JP6308487B2 - Stress luminescent material manufactured by stress luminescent material manufacturing method and stress luminescent material manufacturing method - Google Patents

Description

  The present invention relates to a method for producing a stress-stimulated luminescent material that emits light due to deformation caused by applying a mechanical external force.

  Conventionally, a phenomenon in which visible light is emitted near room temperature when a substance is given an external stimulus is well known as a so-called fluorescence phenomenon.

  A substance that generates such a fluorescent phenomenon, that is, a phosphor, is used as an illumination lamp such as a fluorescent lamp or a display such as a cathode ray tube (CRT) so-called cathode ray tube.

  External stimuli that cause this fluorescent phenomenon are usually given by ultraviolet rays, electron beams, X-rays, radiation, electric fields, chemical reactions, etc., but they can be deformed by applying stimuli such as mechanical external forces. A material that emits intense light has not been known for a long time.

  Therefore, as a result of intensive studies at the research institution to which the present inventor belongs, a novel light-emitting material that has not been known so far that emits light due to deformation caused by a mechanical external force has been proposed (for example, patent literature) 1).

  Such luminescent materials are later referred to as stress luminescent materials, and are now applied as new measurement technologies such as non-destructive inspection technology for maintaining existing civil engineering structures and visualization technology for stress distribution of structural members. There is a lot of research.

JP 2001-049251 A

  However, it is difficult to say that the conventional stress-stimulated luminescent material can always obtain sufficient luminescence for a minute strain of, for example, less than 1000 μst.

  This invention is made | formed in view of such a situation, Comprising: Compared with the conventional stress luminescent material, this invention provides the manufacturing method of the stress luminescent material which shows favorable light emission also with respect to a micro distortion.

In order to solve the above-described conventional problems, in the method for producing a stress-stimulated luminescent material according to the present invention, (1) a machine comprising an aluminate having a non-stoichiometric composition in which a luminescent center element is dispersed in a base material. A method for producing a stress-stimulated luminescent material that emits light by dynamic energy
A solution in which a salt of aluminum and an alkaline earth metal element and a salt of a luminescent center element constituting the matrix material are dissolved in a solvent, and an aluminum, an alkaline earth metal element, and a luminescent center element are ionized in the same solvent ( However, except for those containing organic acids.) And the solvent of the solution obtained in the ionization solution preparation step are evaporated with stirring without boiling, and dried on the surface. Evaporating and drying step to obtain a dry powder, and heating the dried powder obtained in the evaporating and drying step to 700 to 900 ° C. in an oxidizing atmosphere to obtain an oxide of aluminum and an alkaline earth metal element An oxidation step for obtaining a mixed powder of the oxide of the light emitting center element and an oxide of the luminescent center element, a sintering aid is added to the mixed powder obtained in the oxidation step, and the temperature is higher than that in the oxidation step. Firing for a predetermined time in a reducing atmosphere, An average grain in which the position of the maximum value of the main peak in the temperature range above room temperature of the glow curve obtained by thermoluminescence measurement at a heating rate of 60 K / min is less than 140 ° C, and multiple crystal grains are connected in the plane direction. And a firing step in which the obtained powder having a substantially flat shape with a diameter of 10 μm or more is used as a stress luminescent material.

The method for producing a stress-stimulated luminescent material according to the present invention is also characterized by the following points.
(2) The base material is composed of aluminum oxide and alkaline earth metal oxides, or One, an alkaline earth metal-deficient with deficient composition ratio of alkaline earth metal ions in the M _x Al ₂ O _{3 + x} , M _x QAl ₁₀ O _{16 + x} , M _x1 Q _x2 Al ₂ O _{3 + x1 + x2} or M _x1 Q _x2 LAl ₁₀ O _{16 + x1 + x2} [M in the formula , Q and L are Mg, Ca, Sr or Ba as the metal elements, respectively, x is a number satisfying 0.8 ≦ x ≦ 0.99, and x1 and x2 are 0.8 ≦ (x1 + x2) ≦ 0.99] The main component is the compound represented.
(3) The salt dissolved in the solvent in the ionization solution preparation step is nitrate, and the solvent is water.
(4) The luminescent center element is at least one selected from scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. Be.

