compositions that differ from one another in coefficient of thermal expansion by no more than 5x10<-6>/K. Preferred oxide coating compositions include yttria and yttrium aluminum garnet. Preferred supports include alumina supports and aluminum-silicon carbide supports.

A thermal barrier coating system on a base material includes a bond coat layer with a lower face in direct contact with the base material and an upper face, a first ceramic layer in direct contact with the upper face of the bond coating layer and a second ceramic layer disposed on an outermost surface of the coating system and configured to be exposed to hot gas. The first ceramic layer includes a layer, combination, mixture, alloy, blend or multilayer structure of at least one of yttria-stabilized zirconia with a yttria content in a range of 6-8 wt-%, YTaO4 doped zirconia, and titania doped zirconia. The second ceramic layer includes a layer, combination, mixture, alloy, blend or multilayer structure of at least one of YTaO4 doped zirconia, titania doped zirconia, scandia stabilized zirconia, ceria containing perovskite material, yttrium aluminium garnet material, Monazite material, and spinel material. A material of the second ceramic layer is different from a material of the first ceramic layer.

The invention relates to a method for preparing rare earth-doped yttrium aluminum garnet transparent ceramic. In the invention, high-transparency polycrystalline ceramic is prepared by using commercial powdered Y2O3, Al2O3 and Re2O3, of which the purities are over 99.9 percent, as main raw materials and by spray granulation dry pressing molding process and vacuum reaction and sintering, wherein the Re may be one or several of trivalent rare earth elements such as Nd<3+>, Yb<3+>, Cr<3+>, Er<3+>, Ce<3+>, Sm<3+> and Eu<3+>; MgO or CaO or tetraethyl orthosilicate (TEOS) or SiO2 is used as a sintering assistant; a certain amount of bonding agent, plasticizer and dispersant is added; the oxides, sintering assistant and additive are mixed and added into a liquid medium, and the mixture is ball-milled and mixed for 0.5 to 100 hours; after the powder materials are mixed uniformly, the powder is made into spherical or approximately spherical grains; blanks formed by drying pressing isostatic forming are degreased; sintering the blanks in a vacuum sintering furnace; and annealing after sintering. The transmissivity at a laser wavelength of the rare earth-doped yttrium aluminum garnet transparent ceramic prepared by the method is more than or equal to 77 percent.

Disclosed herein are emissive ceramic materials having a dopant concentration gradient along a thickness of a yttrium aluminum garnet (YAG) region. The dopant concentration gradient may include a maximum dopant concentration, a half-maximum dopant concentration, and a slope at or near the half-maximum dopant concentration. The emissive ceramics may, in some embodiments, exhibit high internal quantum efficiencies (IQE). The emissive ceramics may, in some embodiments, include porous regions. Also disclosed herein are methods of make the emissive ceramic by sintering an assembly having doped and non-doped layers.

The present invention pertains to a process for synthesizing nano-scale yttrium aluminum garnet (YAG) fluorescent powders having formula (I):

(Y_3−xR¹_x)(Al_5−yR²_y)O₁₂  (I)

wherein R¹ and R² are independently selected from the elements consisting of rare earth metals and transition metals, and each of x and y is independently a value between 0 and 1.5, where the process comprises the steps:

• • (a) forming an aqueous solution comprising rare earth metal ions, transition metal ions, yttrium ion and aluminum ion;
  • (b) adding a precipitating agent to the aqueous solution of step (a) in an amount sufficient to allow the rare earth metal ions, transition metal ions, yttrium ion and aluminum ion comprised in the aqueous solution to substantially complex with the depositing agent;
  • (c) drying the gel of step (b) to obtain a dried gel;
  • (d) adding a dehydroxying compound to the dried gel of step (c) and subjecting it to a further drying step; and
  • (e) sintering the product of step (d) at a temperature between 700 and 1400° C. to obtain the nano-scale yttrium aluminum garnet fluorescent powders of formula (I).

