JPS646160B2 - - Google Patents
Info
- Publication number
- JPS646160B2 JPS646160B2 JP55175807A JP17580780A JPS646160B2 JP S646160 B2 JPS646160 B2 JP S646160B2 JP 55175807 A JP55175807 A JP 55175807A JP 17580780 A JP17580780 A JP 17580780A JP S646160 B2 JPS646160 B2 JP S646160B2
- Authority
- JP
- Japan
- Prior art keywords
- oxygen
- crystal
- heat treatment
- acid compound
- tungstic acid
- 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.)
- Expired
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- 239000013078 crystal Substances 0.000 claims description 56
- 229910052760 oxygen Inorganic materials 0.000 claims description 31
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 29
- 239000001301 oxygen Substances 0.000 claims description 29
- 238000010438 heat treatment Methods 0.000 claims description 24
- 230000008018 melting Effects 0.000 claims description 18
- 238000002844 melting Methods 0.000 claims description 18
- 238000000034 method Methods 0.000 claims description 14
- -1 tungstic acid compound Chemical class 0.000 claims description 11
- 229910052725 zinc Inorganic materials 0.000 claims description 6
- 229910052793 cadmium Inorganic materials 0.000 claims description 5
- 229910052749 magnesium Inorganic materials 0.000 claims description 5
- 239000011261 inert gas Substances 0.000 claims description 2
- 239000000203 mixture Substances 0.000 claims 1
- 238000002834 transmittance Methods 0.000 description 12
- 238000009792 diffusion process Methods 0.000 description 10
- 238000010521 absorption reaction Methods 0.000 description 9
- PBYZMCDFOULPGH-UHFFFAOYSA-N tungstate Chemical compound [O-][W]([O-])(=O)=O PBYZMCDFOULPGH-UHFFFAOYSA-N 0.000 description 9
- 239000011701 zinc Substances 0.000 description 9
- 230000000694 effects Effects 0.000 description 5
- 239000000155 melt Substances 0.000 description 4
- 230000005855 radiation Effects 0.000 description 4
- 229910052721 tungsten Inorganic materials 0.000 description 4
- 239000012535 impurity Substances 0.000 description 3
- 239000010937 tungsten Substances 0.000 description 3
- 238000004040 coloring Methods 0.000 description 2
- 238000002591 computed tomography Methods 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 230000031700 light absorption Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 2
- 229910017672 MgWO4 Inorganic materials 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000004042 decolorization Methods 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- CMPGARWFYBADJI-UHFFFAOYSA-L tungstic acid Chemical class O[W](O)(=O)=O CMPGARWFYBADJI-UHFFFAOYSA-L 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G41/00—Compounds of tungsten
- C01G41/006—Compounds containing tungsten, with or without oxygen or hydrogen, and containing two or more other elements
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G41/00—Compounds of tungsten
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/10—Inorganic compounds or compositions
- C30B29/16—Oxides
- C30B29/22—Complex oxides
- C30B29/32—Titanates; Germanates; Molybdates; Tungstates
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B33/00—After-treatment of single crystals or homogeneous polycrystalline material with defined structure
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2002/00—Crystal-structural characteristics
- C01P2002/80—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70
- C01P2002/84—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70 by UV- or VIS- data
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/32—Thermal properties
- C01P2006/33—Phase transition temperatures
- C01P2006/34—Melting temperatures
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/60—Optical properties, e.g. expressed in CIELAB-values
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
- Measurement Of Radiation (AREA)
- Luminescent Compositions (AREA)
Description
【発明の詳細な説明】
本発明は、タングステン酸化合物（タングステ
ート：tungstate）単結晶の熱処理法に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for heat treating single crystals of tungstic acid compounds (tungstate).
Ｘ線CT（コンピユーテツド・トモグラフイー）
のスキヤナなどの放射線検出器に用いるシンチレ
ーターとして、従来、Bi4Ge3O12が使われてい
た。しかし、螢光強度、螢光の減衰時間などの点
で必らずしも満足できるものでなかつた。 X-ray CT (computed tomography)
Conventionally, Bi 4 Ge 3 O 12 has been used as a scintillator for radiation detectors such as scanners. However, it was not always satisfactory in terms of fluorescence intensity, fluorescence decay time, etc.
