JPH06293598A - Optical litao3 single crystal and its production - Google Patents
Optical litao3 single crystal and its productionInfo
- Publication number
- JPH06293598A JPH06293598A JP10189693A JP10189693A JPH06293598A JP H06293598 A JPH06293598 A JP H06293598A JP 10189693 A JP10189693 A JP 10189693A JP 10189693 A JP10189693 A JP 10189693A JP H06293598 A JPH06293598 A JP H06293598A
- Authority
- JP
- Japan
- Prior art keywords
- single crystal
- litao
- light
- wavelength
- hours
- 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.)
- Granted
Links
Landscapes
- Crystals, And After-Treatments Of Crystals (AREA)
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は光用LiTaO3単結晶、特に
は波長変換素子、光変調素子など、特に光を透過させて
使用する素子に有用とされる光透過性のすぐれたLiTaO3
単結晶およびその製造方法に関するものである。BACKGROUND OF THE INVENTION The present invention relates to a LiTaO 3 single crystal for light, particularly a LiTaO 3 having excellent light transmittance, which is particularly useful for a device for transmitting light, such as a wavelength conversion device and a light modulation device.
The present invention relates to a single crystal and a manufacturing method thereof.
【０００２】[0002]
【従来の技術】LiTaO3単結晶はテレビの中間波フィルタ
ーを初め、多くの表面弾性波デバイス用の基板として使
用されているが、このものは波長変換素子を始めとする
光学素子としてもその用途が急速に拡大されてきてい
る。しかして、このLiTaO3単結晶を製造する方法として
は、このLiTaO3単結晶の融点が 1,650℃であることか
ら、イリジウムまたは白金−ロジウム合金からなるるつ
ぼを使用して結晶を成長させる方法が一般的な方法とさ
れているが、イリジウム製るつぼを用いて大気雰囲気中
で育成すると酸化損耗が発生するし、これを窒素 100％
の不活性雰囲気とすると単結晶がねじれ易くなるという
不利があり、白金−ロジウム製のるつぼを使用する場合
にはロジウムがLiTaO3融液に溶け込むためにロジウムが
育成結晶中に混入して結晶が着色するという欠点があ
る。2. Description of the Related Art LiTaO 3 single crystal is used as a substrate for many surface acoustic wave devices such as an intermediate wave filter of a television, and this is also used as an optical element such as a wavelength conversion element. Is rapidly expanding. Thus, as a method for manufacturing the LiTaO 3 single crystal, since the melting point of the LiTaO 3 single crystal is 1,650 ° C., iridium or platinum - how to use a crucible made of rhodium alloy growing crystals generally However, if an iridium crucible is grown in an air atmosphere, oxidative wear will occur.
There is a disadvantage that the single crystal is easily twisted when the inert atmosphere of, platinum-rhodium when using a crucible made of rhodium is mixed into the LiTaO 3 melt to mix rhodium into the grown crystal crystal It has the drawback of being colored.
【０００３】そのため、このLiTaO3単結晶の製造方法に
ついては、イリジウム製るつぼを使用して 0.5〜 2.5容
量％の酸素を含む不活性ガス雰囲気下で育成する方法が
提案されており（特公平 4-11513号公報）、これについ
てはまたイリジウム製るつぼを使用して還元性または不
活性ガスに 0.2〜５重量％の酸素を含有させた混合ガス
中で育成するという方法も提案されている（特開昭63-2
1859号公報参照）。Therefore, as a method for producing this LiTaO 3 single crystal, there has been proposed a method of using an iridium crucible to grow it in an inert gas atmosphere containing 0.5 to 2.5% by volume of oxygen (Patent Publication 4). Japanese Patent Laid-Open No. 11513/11513), a method of using an iridium crucible and growing it in a mixed gas in which a reducing or inert gas contains 0.2 to 5% by weight of oxygen has also been proposed (special feature). Kaisho 63-2
(See the 1859 publication).