The stress- stimulated luminescent material according to the present invention is a stress- stimulated luminescent material made of aluminate having a non-stoichiometric composition in which a luminescent center element is dispersed in a base material, and emits light by mechanical energy, The base material is composed of an aluminum oxide and an alkaline earth metal oxide, and is an alkaline earth metal deficient type in which the composition ratio of alkaline earth metal ions therein is deficient, and has the formula M _x Al ₂ O _{3 + x} , M _x QAl ₁₀ O _{16 + x} , M _x1 Q _x2 Al ₂ O _{3 + x1 + x2} or M _x1 Q _x2 LAl ₁₀ O _{16 + x1 + x2} [where M, Q and L are Each of which is Mg, Ca, Sr or Ba as the metal element, x is a number satisfying 0.8 ≦ x ≦ 0.99, x1 and x2 are numbers satisfying 0.8 ≦ (x1 + x2) ≦ 0.99] And the luminescent center element is scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, summary A temperature range above room temperature of a glow curve obtained by thermoluminescence measurement, which is at least one selected from sodium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium and does not contain an organic acid The peak position at is less than 140 ° C., and has a particle size of 10 μm or more and a substantially tabular grain shape .

  According to the method for producing a stress-stimulated luminescent material according to the present invention, it is possible to provide a method for producing a stress-stimulated luminescent material that exhibits good light emission even with a minute strain as compared with a conventional stress-stimulated luminescent material. Further, according to the present invention, it is possible to provide a stress-stimulated luminescent material that exhibits good light emission even with a minute strain as compared with a conventional stress-stimulated luminescent material.

It is explanatory drawing which showed the electron microscopic image of the stress luminescent material manufactured with the conventional manufacturing method, and the microstress luminescent material manufactured with the manufacturing method of the stress luminescent material which concerns on this embodiment. It is the figure which showed the emitted light intensity with respect to the micro distortion | strain of a micro stress luminescent material. It is the figure which showed the X-ray-diffraction pattern of the microstress luminescent material and the stress luminescent material for a comparison. It is the figure which showed the X-ray-diffraction pattern of the microstress luminescent material and the stress luminescent material for a comparison. It is the figure which showed the thermoluminescence measurement result. It is the figure which showed the emitted light intensity with respect to the micro distortion | strain of the micro stress luminescent material at the time of changing the amount of strontium.

  The present invention is a method for producing a stress-stimulated luminescent material, which is composed of an aluminate having a non-stoichiometric composition in which a luminescent center element is dispersed in a matrix material and emits light by mechanical energy, and constitutes the matrix material Preparation of an ionized solution in which a salt of aluminum and alkaline earth metal element and a salt of luminescent center element are dissolved in a solvent, and a solution in which the aluminum, alkaline earth metal element and luminescent center element are ionized is prepared in the same solvent A step of evaporating the solvent of the solution obtained in the ionization solution preparation step to obtain a dry powder, and heating the dry powder obtained in the step of evaporating and drying in an oxidizing atmosphere. In addition, an oxidation process for obtaining a mixed powder of an oxide of aluminum, an oxide of an alkaline earth metal element, and an oxide of a luminescent center element, and a sintering aid to the mixed powder obtained in the oxidation process. Add agent And a firing step in which the obtained powder is fired for a predetermined time in a reducing atmosphere at a temperature higher than that of the oxidation step, and the obtained powder is used as a stress light-emitting material. Is.

  A stress-stimulated luminescent material (hereinafter also referred to as a micro-stress luminescent material) manufactured by the method for manufacturing a stress-stimulated luminescent material according to the present embodiment has a trap level caused by lattice defects in the base material when excited by light. When electrons and holes (carriers) are captured and stress is applied to the base material, the captured carriers are released and recombined to emit light.

  For the base material having such lattice defects, at least one kind of aluminate having a non-stoichiometric composition is used. Here, the non-stoichiometric composition is a composition having a chemical composition formula that deviates from the stoichiometric chemical composition formula.

Such aluminates have a non-stoichiometric composition, it is composed of an alkaline earth metal oxide and aluminum oxide, One or was deficient in the composition ratio of alkaline earth metal ions in the Alkaline earth metal deficient, formula M _x Al ₂ O _{3 + x} , M _x QAl ₁₀ O _{16 + x} , M _x1 Q _x2 Al ₂ O _{3 + x1 + x2} or M _x1 Q _x2 LAl ₁₀ O _{16 + x1 + x2} [wherein M, Q and L are Mg, Ca, Sr or Ba as the metal elements, respectively, x is 0.8 ≦ x ≦ 0.99, and x1 and x2 are 0.8 ≦ (x1 + x2) And a main component of those represented by ≦ 0.99.

  Further, the luminescent center element used for the production of the stress luminescent material is, for example, scandium (Sc), yttrium (Y), or an element belonging to a lanthanoid, that is, lanthanum (La), cerium (Ce), praseodymium (Pr), Neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), Ytterbium (Yb), lutetium (Lu) and transition metal elements, i.e., titanium (Ti), zirconium (Zr), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co ), Nickel (Ni), copper (Cu), zinc (Zn), niobium (Nb), molybdenum (Mo), tantalum (Ta), tungsten (W), and the like.

