JPH0692725A - Laser crystal and its production - Google Patents

Abstract

PURPOSE:To obtain a CaYTiAl perovskite type laser crystal emitting intense light in a specified wide wavelength region of visible light by growing a crystal from a melt contg. CaCO3, Y2O3, Al2O3 and Ti2O3 in a prescribed ratio in a reducing atmosphere. CONSTITUTION:Carbonate (CaCO3) or oxide (CaO) of a Ca ion is mixed with oxide (Y O) of a Y ion oxide (Al2O3) of an Al ion and oxide (Ti2O3) of Ti<3+> or oxide (TiO2) of Ti<4+> in 1:1:(1-X):X atomic ratio (0.001<=X<=0.05) of Ca:Y:Al: Ti. The mixture is melted in a reducing atmosphere under 10<-8> to 10<-18> atm partial pressure of oxygen and a crystal is grown from the resulting melt.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is useful as a light emitting material, and is also useful as a laser crystal or an optical amplifying device in the field of utilizing coherent light such as optical measurement, optical information processing, optical medical treatment, optical processing. The present invention relates to a laser crystal and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, Ti: A has been used as a crystal having a light emitting property or a laser property added with titanium.
l ₂ O ₃ (PF Molton, J. Opt. So
c. Am. B3,125 (1986)), Ti: YAl
O ₃ (T. Wegner et al, Appl. Phy
s. B49,275 (1989)), Ti: MgAl ₂
O ₄ (W. Strek et al, J. Appl. P
hys. 68, 15 (1990)) and the like are known.

However, among the above crystals, Ti: Al ₂
O ₃ and Ti: MgAl ₂ O ₄ have strong emission wavelength regions in the near infrared region of 700 to 1100 nm, and Ti: YA
lO is a ₃ visible to near infrared region of 550~850nm in, not strong emission is observed in the visible region of the blue-green-yellow of 400~600nm. Further, a crystal that uses CaYAlO ₄ as a host crystal and strongly emits light in a wide visible wavelength range from 400 to 600 nm has not been known so far.

[0004]

The present invention is particularly applicable to 40
A perovskite-type crystal containing titanium, which is a light-emitting material that strongly emits light in a wide visible wavelength range of 0 to 600 nm, which is blue to green to yellow, and which is useful as a laser material having a composition that has not been known as a material having laser characteristics. It is intended to be provided.

[0005]

In order to solve the above-mentioned problems, the present inventors have made various investigations, focusing on selecting titanium as a laser active ion and selecting a host crystal having a strong crystal field. As a result, the present invention has been completed.

That is, according to the present invention, Ca added with Ti ³⁺ ions or Ti ⁴⁺ ions as laser active ions.
The present invention relates to a YTiAl-based perovskite type crystal and a method for producing the same.

Next, the present invention will be described in more detail. In a preferred embodiment of the present invention, the amount of Ti ³⁺ or Ti ⁴⁺ used as the laser active ions satisfies the following conditions. That is, for Ti ³⁺ , the composition formula CaY
Ti _x Al _1-x O ₄ (x: 0.001 ≦ x ≦ 0.0
5), and for Ti ⁴⁺ , the composition formula CaYTi
_{3x Al 1-4x V x O 4 (} x: 0.001 ≦ x ≦ 0.
05, V: Al defects). As indicated by x in the above composition, 0.001 ≦ x ≦
If the amount is less than 0.001, the light emission intensity of the crystal is weak, and if it is more than 0.05, concentration quenching occurs, which is not preferable.

Next, the manufacturing method of the present invention will be described.
As a raw material used for obtaining the crystal of the present invention, an oxide or carbonate of each component constituting the crystal is used. For example, Ti
^{In the} composition formula CaYTiAl system crystal containing ³⁺ ,
Ca ion carbonate or oxide, Y ion oxide, A
An oxide of 1 ion and an oxide of Ti ion are used so that the produced crystal has a quantitative ratio as represented by the above composition formula, that is, Ca: Y: A in the atomic ratio of the grown crystal.
1: Ti = 1: 1: 1−x: x (0.001 ≦ x ≦ 0.
The mixture is mixed in an amount ratio of 05), and the mixture is melted and solidified in an atmosphere having an oxygen partial pressure of 10 ⁻⁸ to 10 ⁻¹⁸ atm to grow crystals.

The atmosphere for melting and solidification used here is, for example, hydrogen gas alone, a mixed gas of hydrogen and carbon dioxide or carbon monoxide, a mixed gas of carbon monoxide and carbon dioxide, and further these gases such as an inert gas. In an atmosphere in which a gas mixed with one or more of helium, argon, and nitrogen, or one or more gas of helium, argon, and nitrogen is used, and the oxygen partial pressure is kept at 10 ⁻⁸ to 10 ⁻¹⁸ atm Melt and solidify to grow crystals.