本発明者らは、すでに２価の金属元素Ｍ（Ｍ：
Mg、Zn、Cd）とタングステン（Ｗ）から成り、
MWO4で表わされるタングステン酸化合物およ
びこれらの混晶の単結晶を、放射線、紫外線を検
出するためのシンチレータ材料とすることについ
て特許を出願した。タングステート単結晶は通
常、チヨクラルスキー法（回転引上法）によつて
育成され、その後、所定のシンチレータの寸法に
切り出され使用される。シンチレータはその螢光
が強いことが要求される。シンチレータの螢光強
度は入射された放射線に対する発光効率と螢光に
対する結晶自体の吸収の大きさに影響され、発光
効率が大きく、吸収のないことが望しい。上記の
Mg、Zn、CdとＷより成るタングステートおよび
これらの混晶は室温において発光効率が高いシン
チレータ材料であり、螢光の強度分布は波長480
−490nｍにピークをもつ。タングステートの螢
光強度を高めるために、発光効率の低下と螢光の
吸収原因になる結晶中の不純物を除くが、全不純
物量を5ppm以下に下げた場合にも、結晶には薄
い茶褐色の着色が見られる。厚さ２mmのZnWO4
結晶板を例にすれば、波長480nｍにおける光の
透過率は60％に過ぎないし、光の透過率が低いこ
とは先に述べたように放射線によつて発生した螢
光の吸収とそれにともなう螢光強度の低下の原因
となる。 The present inventors have already discovered the divalent metal element M (M:
Consisting of Mg, Zn, Cd) and tungsten (W),
We have filed a patent application for using a tungstic acid compound represented by MWO 4 and a single crystal of a mixed crystal thereof as a scintillator material for detecting radiation and ultraviolet rays. A tungstate single crystal is usually grown by the Czyochralski method (rotational pulling method), and then cut into a predetermined size for use as a scintillator. The scintillator is required to have strong fluorescence. The fluorescence intensity of a scintillator is influenced by the luminous efficiency with respect to incident radiation and the magnitude of absorption of the fluorescent light by the crystal itself, and it is desirable that the scintillator has high luminous efficiency and no absorption. above
Tungstate consisting of Mg, Zn, Cd and W and their mixed crystals are scintillator materials with high luminous efficiency at room temperature, and the intensity distribution of fluorescence is at wavelength 480.
It has a peak at -490nm. In order to increase the fluorescence intensity of tungstate, impurities in the crystal that cause a decrease in luminous efficiency and absorption of fluorescence are removed, but even when the total amount of impurities is lowered to 5 ppm or less, the crystal has a light brown color. Coloring can be seen. 2mm thick ZnWO 4
Taking a crystal plate as an example, the light transmittance at a wavelength of 480 nm is only 60%, and as mentioned earlier, the low light transmittance is due to the absorption of fluorescence generated by radiation and the accompanying fluorescence. This causes a decrease in light intensity.
本発明は、より螢光強度の優れたシンチレータ
ーを得るための単結晶の処理法を提供することを
目的とする。本発明は、さらに上記の光の吸収の
原因を明らかにすることにより、螢光の吸収をな
くし、螢光強度を向上させることを目的とする。 An object of the present invention is to provide a method for treating a single crystal in order to obtain a scintillator with even better fluorescence intensity. The present invention further aims to eliminate the absorption of fluorescent light and improve the intensity of fluorescent light by clarifying the cause of the above-mentioned light absorption.
タングステートは酸素空格子点が発生し易い結
晶であり、タングステンが複数の原子価をとるた
め、結晶の着色は酸素空格子点−タングステンイ
オン、酸素空格子点−不純物元素イオンによつて
おこつているものと考えられた。これは光の吸収
が幅広い波長領域で生じること、ならびに一般に
酸化物の融液は酸素分解圧が高く、融液から生成
する結晶は酸素不足の状態になり易いことからも
言える。本発明では育成した結晶を高い酸素分圧
下で加熱することにより、結晶表面から酸素を結
晶中に拡散させ、育成時に発生した酸素空格子点
をなくした。それにより、螢光（最大発光波長
480nｍ）に対する吸収をなくし、螢光強度を向
上させた。 Tungstate is a crystal in which oxygen vacancies are likely to occur, and since tungsten has multiple valences, coloring of the crystal is done by oxygen vacancies - tungsten ions and oxygen vacancies - impurity element ions. It was thought that there was a This can be said because light absorption occurs in a wide wavelength range, and because oxide melts generally have a high oxygen decomposition pressure, crystals formed from the melt tend to be in an oxygen-deficient state. In the present invention, by heating the grown crystal under a high oxygen partial pressure, oxygen is diffused from the crystal surface into the crystal, thereby eliminating oxygen vacancies generated during growth. As a result, fluorescence (maximum emission wavelength)
480nm) and improved fluorescence intensity.
