JPH11263970A - Luminous material, its production and light emission using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a luminous material which is of the kind entirely different from a conventionally known one and is capable of emitting light by deformation caused by a mechanical external force such as a frictional force, shearing force or an impact force. SOLUTION: This luminous material is produced by adding an oxide of a rare earth metal or a transition metal having an unstable 3d, 4d, 5d or 4f electron shell and capable of causing the radiation transition in the electron shell in an amount of 0.02-0.5 mol.% expressed in terms of metal atoms to an oxide or a compound oxide of at least one metal belonging to the groups 2A, 3A, 4A and 3B of the periodic table, slowly increasing the temperature thereof to 900-1,100 deg.C in an inert atmosphere and then baking the resultant mixture at 1,200-1,500 deg.C in a reducing atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel light-emitting material which emits light by deformation caused by the application of a mechanical external force, a novel light-emitting material which has not been known so far, a method for producing the same, and a light-emitting method using the same. .

[0002]

2. Description of the Related Art Heretofore, a phenomenon in which a substance emits light in the vicinity of the visible region at a low temperature due to an external stimulus is well known as a so-called fluorescent phenomenon. A substance that causes such a fluorescent phenomenon, that is, a fluorescent substance, is used for an illumination light such as a fluorescent lamp or a CRT (Cathode Ray).
Tube) is used as a display such as a so-called cathode ray tube. The external stimulus that causes this fluorescence phenomenon is given by ultraviolet rays, electron beams, X-rays, radiation, electric fields, chemical reactions, etc., but until now, it has been deformed by applying a mechanical external force to emit light. The material to do was unknown.

[0003]

SUMMARY OF THE INVENTION The present invention relates to a novel and totally different kind of novel light source which emits light by deformation caused by mechanical external forces such as frictional force, shear force and impact force. The purpose of the present invention is to provide a light emitting material.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to develop a novel luminescent material which emits light by mechanical deformation. In addition, they have found that a substance containing a rare earth metal ion or a transition metal ion having specific properties as a central ion of a luminescence center has such performance, and based on this finding, have completed the present invention.

That is, the present invention provides a periodic table 2A, 3A,
In the host crystal of the oxide or composite oxide of at least one metal belonging to groups 4A and 3B, unstable 3d, 4d,
It has a 5d or 4f electron shell, and is made of a substance containing, as a central ion of a luminescence center, at least one metal ion selected from a rare earth metal ion and a transition metal ion capable of causing radiation transition in the electron shell. An object of the present invention is to provide a light-emitting material that emits light by mechanical deformation, and a light-emitting method characterized by applying a mechanical external force to the light-emitting material to cause deformation. In addition, according to the present invention, the luminescent material is unstable to 3d, 4d, 5d or 4f with respect to an oxide or composite oxide of at least one metal belonging to Groups 2A, 3A, 4A and 3B of the periodic table. An oxide of at least one metal selected from the group consisting of a rare earth metal and a transition metal capable of causing a radiative transition in the electron shell, having an electron shell in an amount of 0.02 to 0.5 mol in terms of metal atoms. % In an inert atmosphere and gradually heated to a temperature in the range of 900 to 1100 ° C., and then reduced to 1200 to 1500 in a reducing atmosphere.
It can be manufactured by firing at a temperature in the range of ° C.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The luminescent material of the present invention is a novel functional material which emits light by being deformed by applying a mechanical external force, and is a host crystal of a specific metal oxide or composite oxide. It is made of a substance containing a rare earth metal ion or a transition metal ion as the central ion of the luminescent center. In the present invention, an oxide of at least one metal selected from metals belonging to Groups 2A, 3A, 4A and 3B of the periodic table, particularly metals having an atomic weight in the range of 24 to 180, as a host crystal and as a raw material for production. Alternatively, a composite oxide is used.