The luminescent center element can be added in an amount sufficient to replenish the alkaline earth metal deficient in the composition ratio of the base material. For example, when the base material is represented by M _x Al ₂ O _{3 + x} , the stress luminescent material to which the luminescent center element is added is M _x Al ₂ O _{3 + x} : R _y (where R is the luminescent center element). Yes, it can be expressed as y ≦ (1-x)).

  These luminescent center elements may be added singly or in combination of two or more according to the lattice structure of the base material, the desired emission color, and the like.

  And as a characteristic point in the manufacturing method of the stress luminescent material which concerns on this embodiment, the point which performs an ionization solution preparation process, an evaporation drying process, an oxidation process, and a baking process can be mentioned.

  The ionization solution preparation process is performed by adding an aluminum salt, an alkaline earth metal element salt, and a luminescent center element salt to a solvent to dissolve the aluminum, alkaline earth metal element, and luminescent center element. Is a step of preparing an ionized solution (hereinafter also referred to as an ionized solution).

Here, the solvent used to prepare the ionization solution can dissolve the salt of aluminum, the salt of alkaline earth metal element, the salt of the luminescent center element, and when these elements are dissolved, The solvent is not particularly limited as long as it can be ionized. For example, water (H ₂ O) can be used.

  Further, when water is used as the solvent, it is preferable that the aluminum salt, the alkaline earth metal element salt, and the luminescent center element salt are all nitrates.

  By converting these salts into nitrates, a mixture of aluminum hydroxide, alkaline earth metal hydroxide, and luminescent center element hydroxide can be obtained in the evaporation and drying process described below. It is possible to improve the work efficiency by utilizing the high solubility of nitrate in water.

  Moreover, in dissolving each salt in a solvent, ultrasonic treatment can be used in combination. By using ultrasonic treatment in combination, each salt can be sufficiently dissolved in the solvent.

  Further, the amount of each salt dissolved in the solvent can be appropriately set to a known amount according to the desired base material and the composition ratio of the luminescent center element.

  The ionized solution thus obtained is then subjected to an evaporation / drying step in which the solvent of the solution is evaporated to obtain a dry powder.

  Specifically, the ionized solution is accommodated in a container such as an evaporating dish, and the solvent is evaporated by heating or decompression, and dried on the surface (for example, on the surface of the surface such as the bottom or wall of the container). Solidify.

  Next, the dry powder obtained in the evaporating and drying step is heated in an oxidizing atmosphere, and a mixed powder of an oxide of aluminum, an oxide of an alkaline earth metal element, and an oxide of a luminescent center element An oxidation process is performed to obtain a body.

  In this oxidation step, the dry powder obtained in the evaporation / drying step is accommodated in a heat-resistant container such as a crucible and heated in the presence of air.

  In addition, although the heating performed in the oxidation step varies depending on the alkaline earth metal element and luminescent center element used, the temperature at which the dry powder obtained in the evaporation-drying step can be chemically changed to a state where it can exist stably at room temperature. For example, the temperature may be an oxide, and may be about 500 to 1200 ° C., preferably 600 to 1000 ° C., more preferably 700 to 900 ° C.

  Next, a mixed powder of an aluminum oxide, an alkaline earth metal element oxide, and a luminescent center element oxide obtained through the oxidation step is reduced in a reducing atmosphere at a temperature higher than that in the above oxidation step. A firing step of firing for a predetermined time is performed.

  In the main firing step, a sintering aid may be added to the mixed powder. The sintering aid can be appropriately selected according to the type of the alkaline earth metal element or the luminescent center element. For example, boric acid or the like can be used.

  Moreover, as a reducing atmosphere at the time of performing this baking process, it can be set as inert gas atmosphere, such as argon which contains about 1-10 volume% of hydrogen, for example.

Also, the heating temperature of the main baking step is the formula M _x Al ₂ O _{3 + x} , M _x QAl ₁₀ O _{16 + x} , M _x1 Q _x2 Al ₂ O _{3 + x1 + x2} or M _x1 Q _x2 LAl ₁₀ O _{16 + x1 + x2} [wherein M, Q and L are Mg, Ca, Sr or Ba as the metal elements, respectively, x is 0.8 ≦ x ≦ 0.99, and x1 and x2 are 0.8 ≦ (x1 + x2) ≦ 0.99 It is sufficient that the temperature is such that a polycrystal composed of the above can be formed, and is a temperature range from the pre-baking temperature to 1450 ° C., preferably 1200 to 1400 ° C., more preferably 1250 to 1350 ° C. Can do.

  The powder fired product thus obtained can be used as a stress-stimulated luminescent material that exhibits good luminescence response to a microstress of, for example, about 100 to 1000 μst, that is, a microstress luminescent material. .