【０００４】[0004]
【発明が解決しようとする課題】しかし、この提案され
ている方法で 0.5〜 2.5容量％、 0.2〜５重量％の酸素
を添加した不活性ガス雰囲気でLiTaO3単結晶を育成する
と不純物や酸素欠陥による着色は防止されるとしても、
このような方法で育成されたLiTaO3単結晶は黄色い着色
が残るために、このものは補色である 400〜500nm の青
色を吸収し、光学素子、特に赤色光から青色光への波長
変換素子の発光効率が低下するので、波長変換素子用に
は不適当なものになるという欠点がある。However, when a LiTaO 3 single crystal is grown by this proposed method in an inert gas atmosphere containing 0.5 to 2.5% by volume of oxygen and 0.2 to 5% by weight of oxygen, impurities and oxygen defects are generated. Even if the coloring due to
Since the LiTaO 3 single crystal grown by such a method retains a yellow coloration, it absorbs the complementary color of 400 to 500 nm of blue color, and the optical element, especially the wavelength conversion element from red light to blue light, is used. Since the luminous efficiency is lowered, there is a drawback that it becomes unsuitable for a wavelength conversion element.
【０００５】[0005]
【課題を解決するための手段】本発明はこのような不
利、欠点を解決した光用LiTaO3単結晶およびその製造方
法に関するものであり、このLiTaO3単結晶は波長λ≧40
0nm における光吸収係数が0.08cm-1以下であることを特
徴とするものであり、この製造方法は引上げたLiTaO3単
結晶を還元性または不活性ガス雰囲気において、 700℃
以上で２時間以上熱処理することを特徴とするものであ
る。The present invention relates to an optical LiTaO 3 single crystal for solving the above disadvantages and drawbacks and a method for producing the same. The LiTaO 3 single crystal has a wavelength λ ≧ 40.
The light absorption coefficient at 0 nm is 0.08 cm -1 or less, and this manufacturing method uses a pulled LiTaO 3 single crystal at 700 ° C in a reducing or inert gas atmosphere.
The above is characterized by performing heat treatment for 2 hours or more.
【０００６】すなわち、本発明者らは光透過性のすぐれ
たLiTaO3単結晶を開発すべく種々検討した結果、このLi
TaO3単結晶については波長λ≧400nm における光吸収係
数が0.08cm-1以下であれば光透過性のすぐれたものにな
るということを見出すと共に、このような物性をもつLi
TaO3単結晶を得るためには引上げ法で作られたLiTaO3単
結晶を還元性または不活性ガス雰囲気中において 700℃
以上で２時間以上加熱処理すれば光透過性のよいものと
することができることを確認して本発明を完成させた。
以下にこれをさらに詳述する。That is, the present inventors have conducted various studies to develop a LiTaO 3 single crystal having excellent light transmittance, and as a result,
Regarding TaO 3 single crystal, it was found that the light transmittance is excellent if the light absorption coefficient at wavelength λ ≧ 400 nm is 0.08 cm −1 or less, and Li having such physical properties is also found.
In order to obtain TaO 3 single crystal, LiTaO 3 single crystal prepared by pulling method was used at 700 ℃ in reducing or inert gas atmosphere.
The present invention has been completed by confirming that heat treatment can be performed for 2 hours or more to obtain good light transmission.
This will be described in more detail below.
【０００７】[0007]
【作用】本発明は光透過性のすぐれたLiTaO3単結晶に関
するものであるが、LiTaO3単結晶については波長λが 4
00nmまたは 400nm以上である光を投射したときの光吸収
係数が0.08cm-1以下であれば光透過性のすぐれたもので
あるということが本発明者らによって見出された。The present invention relates to a LiTaO 3 single crystal having an excellent light transmittance, but the wavelength λ of the LiTaO 3 single crystal is 4
The present inventors have found that a light absorption coefficient of 0.08 cm −1 or less when projected with light having a wavelength of 00 nm or 400 nm or more has excellent light transmittance.