Such metal oxides or composite oxides include MgO, SrO, CaO, ZrO ₂ , CeO ₂ ,
A metal oxide selected from HfO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , Cr ₂ O ₃ and Ti ₂ O ₃ or a composite oxide thereof is preferable. From a high point, spinel structure, fluorite structure, yttria structure,
Those having a crystal structure of corundum structure or β-alumina structure are preferred. As a metal oxide or composite oxide having such a crystal structure, MgAl ₂ O ₄ , SrAl ₂ O ₄ , C
aAl ₂ O ₄ , fluorite-structured ZrO ₂ , CeO ₂ , HfO
_2, Y ₂ O ₃ yttria structure, corundum structure Al ₂ O
₃ , SrM with Cr ₂ O ₃ , Ti ₂ O ₃ and β-alumina structure
Metal oxides or composite oxides selected from gAl ₁₀ O ₁₇ can be used. Particularly preferred are those having a spinel structure and a β-alumina structure.

A rare earth metal ion or a transition metal ion contained as a central ion of a luminescence center in a host crystal of such a metal oxide or a composite oxide is for dramatically improving the luminescence intensity. In the present invention, the rare earth metal ion or the transition metal ion has an unstable 3d, 4d, 5d or 4f electron shell, and an ion capable of causing a radiative transition in the electron shell is a host crystal. Introduced inside. Among them, particularly preferred are those having a first ionization energy of 8 eV or less, particularly 6 eV or less.

Among transition metal ions having an unstable 3d electron shell, preferred are V, Cr, Mn, Fe, Co,
Preferred among transition metal ions having an unstable 4d electron shell, such as Ni, Cu, Zn, etc., are Nb and Mo, and preferred among transition metal ions having an unstable 5d electron shell. , Ta, and W. On the other hand, among the rare earth metal ions having an unstable 4f electron shell, preferred are Ce,
Examples include Pr, Nd, Pm, Sm, Eu, Gd, Tb, and Dy. Preferred metals in the transition metal oxide and rare earth metal oxide used in the production method of the present invention are exactly the same as the metals in the above-mentioned preferred predetermined metal ions.

One or more of these rare earth metal ions and transition metal ions are appropriately selected according to the crystal structure of the parent metal oxide or composite oxide and the like. It can be introduced into the crystal. In the light-emitting material of the present invention, the emission intensity changes depending on the combination of the host crystal and the emission center. In particular, a metal oxide or complex oxide having a β-alumina structure or a spinel structure is used as the host crystal, Those having at least one kind of metal ion selected from metal ions as the emission center exhibit high emission intensity.

The luminescent material of the present invention can be efficiently produced by the following method. First, periodic table 2
A powder of an oxide or composite oxide of at least one metal belonging to Groups A, 3A, 4A and 3B
a powder of an oxide of at least one metal selected from the above-mentioned rare earth metals and transition metals having a d, 4d, 5d or 4f electron shell and capable of causing radiation transition in the electron shell, It is added at a ratio of 0.02 to 0.5 mol% in terms of atoms and mixed well. If the amount of the rare earth metal or transition metal oxide powder is outside the above range, sufficient luminous efficiency cannot be obtained.

Next, this mixed powder is placed in an inert atmosphere such as nitrogen gas or argon gas, or in a vacuum, for 90 hours.
The temperature is gradually raised to a temperature in the range of 0 to 1100 ° C. and calcined. Next, the calcined powder is formed into a desired shape under pressure, and is then placed in a reducing atmosphere such as hydrogen gas at 1200 to 1200 μm.
By firing at a temperature in the range of 1500 ° C. for about 30 to 300 minutes, a desired luminescent material can be obtained.

The luminous intensity of the luminescent material thus obtained is strongly dependent on the crystallinity, and the higher the crystallinity of the oxide, the higher the luminous intensity tends to be. Therefore, the emission intensity can be improved by improving the crystallinity. Further, in this light emitting material, light emission in various wavelength regions is possible by a combination of the base metal oxide and the central ion of the light emission center, and a change in the wavelength region can be confirmed with the naked eye.

The luminescent material of the present invention emits light by applying a mechanical external force, for example, a frictional force, a shearing force, an impact force, or the like, to cause deformation, that is, elastic deformation or plastic deformation. This light emission occurs when the crystal is deformed by a mechanical external force or when the crystal is restored by removing the mechanical external force. Generally, the emission intensity tends to increase as the applied mechanical external force increases. Therefore, by measuring the luminous intensity, the mechanical acting force applied to the luminescent material can be known. This makes it possible to detect the state of stress applied to the luminescent material without contact,
It can be expected to be applied in a wide range of fields.