すなわち、本発明の熱処理法は、一般式
MWO4（ここにＭはMg、ZnおよびCdからなる群
から選ばれた少なくとも一種の元素を表わす）で
表わされるタングステン酸化合物の単結晶を、酸
素を有する雰囲気において融点未満でかつ融点よ
り200℃低い温度以上の範囲の温度で加熱するこ
とを特徴とする。 That is, the heat treatment method of the present invention is based on the general formula
A single crystal of a tungstic acid compound represented by MWO 4 (herein M represents at least one element selected from the group consisting of Mg, Zn, and Cd) is grown at a temperature below the melting point and 200°C above the melting point in an oxygen-containing atmosphere. It is characterized by heating at a temperature in a range above a low temperature.
加熱温度は、融点直下に近づくほど、酸素の拡
散が速く、実用上好ましい。しかしながら、融点
よりわずかに低い温度で加熱すると結晶の表面が
荒れるので、融点より30℃低い温度以下で加熱す
ることがより好ましい。また融点より200℃低い
温度よりさらに低い温度では効果はほとんどみら
れない。それ故、融点より30℃低い温度と、200
℃低い温度の間で加熱することがより好ましい。 The closer the heating temperature is to just below the melting point, the faster oxygen will diffuse, which is preferable for practical purposes. However, since heating at a temperature slightly lower than the melting point will roughen the surface of the crystal, it is more preferable to heat at a temperature 30° C. lower than the melting point. Further, almost no effect is seen at temperatures lower than 200°C below the melting point. Therefore, a temperature of 30 °C below the melting point and a temperature of 200
It is more preferable to heat between temperatures as low as 0.degree.
加熱する雰囲気は、酸素を含む雰囲気であるこ
とが必要である。還元性雰囲気中で加熱すると化
合物が還元され、分解する。それ故、不活性ガス
と酸素との混合雰囲気、とくに酸素10容量％以上
含む雰囲気中で加熱することが好ましい。酸素
100％の雰囲気であつてさしつかえない。 The atmosphere to be heated needs to be an atmosphere containing oxygen. When heated in a reducing atmosphere, the compound is reduced and decomposed. Therefore, it is preferable to heat in a mixed atmosphere of an inert gas and oxygen, particularly in an atmosphere containing 10% by volume or more of oxygen. oxygen
The atmosphere is 100% perfect.
以下本発明を実施例を用いて説明する。 The present invention will be explained below using examples.