Here, the oxygen partial pressure is preferably within the above range, and when the oxygen partial pressure is less than 10 ⁻¹⁸ atm, Ti
^{The 3+} concentration is reduced to include Ti ²⁺ , and the emission intensity of the obtained crystal is lowered, or the concentration of the color center is increased to inhibit emission. Oxygen partial pressure is 10 ⁻⁸ a
When it is larger than tm, Ti ⁴⁺ is included and Ti
^{The 3+} concentration decreases, which causes the emission intensity of Ti ³⁺ itself to decrease. In addition, crystal defects increase and the optical quality of the crystal deteriorates.

The composition formula CaYTiAl containing Ti ⁴⁺ is also provided.
In the crystal, a carbonate or oxide of Ca ion, an oxide of Y ion, an oxide of Al ion, or an oxide of Ti ion is used, and these are used in an amount such that the produced crystal is represented by the above-mentioned composition formula. Ratio, that is, the atomic ratio of the grown crystal is Ca: Y: Ti: Al = 1: 1: 1-4x: 3x, and the mixture is mixed with helium, argon,
Under an atmosphere of one or more inert gases of nitrogen, or oxygen 0.1
Melt and solidify in an oxidizing atmosphere using one or more of helium, argon, and nitrogen gas containing at least vol%. Ti
^In the case of producing a crystal containing ⁴⁺ , if the crystal is grown in a reducing atmosphere, the obtained crystal contains Ti ³⁺ or Ti ^2+, which causes a decrease in the concentration of Ti ⁴⁺ .
In an atmosphere containing 0.1 vol% or more of oxygen, generation of color centers of crystals is small and high quality crystals can be obtained.

The melting temperature in the crystal production method of the present invention is about 18
00 to 1900 ° C, preferably 1820 to 1860 ° C
Then, a crystal is obtained by melting and solidifying by a pulling method, a floating zone method, a Bridgman method, a heat exchange method or the like.

[0013]

EXAMPLES Next, the present invention will be described in more detail with reference to Examples.

Example 1 CaCO ₃ , Y ₂ O ₃ , Al ₂ O ₃ and Ti ₂ O ₃ were added to the atomic ratio (Ca: Y: Al: Ti = 1: 1: 0.
98: 0.02), mixed, shaped, and sintered, put the sintered body in an iridium crucible, and perform high-frequency induction heating to 0.5 vo to contain Ti ³⁺ ions.
It was melted in a helium gas atmosphere containing 1% of hydrogen and pulled in the a-axis direction at a crystal rotation speed of 5 rpm and a pulling speed of 0.8 mm / h to obtain a single crystal having a diameter of 20 mm and a length of 50 mm.

The result of X-ray diffraction of the obtained crystal is shown in FIG. From the results of X-ray diffraction, the obtained crystal was a perovskite type single crystal phase and had a lattice constant of a = 6429A and c = 11.
It was 856A. The emission spectrum of this crystal when excited with light of 390 nm is shown in FIG. It had a peak at 510 nm and emitted light in the visible wavelength region of 420 to 620 nm. The emitted light was strongly polarized in the c-plane. The pulsed laser oscillation uses the second harmonic wave (390 nm) of the Cr: BeAl ₂ O ₄ laser as the pumping light source.
It was obtained around 15 nm.

Example 2 CaCO ₃ , Y ₂ O ₃ , Al ₂ O ₃ and TiO ₂ were grown at an atomic ratio of crystals (Ca: Y: Al: Ti = 1: 1: 0.9).
9: 0.01), and the sintered body of this mixture was put into an iridium crucible and heated and melted. The growth atmosphere is a mixture of helium gas and hydrogen prepared by mixing hydrogen and carbon dioxide gas at a volume ratio of 500: 1, and an oxygen partial pressure of 10 ^−8.
Atm. The pulling speed, the rotation speed, and the pulling direction were the same as in Example 1. As a result of X-ray diffraction, it was confirmed that the grown crystal had a single phase.

When the emission spectrum of this crystal was excited with excitation light of 391 nm, it was found to be 5 as with the crystal obtained in Example 1.
Strongly polarized in the c-plane with a peak at 07 nm 420 ~
Emission at 620 nm was confirmed.

Example 3 CaCO ₃ , Y ₂ O ₃ , Al ₂ O ₃ and Ti ₂ O ₃ were grown at an atomic ratio of crystals (Ca: Y: Al: Ti = 1: 1: 0.9).
The crystal was grown by a floating zone method at a growth rate of 2 mm / h in an argon gas atmosphere containing 1 vol% hydrogen, using a sintered body of the mixed material as a raw material. As a result of X-ray diffraction, the obtained crystal was confirmed to be a single phase. In addition, as a result of measuring the emission spectrum, the result was 420 to 620 nm as in Example 1.
The luminescence was seen at.

