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AssigneeNational Institute for Research in Inorganic Materials
InventorsYasuto Miyazawa, Masami Sekita, Shoji Morita, Hideyuki Sekiwa
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A method for producing a single crystal or polycrystal of terbium aluminate containing at least terbium, aluminum and oxygen and represented by the formula Tb.sub.1-x Al.sub.1+x O.sub.3 wherein -0.5.ltoreq.x.ltoreq.0.5, which comprises growing the single crystal or polycrystal using a reducing gas atmosphere or a neutral gas atmosphere as an atmosphere for crystal growth.
A method for producing a single crystal or polycrystal of terbium aluminate containing at least terbium, aluminum and oxygen and represented by the formula Tb.sub.1-x Al.sub.1+x O.sub.3 wherein -0.5.ltoreq.x.ltoreq.0.5, which comprises growing the single crystal or polycrystal by a bulk growth method without a flux in a reducing gas atmosphere or a neutral gas atmosphere.
A single crystal or polycrystal of terbium aluminate having a composition containing at least terbium, aluminum and oxygen and represented by the formula Tb.sub.1-x Al.sub.1+x O.sub.3 wherein -0.5.ltoreq.x.ltoreq.0.5, which exhibits a green or yellowish green emission in a visible wavelength region at room temperature,
A single crystal or polycrystal of terbium aluminate having a composition containing at least terbium, aluminum and oxygen and represented by the formula Tb.sub.1-x Al.sub.1+x O.sub.3 wherein -0.5.ltoreq.x.ltoreq.0.5, which has no absorption in a visible wavelength region other than absorption from .sup.7 F.sub.6 multiplet to .sup.5 D.sub.4 multiplet of terbium,
Dependencies are inferred from the claim text.
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No related US applications are recorded in the indexed filing history.
Single-crystal growth by zone-melting
Single-crystal growth by normal freezing or freezing under temperature gradient
Single-crystal growth by pulling from a melt
Oxides: aluminium oxides
Term ended 28 Jan 2014 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
1. Field of the Invention
The present invention relates to a method for producing a single crystal or polycrystal of terbium aluminate, which is useful as a luminescent material such as a laser material or a phosphor.
2. Discussion of Background
In the accompanying drawings:
FIG. 1 is a graph showing absorption spectra of TbAlO.sub.3 single crystals grown and annealed in various atmospheres.
FIG. 2 is a graph showing an emission spectrum of a TbAlO.sub.3 single crystal obtained in a reducing atmosphere in Example 1.
As mentioned above, the material according to the present invention is composed of a single crystal or polycrystal having a composition containing at least terbium, aluminum and oxygen and represented by the formula Tb.sub.1-x Al.sub.1+x O.sub.3 wherein -0.5.ltoreq.x.ltoreq.0.5. The emission color can be controlled, since the lattice constant can be controlled by adjusting the x value within this range. On the other hand, if the x value exceeds this range, other phases tend to precipitate in the crystal, such being undesirable.
In the above formula, the terbium site may be partly substituted by a Group IIIa element, or the aluminum site may be partly substituted by a Group IIIb element.
Now, the present invention will be described with reference to a composition of TbAlO.sub.3 (x=0) as an example. For example, the luminescent life time can be controlled by substituting a part of Tb by La as a Group IIIa element. It is generally known that with a luminescent material, as the concentration of the added optically active ions increases, the luminous intensity tends to be not proportional to the added amount, and the emission eventually ceases, and at the same time, the luminescent life time tends to be short (i.e. concentration quenching). The significance of the substitution in the present invention is totally different from the case of such a conventional phosphor, although when represented by a chemical formula, it may be similar to the case of the conventional phosphor.