[0015]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 High purity MgAl which is a typical oxide having a spinel structure
After sufficiently mixing each ratio of high-purity CeO ₂ powder with ₂ O ₄ powder, the mixture was calcined by gradually raising the temperature to 1000 ° C. over 60 minutes in a vacuum. At this stage, MgAl ₂ O ₄
Cerium ions serving as luminescence centers are generated therein. Next, the calcined powder was molded under pressure and fired at 1300 ° C. for 120 minutes in a reducing atmosphere (in a hydrogen gas atmosphere).
By this high-temperature firing, cerium ions are introduced into the crystal structure of MgAl ₂ O ₄ . For each luminescent material thus obtained, the luminescence intensity under the same excitation conditions was measured,
A comparison was made. FIG. 1 is a graph showing the relationship between the amount of cerium ions added and the emission intensity in semilogarithmic coordinates. The luminous intensity was measured by rubbing the surface of the luminescent material with a hemispherical stainless steel rod having a diameter of 1 mm under a load of 200 g and a speed of 4 m / min. As can be seen from FIG. 1, when the cerium ion addition amount is 0.05 mol%,
The light emission intensity is 220 cps, indicating the highest light emission intensity. This luminescence was observable with the naked eye and was white. In addition, MgAl ₂ to which cerium ions were not added
The emission intensity of O ₄ was about 40 cps.

Examples 2 to 5 In the same manner as in Example 1, 0.05 Al of Eu ions (Example 2), Mn ions (Example 3) and Cu ions (Example 4) were added to MgAl ₂ O _4. Mol% of a luminescent material, and 0.05 mol% of Eu ions and 0.0 of Tb ions.
A luminescent material containing 5 mol% (Example 5) was produced,
The emission intensity was measured. The results are shown in Table 1 together with Example 1 (with the addition of 0.05 mol% of Ce ions).

[0018]

[Table 1]

Table 1 shows that MgAl ₂ O ₄ to which Ce ions are added exhibits the highest emission intensity.

Example 6 In the same manner as in Example 1, a spinel oxide C
A light-emitting material in which 0.05 mol% of Ce ions was contained in aAl ₂ O ₄ was manufactured, and the light-emitting intensity was measured. As a result, the light-emitting intensity was 180 cps. The luminous intensity of the conventionally known oxide luminous body was 5 cps or less, and it was found that the luminous intensity was considerably higher than the conventional one.

Example 7 In the same manner as in Example 1, the oxide S having a spinel structure was used.
A light emitting material in which 0.05 mol% of Ce ions was added to rAl ₂ O ₄ was manufactured, and the light emission intensity was measured. As a result, the light emission intensity was 60 cps. The luminous intensity of the conventionally known oxide luminous body is 5 cps or less, which indicates that the luminous intensity is higher than that of the conventional one.

Examples 8 to 10 In the same manner as in Example 1, an oxide having a fluorite structure, Z
rO ₂ (Example 8), HfO ₂ (Example 9), CeO
_{2 In} Example 10, a luminescent material containing 0.05 mol% of Ce ions was manufactured, and the luminescence intensity was measured. Table 2 shows the results.

[0023]

[Table 2]

From Table 2, it can be seen that each of the luminescent materials has a higher luminous intensity than conventionally known luminescent materials.

Example 11 In the same manner as in Example 1, a luminescent material containing 0.05 mol% of Ce ions in Y ₂ O ₃ , which is a typical oxide having an yttria structure, was produced. As a result of the measurement, the light emission intensity was 30 cps, which was higher than that of a conventionally known light emitter.

Examples 12 to 14 In the same manner as in Example 1, oxides having a corundum structure of Al ₂ O ₃ (Example 12), Cr ₂ O ₃ (Example 13) and Ti ₂ O ₃ (Example 14), each Ce ion 0.0
A luminescent material containing 5 mol% was produced, and the luminescence intensity was measured. Table 3 shows the results.

[0027]

[Table 3]

From Table 3, it can be seen that each of the luminescent materials has a higher luminous intensity than conventionally known luminous bodies.

Example 15 In the same manner as in Example 1, a luminescent material was prepared by adding 0.5 mol% of Eu ions to SrMgAl ₁₀ O ₁₇ which is an oxide having a β-alumina structure, and the luminescence intensity was measured. did. Table 4 shows the results.