The invention discloses a method for preparing rare earth ion-doped yttrium-aluminum garnet (Re: YAG) transparent laser ceramic by using hot-pressing post treatment. The method comprises the steps of using oxide powder as a raw material, mixing with a ball mill, drying, forming, performing cold isotactic processing to obtain a ceramic biscuits, then dumping, and carrying out vacuum sintering to obtain the Re: YAG ceramic; and performing powder-embedded hot pressing, annealing and optically polishing on the Re: YAG ceramic to obtain the final Re: YAG transparent laser ceramic. The method provided by the invention has the advantages of strong controllability and repeatability, and low cost, and the Re: YAG transparent ceramic prepared by the method provided by the invention has high transmittance.

Synthesis of yttrium aluminum garnet luminescent material for white light LED is carried out by proportioning by chemical component formula (Y1-x-yMyCex) 3Al5O12, weighing raw material, mixing with flux additive, putting into corundum crucible, firing in oxidation atmosphere furnace, crushing, mesh screening, acid washing by dilute nitric acid solution to indifference, extraction filtering, drying powders, firing the powder at reduction atmosphere, and screen grading to obtain the final product. It uses two kinds or above of boric acid, barium fluoride, strontium fluoride, lithium chloride or lithium fluoride as composite flux and mixes with other rare earth or metal oxide. It has excellent single crystal particular growth, powder fluidity, better brightness and low decrement.

The invention provides a method for preparing yttrium aluminium garnet (YAG) transparent ceramic with a composite structure. The method comprises the following steps: by using Re:YAG powder and high-purity Y2O3, Al2O3 and Re2O3 as raw materials, adding a certain amount of dispersing agent, binder, plasticizer and defoaming agent to mix slurry in a ball-milling manner; preparing different doped and bound composite structures of ceramic biscuits, such as Sm:YAG/Nd:YAG, Cr:YAG/Yb:YAG and YAG/Nd:YAG, different multi-segment doped Re:YAG ceramic biscuits, such as YAG/Cr:YAG/Nd:YAG/YAG, a core-shell structured composite ceramic biscuit, and a layered composite structure of transparent ceramic biscuit in a vacuum pressure slip casting manner. Different composite structures of Re:YAG transparent ceramics are obtained by the following processing steps: biscuit degreasing, vacuum sintering, hot isostatic pressing sintering, annealing and the like. The linear transmittance of the transparent ceramic after being polished at double sides in a visible near infrared region can be up to over 80%.

The invention discloses a preparation method of yttrium aluminium garnet doped transparent laser ceramics. The method includes using an alcohol-aqueous system stepping chemical co-precipitation method to firstly prepare high-dispersity and high-activity nanometer Y2O3 oxide powders, Al2O3 oxide powders and rare earth (Re) oxide powders, weighing raw materials of the powders according to a stoichiometric ratio of Y<3-x>RexAl5O12 when the powders are prepared, placing the powders, sintering aids, dispersing agents and absolute ethyl alcohol into a ball-milling tank for ball milling, drying ball-milling mixing slurries into powders, forming the powders into green bodies with certain shapes by dry pressing, and then subjecting the green bodies to isostatic cool pressing to obtain ceramic biscuits. The ceramic biscuits are subjected to binder removing, vacuum sintering, powder-burying hot-pressing post-processing, annealing and optical polishing to obtain Re:YAG transparent ceramics. The preparation method has the advantages of being controllable, high in repeatability, low in cost and high in transmittance.

A transparent yttrium aluminum garnet precursor composition is provided that includes a plurality of calcined particles of yttrium aluminum oxide having a mean particle domain size of between 10 and 200 nanometers and a predominant hexagonal crystal structure. High levels of YAG transparency are obtained for large YAG articles through control of the aluminum:yttrium atomic ratio to 1:06±0.001 and limiting impurity loadings to less than 100 ppm. The composition is calcined at a temperature between 700° Celsius and 900° Celsius to remove organic additives to yield a predominant metastable hexagonal phase yttrium aluminum oxide nanoparticulate having an atomic ratio of aluminum: yttrium of 1:0.6±0.001. With dispersion in an organic binder and a translucent YAG article is formed having a transmittance at a wavelength of 1064 nanometers of greater than 75%. The translucent YAG article is characterized by an average domain size of less than 1 micron and having a density of at least 99% and inclusions present at less than 2 surface area percent. The ability of a batch of yttrium aluminum oxide nanoparticles to serve as a transparent YAG precursor includes collecting an X-ray fluorescence spectrum from a plurality of aluminum oxide nanoparticles having a predominant crystal structure other than garnet to yield an A1:Y raw integrated peak intensity ratio. The nanoparticles are sintered to yield a predominant garnet phase and a secondary phase and optionally isostatic pressing during sintering. By using only precursor nanoparticles with a standard deviation of ±0.003 in the peak ratio exceptionally high transparency YAG is reproducibly produced.