実施例 １
まずタングステン酸亜鉛（ZnWO4）の例を説
明する。ZnWO4の融点は1220±５℃（J.C.Brice
によれば1190℃）であり、チヨクラルスキー法に
よる単結晶育成は白金るつぼを用いて行つた。融
液の分解・蒸発を防止するために、育成雰囲気は
酸素を用いた。高純度原料を用いて育成した単結
晶はわずかに茶褐色を呈し、その紫外および可視
領域での光に対する透過率曲線は第１図のＡであ
る。試料の厚さは２mmである。透過率曲線から明
らかなように幅の広い吸収があり、最大発光波長
480nｍにおける透過率は60％である。この結晶
を空気中で1100℃、30h加熱すると結晶表面から
酸素が結晶中に拡散し、結晶は茶褐色が薄黄色に
変色する。結晶表面から２つの色の境界までの深
さ、すなわち酸素の拡散距離には方向性がある。
1100℃、30hの条件下では、ａ軸〔100〕、ｂ軸
〔010〕方向では2.4〜2.7mm、Ｃ軸〔001〕方向で
は3.2mmである。この拡散距離の異方性はタング
ステート（単斜晶）の結晶構造の異方性に基づく
ものである。褐色がなくなつた結晶の透過率曲線
は第１図のＢで示した。熱処理によつて波長340
〜420nｍには新しく吸収が現われるが、ZnWO4
の最大発光波長480nｍにおける透過率は72％に
なる。屈折率の高い（ｎ＝2.14）ZnWO4結晶の
表面反射を補正すれば、この透過率はほぼ吸収が
ないことを示している。Example 1 First, an example of zinc tungstate (ZnWO 4 ) will be explained. The melting point of ZnWO 4 is 1220±5℃ (JCBrice
(1190℃), and single crystal growth by the Czyochralski method was performed using a platinum crucible. In order to prevent decomposition and evaporation of the melt, oxygen was used as the growth atmosphere. The single crystal grown using high-purity raw materials exhibits a slightly brownish color, and its transmittance curve for light in the ultraviolet and visible regions is shown in A in FIG. The thickness of the sample is 2 mm. As is clear from the transmittance curve, there is broad absorption, and the maximum emission wavelength
The transmittance at 480 nm is 60%. When this crystal is heated in air at 1100°C for 30 hours, oxygen diffuses into the crystal from the surface of the crystal, and the crystal changes color from brown to light yellow. The depth from the crystal surface to the boundary between the two colors, that is, the diffusion distance of oxygen, has a directionality.
Under the conditions of 1100°C and 30 hours, the thickness is 2.4 to 2.7 mm in the a-axis [100] and b-axis [010] directions, and 3.2 mm in the C-axis [001] direction. This anisotropy of the diffusion distance is based on the anisotropy of the tungstate (monoclinic) crystal structure. The transmittance curve of the crystal that has lost its brown color is shown as B in FIG. Wavelength 340 by heat treatment
New absorption appears at ~420 nm, but ZnWO 4
The transmittance at the maximum emission wavelength of 480 nm is 72%. If the surface reflection of the ZnWO 4 crystal with a high refractive index (n=2.14) is corrected, this transmittance indicates almost no absorption.
このようにして結晶の色を除去することによ
り、螢光の吸収が小さくなり、螢光強度は７％向
上した。 By removing the color of the crystals in this way, the absorption of fluorescence was reduced and the fluorescence intensity was increased by 7%.
なお螢光強度は以下のようにして測定した。放
射性同位元素 241Amからのγ線（エネルギ
60keV）を結晶に照射し、発生した螢光を光電子
増倍管によつて電気パルスに変換する。この電気
パルスの高さを波高分析器によつて、もつとも計
測数の多いパルス高（ピークチヤンネル値）を螢
光強度とした。以下、CdWO4、（Zn、Mg）WO4
の結晶の螢光強度も同様の方法で行つた。 Note that the fluorescence intensity was measured as follows. Gamma rays (energy
60keV) is irradiated onto the crystal, and the generated fluorescence is converted into electrical pulses using a photomultiplier tube. The height of this electric pulse was determined by a pulse height analyzer, and the pulse height (peak channel value), which was measured most often, was determined as the fluorescence intensity. Below, CdWO4 , (Zn, Mg) WO4
The fluorescence intensity of the crystal was also measured in the same manner.
熱処理条件について調べた結果、ZnWO4中の
酸素の拡散係数は1180℃で1.4×10-10m2／ｓ、
1140℃で1.2×10-10m2／ｓである。拡散係数の温
度依存性から求めた活性化エネルギは4.0×
10-19Jであつた。温度は融点直下に近づくほど、
酸素の拡散が速く、実用上望しい。 As a result of investigating the heat treatment conditions, the diffusion coefficient of oxygen in ZnWO 4 was 1.4×10 -10 m 2 /s at 1180℃,
It is 1.2×10 -10 m 2 /s at 1140°C. The activation energy calculated from the temperature dependence of the diffusion coefficient is 4.0×
It was 10 -19 J. As the temperature approaches just below the melting point,
Oxygen diffusion is fast, which is desirable for practical purposes.
一方、1060℃の場合、30h加熱を行つても拡散
層の厚さは1.7mmと薄く、1000℃以下は実用上不
適である。 On the other hand, in the case of 1060°C, the thickness of the diffusion layer is as thin as 1.7 mm even after heating for 30 hours, and a temperature of 1000°C or less is not practical.