【０００８】この光吸収係数はある波長での入射光強度
をIo、単結晶透過後の強度をＩとし、Ｒを反射率、Ｋを
光吸収係数、ｌを単結晶の厚さとすると、このIoとＩと
の関係が Ｉ＝Io(l-R)exp (Kl) ・・・・・・・・・・・・・・（１） で示されるが、ここで吸光度Ｅを 吸光度Ｅ＝-log(I/Io)とおくと、この式（１）は Ｅ＝Kl/2.303-log(l-R) となり、単結晶の厚みを変えて吸光度をプロットしたと
きの直線の傾きが光吸収係数となるので、これについて
はこの吸光度を測定することによってこの光吸収係数を
求めればよい。The light absorption coefficient is Io, where Io is the intensity of incident light at a certain wavelength, I is the intensity after passing through a single crystal, R is the reflectance, K is the light absorption coefficient, and l is the thickness of the single crystal. The relation between I and I is shown as I = Io (lR) exp (Kl) ..... (1), where the absorbance E is the absorbance E = -log (I / Io), this formula (1) becomes E = Kl / 2.303-log (lR), and the slope of the straight line when the absorbance is plotted by changing the thickness of the single crystal is the light absorption coefficient. For, the light absorption coefficient may be determined by measuring the absorbance.
【０００９】なお、吸光度については後記する本発明の
LiTaO3単結晶の製造方法にしたがって引上げ法で作った
結晶厚みが９mmのLiTaO3単結晶を窒素ガス雰囲気中にお
いて910℃で16時間熱処理したもの（資料Ａ）と、比較
のために大気中において 910℃で16時間熱処理したもの
（資料Ｂ）の分光特性をしらべたところ、吸光度（縦
軸）、波長（横軸）について図１に示したとおりの結果
が得られ、波長が 400nm以上のところでは、Ａ、Ｂ共に
400nmで吸収より大きな吸収はないが、ＡのほうがＢよ
りも測定波長域で吸収が少なく、特に 400nm付近では顕
著に吸収の小さいことが確認された。[0009] The absorbance of the present invention described later
A LiTaO 3 single crystal with a crystal thickness of 9 mm, which was produced by the pulling method according to the method for producing a LiTaO 3 single crystal, was heat-treated at 910 ° C. for 16 hours in a nitrogen gas atmosphere (Reference A), and in the atmosphere for comparison. When the spectral characteristics of what was heat-treated at 910 ° C for 16 hours (Material B) were examined, the results shown in Fig. 1 for absorbance (vertical axis) and wavelength (horizontal axis) were obtained, and at wavelengths of 400 nm or more. Is both A and B
It was confirmed that the absorption at 400 nm was smaller than that at 400 nm, but the absorption of A was smaller than that of B in the measurement wavelength region, and the absorption was remarkably small particularly near 400 nm.
【００１０】また、本発明はこの光透過性のすぐれたLi
TaO3単結晶の製造方法に関するものであり、これは前記
したように引上げたLiTaO3単結晶を還元性または不活性
ガス雰囲気中において 700℃以上で２時間加熱処理する
ことを特徴とするものであるが、この引上げ法によるLi
TaO3単結晶の製造は公知のイリジウム製るつぼ中にリチ
ウムタンタレートの焼結体を装入し、高周波加熱炉でこ
れを溶融し、種子結晶を用いてLiTaO3単結晶を引上げれ
ばよく、この育成雰囲気は酸素含有雰囲気とすることが
よいが、酸素濃度が 0.2％未満では結晶がねじれて育成
が困難となるし、５％以上とすると黄色の着色が強くな
るので、 0.8〜 2.0容量％とすることがよい。Further, the present invention is based on this excellent light-transmitting Li.