Example 4 CaCO ₃ , Y ₂ O ₃ , Al ₂ O ₃ , and TiO ₂ were grown at an atomic ratio (Ca: Y: Al: Ti = 1: 1: 0.9) of the grown crystal.
6: 0.03), mixed, molded, and sintered, and put the sintered body in an iridium crucible and high-frequency induction heating so as to contain Ti ⁴⁺ ions at 0.1 vo.
Melted in a helium gas atmosphere containing 1% oxygen, a crystal rotation speed was 10 rpm, and a pulling speed was 0.8 mm / h.
The single crystal having a diameter of 20 mm and a length of 38 mm was grown by pulling in the axial direction. It was confirmed from the result of X-ray diffraction that the obtained crystal was a single phase. The emission spectrum of this crystal when excited with light of 280 nm is shown in FIG. 450n
It had a peak near m and emitted light in the region of 400 to 630 nm. Further, it was observed that, unlike Examples 1, 2, and 3, it was non-polarized. The laser oscillation was obtained at around 455 nm using a XeCl laser as a pumping light source.

EXAMPLE 5 CaCO ₃ , Y ₂ O ₃ , Al ₂ O ₃ and TiO ₂ were added to the crystal atomic ratio (Ca: Y: Al: Ti = 1: 1: 0.94:
0.045) and using a sintered body of this mixture as a raw material, in an argon gas atmosphere containing 0.2 vol% oxygen, a growth rate of 1 mm / h, a-axis orientation, and a diameter of 5 mm by a floating zone method. A single crystal having a length of 15 mm was obtained. When the obtained crystal was excited with light of 280 nm in the same manner as in Example 4, broad emission of 400 to 620 nm was observed.

[0021]

EFFECT OF THE INVENTION The crystal of the present invention exhibits strong emission in a wide visible wavelength range and has laser characteristics, and is therefore useful as a laser medium.

[Brief description of drawings]

FIG. 1 is an X-ray diffraction diagram of the crystal obtained in Example 1 of the present invention.

FIG. 2 is a diagram showing an emission spectrum of the crystal obtained in Example 1 of the present invention.

FIG. 3 is a diagram showing an emission spectrum of the crystal obtained in Example 4 of the present invention.

Claims (8)

[Claims] 1. A CaYTiAl-based perovskite laser crystal containing Ti ³⁺ or Ti ⁴⁺ as laser active ions. 2. A composition formula CaYTi _x Al _1-x O ₄ (x: 0.00) containing Ti ³⁺ as laser active ions.
The laser crystal according to claim 1, represented by 1 ≦ x ≦ 0.05). 3. A composition formula CaYTi _{3 x} Al _1-4x V _x O ₄ (x: containing Ti ⁴⁺ as laser-active ions).
The laser crystal according to claim 1, represented by 0.001 ≦ x ≦ 0.05, V: Al defect). 4. A carbonate or oxide of Ca ions, an oxide of Y ions, an oxide of Al ions and Ti ³⁺ or Ti.
⁴⁺ oxide has a crystal of Ca: Y: Al: Ti (atomic ratio) = 1: 1: 1-x: x (x: 0.001 ≦ x ≦ 0.
05), and mixed so that the partial ratio of oxygen is 10 ^−8.
Composition formula CaYTi _x Al _1-x O characterized by melting and solidifying under an atmosphere of -10 ^-18 atm to grow crystals.
CaY represented by ₄ (x: 0.001 ≦ x ≦ 0.05)
A method for manufacturing a TiAl-based perovskite laser crystal. 5. A hydrogen gas alone, a mixed gas of hydrogen and carbon dioxide or carbon monoxide, a mixed gas of carbon monoxide and carbon dioxide, or these gases mixed with one or more of helium, argon and nitrogen. Gas, helium, or argon gas alone is used, and the oxygen partial pressure is 10 ⁻⁸ to 10
The production method according to claim 4, wherein the solidification is performed in an atmosphere kept at ^-18 atm. 6. A carbonate or oxide of Ca ion, an oxide of Y ion, an oxide of Al ion and Ti ³⁺ or Ti.
An oxide of ⁴⁺ Ti ions, the crystal of which is Ca: Y: Al: T
i (atomic ratio) = 1: 1: 1-4x: 3x (x: 0.00
1 ≦ x ≦ 0.05), and mixed and melted and solidified under an inert or oxidizing gas atmosphere to grow crystals. CaYTi _3x Al _1-4x V _x
O ₄ (x: 0.001 ≦ x ≦ 0.05, V: Al defect)
A method for producing a CaYTiAl-based perovskite-type laser crystal represented by: 7. As the inert gas, helium, argon,
The method according to claim 6, wherein one or more kinds of nitrogen are used. 8. The method according to claim 6, wherein a gas containing 0.1 vol% or more oxygen is used as the oxidizing gas.