熱処理雰囲気の影響について調べた結果N2中
で加熱した場合には脱色は見られない。一方、
N2＋10容量％O2雰囲気では空気中と同じ効果が
見られた。O2中では言うまでもない。しかし、
N2＋10容量％O2以上の酸素分圧では拡散距離へ
の酸素分圧の影響は見い出せなかつた。 As a result of investigating the influence of heat treatment atmosphere, no decolorization was observed when heated in N2 . on the other hand,
The same effect as in air was observed in an N 2 + 10% O 2 atmosphere. Needless to say in O2 . but,
No effect of oxygen partial pressure on the diffusion distance was found for N 2 + 10% O 2 by volume or higher oxygen partial pressure.
以上、ZnWO4単結晶の熱処理条件は1020℃〜
1190℃の温度範囲で10容量％以上の酸素雰囲気で
ある。 Above, the heat treatment conditions for ZnWO 4 single crystal are 1020℃~
The temperature range is 1190℃ and the oxygen atmosphere is 10% by volume or more.
実施例 ２
タングステン酸カドミウム（CdWO4）単結晶
の熱処理について説明する。CdWO4の融点は
1325℃でZnWO4より100℃高いが、チヨクラルス
キー法によつてZnWO4と同様に単結晶を育成し
た。育成したCdWO4単結晶は黄色を呈する。こ
れをZnWO4と同様に10容量％以上の酸素分圧下
で加熱したところ、黄色が薄くなつた。酸素が結
晶表面から拡散する拡散係数は1240℃で1.0×
10-10m2／ｓであり、ZnWO4とほぼ同じであつ
た。そして螢光強度は５％向上した。CdWO4の
場合にも1000℃ではほとんど拡散が観察されなか
つた。CdWO4の場合も融点よりも200℃低い温度
よりさらに低温では効果が少ないと言える。Example 2 Heat treatment of cadmium tungstate (CdWO 4 ) single crystal will be explained. The melting point of CdWO4 is
Although the temperature was 1325°C, which was 100°C higher than that of ZnWO 4 , single crystals were grown in the same manner as ZnWO 4 by the Czyochralski method. The grown CdWO 4 single crystal exhibits a yellow color. When this was heated under an oxygen partial pressure of 10% by volume or more like ZnWO 4 , the yellow color became lighter. The diffusion coefficient for oxygen to diffuse from the crystal surface is 1.0× at 1240℃
10 -10 m 2 /s, which was almost the same as ZnWO 4 . The fluorescence intensity was improved by 5%. In the case of CdWO 4 as well, almost no diffusion was observed at 1000°C. In the case of CdWO 4 as well, it can be said that it is less effective at temperatures lower than 200°C below the melting point.
実施例 ３
MgWO4単結晶は融液から直接できないが、
（Zn・Mg）WO4の混晶単結晶は育成することが
できる。ZnWO4とMgWO4の系において、
MgWO4を１％、５％、10％（各容量％）添加し
た混晶をチヨクラルスキー法によつて育成した。
結晶の育成速度（引上速度は３mm／ｈであつた。
各育成結晶の螢光強度はZnWO4とほぼ同じであ
つた。これらの単結晶はZnWO4とほとんど同じ
色および透過率曲線を示す。融点は10重量％
MsWO4を含むものでZnWO4より約20℃高く、熱
処理条件としては1040℃以上が望しい。拡散係数
は1180℃で1.5×10-10m2／ｓでZnWO4と同じであ
つた。熱処理前に比較して混晶の螢光強度は７％
向上した。Example 3 Although MgWO 4 single crystal cannot be produced directly from the melt,
Mixed single crystals of (Zn/Mg) WO4 can be grown. In the system of ZnWO4 and MgWO4 ,
Mixed crystals containing 1%, 5%, and 10% (volume %) of MgWO 4 were grown by the Czyochralski method.
Crystal growth rate (pulling rate was 3 mm/h).
The fluorescence intensity of each grown crystal was almost the same as that of ZnWO 4 . These single crystals show almost the same color and transmittance curves as ZnWO4 . Melting point is 10% by weight
It contains MsWO 4 and is about 20°C higher than ZnWO 4 , and the heat treatment conditions are preferably 1040°C or higher. The diffusion coefficient was 1.5×10 −10 m 2 /s at 1180° C., which was the same as ZnWO 4 . Fluorescence intensity of mixed crystal is 7% compared to before heat treatment
Improved.