The present invention relates to a method for producing a TaO 3 single crystal, which is characterized in that the pulled LiTaO 3 single crystal as described above is heat-treated at 700 ° C. or higher for 2 hours in a reducing or inert gas atmosphere. There is Li by this pulling method
TaO 3 single crystal can be produced by charging a lithium tantalate sintered body into a known iridium crucible, melting it in a high frequency heating furnace, and pulling up the LiTaO 3 single crystal using a seed crystal. This growth atmosphere is preferably an oxygen-containing atmosphere. However, if the oxygen concentration is less than 0.2%, the crystals will be twisted and it will be difficult to grow, and if it is 5% or more, yellow coloring will be strong, so 0.8-2.0% by volume. It is good to say
【００１１】また、この育成後のLiTaO3単結晶について
は、これを水素、窒素などの還元性ガスまたは、アルゴ
ンガスなどの不活性ガス雰囲気下において加熱処理する
のであるが、この温度については 700℃未満では効果が
見られないので 700℃以上とする必要があるが、 1,600
℃以上とするとこの結晶からＬｉが蒸発するのでこれは
700〜 1,600℃の範囲とすることがよく、この加熱時間
については２時間未満では十分な効果が見られないの
で、２時間以上とする必要があるが、不必要に長くする
必要がないことから、好ましくは２〜20時間の範囲とす
ることがよい。The LiTaO 3 single crystal after the growth is heat-treated in a reducing gas such as hydrogen or nitrogen or in an inert gas atmosphere such as argon gas. The effect is not seen below ℃, so it is necessary to set it to 700 ℃ or higher.
If the temperature is above ℃, Li will evaporate from this crystal.
It is preferable to set the temperature in the range of 700 to 1,600 ° C. Regarding this heating time, if the heating time is less than 2 hours, sufficient effect cannot be seen. And preferably in the range of 2 to 20 hours.
【００１２】なお、このように加熱処理されたLiTaO3単
結晶は着色もなく、光透過性のすぐれたものとなるの
で、波長変換素子、光変調素子などのように光を通過さ
せて使用する素子用として好適なものになるという有利
性が与えられる。Since the LiTaO 3 single crystal thus heat-treated is not colored and has excellent light transmittance, it can be used as a wavelength converting element, a light modulating element or the like that allows light to pass therethrough. The advantage is given that it is suitable for devices.
【００１３】[0013]
【実施例】つぎに本発明の実施例、比較例をあげる。 実施例 直径 150mmφ、高さ 150mm、厚さ２mmのイリジウム製る
つぼにLiTaO3の焼結体10kgを装入し、高周波加熱炉でこ
れを融解させたのち、LiTaO3種結晶を接触させ、酸素ガ
スを 0.8容量％含んだ窒素ガス雰囲気下でLiTaO3単結晶
を育成させたのち、このLiTaO3単結晶を窒素ガス雰囲気
中において 700℃〜 910℃で２時間〜16時間加熱処理し
てこのものの波長λ≧400nm における光吸収係数を測定
したところ、表１に示したとおりの結果が得られたの
で、このものは光透過性のすぐれたものであることが確
認された。EXAMPLES Next, examples and comparative examples of the present invention will be described. Example 10 kg of a sintered body of LiTaO 3 was charged into an iridium crucible having a diameter of 150 mmφ, a height of 150 mm, and a thickness of 2 mm, and this was melted in a high-frequency heating furnace, and then LiTaO 3 seed crystal was brought into contact with oxygen gas. After growing a LiTaO 3 single crystal in a nitrogen gas atmosphere containing 0.8% by volume of nitrogen, this LiTaO 3 single crystal was heat-treated in a nitrogen gas atmosphere at 700 ° C to 910 ° C for 2 hours to 16 hours, When the light absorption coefficient at λ ≧ 400 nm was measured, the results shown in Table 1 were obtained, and it was confirmed that this product has excellent light transmittance.
【００１４】比較例 比較のために、実施例における熱処理条件を変更し、窒
素ガス雰囲気において700℃で１時間（比較例１）、 64
0℃で10時間（比較例２）としたところ、表１に示した
ように比較例１のものは光吸収係数が0.11cm-1、比較例
２のものは0.15cm-1となり、さらにこれを大気中におい
て 700℃で２時間としたもの（比較例３）はその光吸収
係数が0.17cm-1とさらにわるくなり、これらはいずれも
光透過性のわるいものとなった。Comparative Example For comparison, the heat treatment conditions in the examples were changed, and 700 ° C. in a nitrogen gas atmosphere for 1 hour (Comparative Example 1).