[0030]

[Table 4]

[0031]

The luminescent material of the present invention contains a rare-earth metal ion or a transition metal ion as a central ion of a luminescent center in a host crystal of a metal oxide having a specific crystal structure. It is a novel functional material that has not been known until now, which emits light when deformed by applying an external force. The luminescent material of the present invention can be expected to be widely applied to, for example, a new non-contact controller that changes a mechanical action into light, various control processes, and the like. In addition, this luminescent material has excellent stability at high temperatures, and can be expected to be applied at high temperatures.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between Ce ion addition amount and luminous intensity in a luminescent material obtained by adding Ce ion as a central ion of a luminescent center to MgAl ₂ O ₄ .

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI G01L 1/00 G01L 1/00 Z

Claims (12)

[Claims] An unstable 3d, 4d, 5d or 4f electron shell is present in a host crystal of an oxide or a composite oxide of at least one metal belonging to Groups 2A, 3A, 4A and 3B of the periodic table. A luminescent material that emits light by mechanical deformation of a substance containing, as a central ion of a luminescent center, at least one metal ion selected from a rare earth metal ion and a transition metal ion capable of causing a radiative transition in the electron shell. . 2. The base crystal is composed of MgO, SrO, CaO,
ZrO ₂ , CeO ₂ , HfO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , Cr ₂
O ₃ and the light emitting material according to claim 1, wherein a metal oxide or a composite oxide thereof selected from among Ti ₂ O _3. 3. The luminescent material according to claim 2, wherein the host crystal has a spinel structure, a fluorite structure, a yttria structure, a corundum structure or a β-alumina structure. 4. The center ion of the emission center is Ce, Pr, N
4. The luminescent material according to claim 1, wherein the luminescent material is a rare earth metal ion selected from d, Pm, Sm, Eu, Gd, Tb and Dy. 5. The center ions of the luminescence center are V, Cr, M
n, Fe, Co, Ni, Cu, Zn, Nb, Mo, Ta
And a transition metal ion selected from W and W.
5. The light emitting material according to any one of items 1 to 4. 6. An unstable 3d, 4d, 5d or 4f electron shell for an oxide or composite oxide of at least one metal belonging to Groups 2A, 3A, 4A and 3B of the periodic table;
An oxide of at least one metal selected from rare earth metals and transition metals capable of causing radiation transition in the electron shell is added at a ratio of 0.02 to 0.5 mol% in terms of metal atoms. After gradually increasing the temperature to a temperature in the range of 900 to 1100 ° C. in an inert atmosphere,
A method for producing a luminescent material which emits light by mechanical deformation, characterized by firing at a temperature in the range of ~ 1500C. 7. An oxide or composite oxide of at least one metal belonging to groups 2A, 3A, 4A and 3B of the periodic table,
MgO, SrO, CaO, ZrO ₂ , CeO ₂ , Hf
_{O 2, Y 2 O 3,} Al 2 O 3, Cr 2 O 3 and a manufacturing method of a light-emitting material according to claim 6, wherein a metal oxide or a composite oxide thereof selected from among Ti ₂ O _3. 8. The method according to claim 7, wherein the metal oxide or the composite oxide has a spinel structure, a fluorite structure, an yttria structure, a corundum structure, or a β-alumina structure. 9. The rare earth metal is Ce, Pr, Nd, P
The method for producing a luminescent material according to claim 6, 7 or 8, wherein the method is selected from m, Sm, Eu, Gd, Tb and Dy. 10. The transition metal is V, Cr, Mn, Fe,
The method for producing a luminescent material according to any one of claims 6 to 9, wherein the luminescent material is selected from Co, Ni, Cu, Zn, Nb, Mo, Ta and W. 11. An unstable 3d, 4d, 5d or 4f electron shell in a host crystal of an oxide or composite oxide of at least one metal belonging to Groups 2A, 3A, 4A and 3B of the periodic table. A mechanical external force is applied to a luminescent material made of a substance containing, as a central ion of a luminescent center, at least one metal ion selected from a rare earth metal ion and a transition metal ion capable of causing radiation transition in the electron shell. In addition, a light emitting method characterized by causing deformation. 12. The light emitting method according to claim 11, wherein the deformation is an elastic deformation or a plastic deformation.