以上、本発明ではZnWO4、CdWO4および
（Zn；Mg）WO4単結晶を1000℃以上望ましくは
融点とそれより200℃低い温度の範囲の温度、高
い酸素分圧下で加熱することにより、螢光強度が
５〜７％向上した。実施例ではZnWO4とCdWO4
および（Zn・Mg）WO4の３種類の単結晶につい
て説明したが、ZnWO4、MgWO4、CdWO4は同
一結晶構造をもち、似た性質であるため、これら
の混晶に対しても熱処理の効果が見られることは
言うまでもない。 As described above, in the present invention, ZnWO 4 , CdWO 4 and (Zn;Mg)WO 4 single crystals are heated at a temperature of 1000°C or higher, preferably between the melting point and 200°C lower than the melting point, and under high oxygen partial pressure. Light intensity improved by 5-7%. In the example ZnWO4 and CdWO4
We have explained three types of single crystals, (Zn・Mg)WO 4 and (Zn・Mg)WO 4 , but since ZnWO 4 , MgWO 4 , and CdWO 4 have the same crystal structure and similar properties, heat treatment is also required for these mixed crystals. Needless to say, the effects of this can be seen.
さらに、本発明の熱処理は結晶中の残留ひずみ
を除く効果をも有しており、へき開性が強く割れ
易いタングステート単結晶の加工を容易にするも
のである。 Furthermore, the heat treatment of the present invention has the effect of removing residual strain in the crystal, and facilitates the processing of tungstate single crystals, which have strong cleavability and are easily broken.
第１図はZnWO4単結晶の熱処理前後の光の透
過率曲線を示す図である。曲線Ａは熱処理前を示
し、曲線Ｂは熱処理後の脱色した部分の透過率を
示す。
FIG. 1 is a diagram showing light transmittance curves of ZnWO 4 single crystal before and after heat treatment. Curve A shows the transmittance before heat treatment, and curve B shows the transmittance of the bleached part after heat treatment.
Claims (1)
Cdからなる群から選ばれた少なくとも一種の元
素を表わす）で表わされるタングステン酸化合物
の単結晶を、酸素を有する雰囲気において、融点
未満でかつ融点より200℃低い温度以上の範囲の
温度で加熱することを特徴とするタングステン酸
化合物単結晶の熱処理法。 ２ 上記酸素を有する雰囲気が、酸素を10容量％
以上100容量％以下の範囲の量で含む酸素と不活
性ガスとの混合系の雰囲気である特許請求の範囲
第１項記載のタングステン酸化合物単結晶の熱処
理法。 ３ 上記温度が、融点より30℃低い温度以下、融
点より200℃低い温度以上の範囲の温度である特
許請求の範囲第１項又は第２項記載のタングステ
ン酸化合物単結晶の熱処理法。 ４ 上記タングステン酸化合物がZnWO4である
特許請求の範囲第１項から第３項までのいずれか
に記載のタングステン酸化合物単結晶の熱処理
法。 ５ 上記タングステン酸化合物がCdWO4である
特許請求の範囲第１項から第３項までのいずれか
に記載のタングステン酸化合物単結晶の熱処理
法。 ６ 上記タングステン酸化合物が（Zn・Mg）
WO4である特許請求の範囲第１項から第３項ま
でのいずれかに記載のタングステン酸化合物単結
晶の熱処理法。[Claims] 1. General formula MWO 4 (herein, M represents Mg, Zn and
(representing at least one element selected from the group consisting of Cd) is heated in an oxygen-containing atmosphere at a temperature below the melting point and at least 200°C lower than the melting point. A heat treatment method for a tungstic acid compound single crystal, characterized by: 2 The above oxygen-containing atmosphere contains 10% by volume of oxygen.