When the temperature was set to 0 ° C. for 10 hours (Comparative Example 2), as shown in Table 1, the light absorption coefficient of Comparative Example 1 was 0.11 cm −1 , and that of Comparative Example 2 was 0.15 cm −1 . When the temperature was 700 ° C. for 2 hours in the atmosphere (Comparative Example 3), the light absorption coefficient was 0.17 cm −1, which was even worse, and all of them had poor light transmittance.
【００１５】[0015]
【表１】 [Table 1]
【００１６】[0016]
【発明の効果】本発明は光用LiTaO3単結晶およびその製
造方法に関するものであるが、前記したようにこのLiTa
O3単結晶は波長λ≧400nm における光吸収係数が0.08cm
-1以下であることを特徴とするものであり、この製造方
法は引上げたLiTaO3単結晶を還元性または不活性ガス雰
囲気中において、 700℃以上で２時間以上加熱処理する
ことを特徴とするものであるが、この製造方法で作られ
たLiTaO3単結晶は波長λ≧400nm における光吸収係数が
0.08cm-1以下のものとなるし、このものは着色がなく、
光透過性のすぐれたものとなるのでこのものは波長変換
素子、光変換素子など、光を透過させて使用する素子用
として好適なものになるという有利性が与えられる。The present invention relates to a light-use LiTaO 3 single crystal and a method for producing the same.
O 3 single crystal has a light absorption coefficient of 0.08 cm at wavelength λ ≧ 400 nm
-1 or less, and this manufacturing method is characterized in that the pulled LiTaO 3 single crystal is heat-treated at 700 ° C. or more for 2 hours or more in a reducing or inert gas atmosphere. However, the LiTaO 3 single crystal produced by this manufacturing method has an optical absorption coefficient at wavelength λ ≧ 400 nm.
It will be less than 0.08 cm -1 , and this one has no coloring,
Since it has excellent light transmittance, it has an advantage that it is suitable for a wavelength conversion element, a light conversion element or the like which is used for transmitting light.
【図１】本発明の製造方法で作られたLiTaO3単結晶
（Ａ）と大気中での熱処理で作られたLiTaO3単結晶
（Ｂ）の吸光度と波長との相関図（吸光度の波長依存
性）を示したものである。FIG. 1 is a correlation diagram between the absorbance and the wavelength of the LiTaO 3 single crystal (A) produced by the production method of the present invention and the LiTaO 3 single crystal (B) produced by heat treatment in the air (wavelength dependence of the absorbance Sex).
Claims (2)
cm-1以下であることを特徴とするLiTaO3単結晶。1. The light absorption coefficient at a wavelength λ ≧ 400 nm is 0.08.
A LiTaO 3 single crystal characterized by being cm -1 or less.
活性ガス雰囲気中において、 700℃以上で２時間以上加
熱処理することを特徴とする光用LiTaO3単結晶の製造方
法。Wherein during the pulling was LiTaO 3 single crystal a reducing or inert gas atmosphere, a method of manufacturing an optical for LiTaO 3 single crystal, characterized in that the heat treatment for 2 hours or more at 700 ° C. or higher.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10189693A JP3724509B2 (en) | 1993-04-05 | 1993-04-05 | LiTaO3 single crystal for light and manufacturing method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10189693A JP3724509B2 (en) | 1993-04-05 | 1993-04-05 | LiTaO3 single crystal for light and manufacturing method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06293598A true JPH06293598A (en) | 1994-10-21 |
| JP3724509B2 JP3724509B2 (en) | 2005-12-07 |
Family
ID=14312688
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10189693A Expired - Fee Related JP3724509B2 (en) | 1993-04-05 | 1993-04-05 | LiTaO3 single crystal for light and manufacturing method thereof |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3724509B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100496526B1 (en) * | 2002-09-25 | 2005-06-22 | 일진디스플레이(주) | Method of producing lithium tantalate substrate for surface acoustic wave element |
-
1993
- 1993-04-05 JP JP10189693A patent/JP3724509B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100496526B1 (en) * | 2002-09-25 | 2005-06-22 | 일진디스플레이(주) | Method of producing lithium tantalate substrate for surface acoustic wave element |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3724509B2 (en) | 2005-12-07 |
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