The present invention relates to a semiconductor illumination white light emitting diode fluorescence powder and its preparation method. Said fluorescence powder is yttrium aluminium garnet fluorescence powder activated by cerium. Said invention also provides its chemical molecular formula. Its preparation method includes the following steps: selecting raw material whose purity is 4-5 N and grain size is 1-2 micrometers, preparing precursor body, adding fusing agent which is selected from BaF2+H3BO3, after the fluorescence powder is synthesized, making after-treatment, acid-washing, alkali-washing, water-washing, pulverizing, sieving and finished product detection, its lumen efficiency can be up to 33-401 m/w.

An integrated sintered body is provided having at least a first phase and a second phase. The first phase includes alumina as a main component, and the alumina contains a total amount of 12 weight percent or more and 50 weight percent or less of one or more of stabilized zirconia and partially stabilized zirconia. The second phase contains yttrium-aluminum garnet as a main component.

The invention provides a coprecipitation preparation method of rare earth-doped yttrium aluminium garnet fluorescent powder. The chemical formula of the fluorescent powder is LnaMbO12:Rx,R'y, wherein Ln is at least one of Sc, Y, Pr, Nd, Gd, Dy and Sm; a is more than or equal to 2.8 and less than or equal to 3.2; M is at least one of Al and Ga, and b is more than or equal to 4.9 and less than or equal to 5.1; R is at least one of Ce and Tb, and x is more than or equal to 0.01 and less than or equal to 0.2; and R' is at least one of Pr and Dy, and y is more than or equal to 0 and less than or equal to 0.1. The coprecipitation preparation method comprises the following steps: preparing a metal ion mixed liquid and preparing nano doped cerium yttrium aluminium garnet crystal seeds; adding the crystal seeds and a dispersing agent to a precipitator, thus obtaining a mixed solution; dropwise adding the metal ion mixed liquid into the mixed solution so as to obtain an intermediate product, and carrying out water washing, alcohol leaching and drying on the intermediate product; adding a fluxing agent in the intermediate product, and then roasting under the reducing atmosphere; and carrying out gas stream smashing, impurity removal, drying and grading on a product of roasting, thus obtaining the rare earth-doped yttrium aluminium garnet fluorescent powder. The shape of the product is regular, the particle diameter (d50) of the product is 1-10 mu, and the product has the advantages of stable property and good luminescence performance, and can be effectively excitated by blue light.

The invention discloses a making method of fluorescent powder of yttrium aluminium garnet, which comprises the following steps: allocating certain quantity of alumina powder, yttrium nitrate, cerous nitrate and gadolinium nitrate into sediment mother liquid; allocating sediment agent solution through at least one of NaOH, NH3.H2O or NH3HCO3; maintaining sediment mother liquid temperature between 10 and 70 deg.c; stirring evenly; adding sediment agent solution into sediment mother liquid; stopping adding sediment agent when pH value is 6.8-11; insulating and stirring; separating solid from liquid of sediment mother liquid; washing solid through clean water; drying; adding fluoride in the powder as reacting adjuvant; placing blended powder into high-temperature stove; heating protected by gas; cooling; obtaining sintered fluorescent powder bulk; grinding; sieving; obtaining the product.

The invention provides a method for preparing yttrium aluminum garnet-based transparent ceramic through aqueous tape casting. The method comprises steps: preparing a slurry of the yttrium aluminum garnet-based transparent ceramic and a casting film by adopting water as a solvent through adopting an aqueous tape casting technology; processing the casting film to form diaphragms having different shapes as needed; carrying out lamination treatment of the diaphragms at a lamination temperature of 75-95DEG C under a lamination pressure of 40-120MPa to obtain a biscuit; and carrying out degumming treatment and cold isostatic pressing treatment of the biscuit, and sintering to obtain the yttrium aluminum garnet-based transparent ceramic. The method has a good environmental compatibility, and the transparent ceramic can be obtained through the method.