The method for heat treatment of a tungstic acid compound single crystal according to claim 1, wherein the atmosphere is a mixture of oxygen and an inert gas in an amount ranging from 100% by volume to 100%. 3. The method for heat treatment of a tungstic acid compound single crystal according to claim 1 or 2, wherein the temperature is in the range of 30° C. lower than the melting point or higher and 200° C. lower than the melting point or higher. 4. The method for heat treatment of a tungstic acid compound single crystal according to any one of claims 1 to 3, wherein the tungstic acid compound is ZnWO 4 . 5. The method for heat treatment of a tungstic acid compound single crystal according to any one of claims 1 to 3, wherein the tungstic acid compound is CdWO 4 . 6 The above tungstic acid compound is (Zn・Mg)
A method for heat treatment of a tungstic acid compound single crystal according to any one of claims 1 to 3, which is WO 4 .
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP55175807A JPS57100999A (en) | 1980-12-15 | 1980-12-15 | Heat treatment of single crystal of tungstic acid compound |
| DE3148988A DE3148988C2 (en) | 1980-12-15 | 1981-12-10 | Process for the heat treatment of a tungstate single crystal |
| GB8137633A GB2089777B (en) | 1980-12-15 | 1981-12-14 | Process for heat-treating single crystal of tungstate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP55175807A JPS57100999A (en) | 1980-12-15 | 1980-12-15 | Heat treatment of single crystal of tungstic acid compound |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS57100999A JPS57100999A (en) | 1982-06-23 |
| JPS646160B2 true JPS646160B2 (en) | 1989-02-02 |
Family
ID=16002574
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP55175807A Granted JPS57100999A (en) | 1980-12-15 | 1980-12-15 | Heat treatment of single crystal of tungstic acid compound |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS57100999A (en) |
| DE (1) | DE3148988C2 (en) |
| GB (1) | GB2089777B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7749323B2 (en) | 2006-05-30 | 2010-07-06 | Hitachi Chemical Company, Ltd. | Single crystal for scintillator and method for manufacturing same |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4560877A (en) * | 1982-12-29 | 1985-12-24 | General Electric Company | Solid state detector module |
| JP4037362B2 (en) * | 2001-07-12 | 2008-01-23 | 古河機械金属株式会社 | Method for producing tungstate single crystal |
| JP2003041244A (en) * | 2001-07-25 | 2003-02-13 | Furukawa Co Ltd | Scintillator |
| JP2005263515A (en) * | 2004-03-16 | 2005-09-29 | Mitsui Mining & Smelting Co Ltd | Zinc tungstate single crystal and method for producing the same |
| JP2005272274A (en) * | 2004-03-26 | 2005-10-06 | Mitsui Mining & Smelting Co Ltd | Zinc tungstate single crystal and method for producing the same |
| JP2005263621A (en) * | 2004-02-17 | 2005-09-29 | Mitsui Mining & Smelting Co Ltd | Zinc tungstate single crystal and method for producing the same |
| JP2005343753A (en) * | 2004-06-03 | 2005-12-15 | Mitsui Mining & Smelting Co Ltd | Zinc tungstate single crystal and method for producing the same |
| WO2005078171A1 (en) * | 2004-02-17 | 2005-08-25 | Mitsui Mining & Smelting Co., Ltd. | Zinc tungstenenate single crystal and method for preparation thereof |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2240301A1 (en) * | 1972-08-16 | 1974-02-28 | Siemens Ag | PROCESS FOR MANUFACTURING SEMICONDUCTOR SINGLE CRYSTAL BARS WITH SPECIFIC RESISTANCE DROPPING DOWN TO THE CENTER OF THE BAR |
| DE2550154A1 (en) * | 1975-11-07 | 1977-05-12 | Alusuisse | THERMAL TREATMENT OF SUBSTRATE PLATES |
-
1980
- 1980-12-15 JP JP55175807A patent/JPS57100999A/en active Granted
-
1981
- 1981-12-10 DE DE3148988A patent/DE3148988C2/en not_active Expired
- 1981-12-14 GB GB8137633A patent/GB2089777B/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7749323B2 (en) | 2006-05-30 | 2010-07-06 | Hitachi Chemical Company, Ltd. | Single crystal for scintillator and method for manufacturing same |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3148988A1 (en) | 1982-06-24 |
| DE3148988C2 (en) | 1986-01-02 |
| JPS57100999A (en) | 1982-06-23 |
| GB2089777A (en) | 1982-06-30 |
| GB2089777B (en) | 1984-06-13 |
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