  By the way, the reason is that the microstress luminescent material manufactured by the stress luminescent material manufacturing method according to the present embodiment exhibits better luminescence response than the stress luminescent material prepared by the conventional method. Details are not yet clear at the stage.

  However, the present inventor has made two hypotheses at present, and the hypotheses will be described below for understanding of the present invention. However, these hypotheses are assumed based on currently known data and experience, and are not necessarily accurate. Therefore, the present invention should not be limitedly interpreted based on the following hypothesis.

  First, the first hypothesis is that the light emission responsiveness varies depending on the difference in defect level for trapping carriers.

  Although this will be described later with reference to FIG. 5, since the microstress luminescent material has a shallower defect level than the stress luminescent material prepared by the conventional method, it is trapped even by microstrain. The recombination of existing carriers can be promoted efficiently, and a high emission intensity can be obtained.

  The second hypothesis is that different luminescence responsiveness is caused by the difference in the particle shape of each stress luminescent material.

  FIG. 1 is an explanatory view showing a scanning electron microscope image of a microstress luminescent material. FIG. 1 (a) shows an SEM image of a conventional stress luminescent material, and FIG. 1 (b) shows an SEM image of a microstress luminescent material.

  As can be seen from FIG. 1 (a), the shape of the stress-stimulated luminescent material obtained by the conventional manufacturing method is substantially spherical, whereas as shown in FIG. 1 (b), the micro-stress luminescent material is slightly flat. It has a shape that is easy to deform.

  Therefore, it is considered that the micro-stress luminescent material is easily deflected by receiving stress as compared with the conventional stress luminescent material having a substantially spherical shape, and can obtain high luminescence intensity.

Hereinafter, the manufacturing method of the stress-stimulated luminescent material according to this embodiment will be described more specifically. In the following description, the method for producing a stress-stimulated luminescent material according to the present embodiment is also referred to as “evaporation drying method”. Further, the micro-stress luminescent material in the following _{Sr x Al 2 O 3 + x} : is the Eu _y will be described as an example and should not be construed as limited to the composition of the present invention. However, the invention is not prevented from being limited to the composition when receiving a patent.

[Preparation of micro-stress luminescent material]
First, a microstress luminescent material was prepared as follows. That is, Sr (NO ₃ ) ₂ (manufactured by Kanto Chemical), Eu (NO ₃ ) ₂ · 6H ₂ O (manufactured by Kanto Chemical), and Al (NO ₃ ) ₃ · 9H ₂ 0 (manufactured by High Purity Chemical Laboratory) Were weighed so as to be 0.97: 0.03: 2 in molar ratio, dissolved sufficiently in distilled water, and subjected to ultrasonic treatment for 1 hour using an ultrasonic generator to obtain an ionized solution (ionized solution). Preparation step).

  Next, when the obtained ionized solution is poured into a predetermined volume of an evaporating dish and the solvent can be evaporated without boiling, for example, when water is used as the solvent, the magnetized solution is heated at 80 to 90 ° C. for 2 to 3 hours. It was placed on a tic stirrer and evaporated to dryness with stirring (evaporation to dryness step).

  Next, the obtained dry powder is placed in a crucible and heated in air at 800 ° C. for 1 hour using a muffle furnace manufactured by Yamato Science Co., Ltd. A mixed powder of strontium oxide as the oxide and europium oxide as the emission center element oxide was obtained (oxidation step).

Then, H ₃ BO ₃ (manufactured by Wako Pure Chemical Industries, Ltd.) with a molar ratio of 0.1 to 1.0% is mixed as a sintering aid with respect to the obtained mixed powder of oxide, and the mixture is placed in a crucible, and reduced atmosphere carbon. Using an electric furnace, firing was performed at 1350 ° C. for 4 hours in a reducing atmosphere of 5% H ₂ / Ar, and the obtained powder was used as a microstress luminescent material.

[Preparation of comparative stress luminescent material]
Next, in order to perform a comparative test with a microstress luminescent material, a comparative stress luminescent material was prepared by a method different from the method for manufacturing the stress luminescent material according to the present embodiment. Note that the method described below is a method widely used at the time of preparing a stress-stimulated luminescent material, and may be referred to as a “solid phase reaction method”.

Specifically, SrCO ₃ (manufactured by Kanto Chemical Co., Inc.), Eu ₂ O ₃ (manufactured by High Purity Chemical Research Laboratories), and α-Al ₂ O ₃ (manufactured by High Purity Chemical Research Laboratories) are each 0.97 in molar ratio. : 0.03: 2 was weighed so that the molar ratio of 0.1 to 1.0% of H ₃ BO ₃ (manufactured by Wako Pure Chemical Industries, Ltd.) was added and thoroughly mixed in ethanol using a ball mill.

Next, ethanol was sufficiently evaporated from this mixture, and the obtained powder was placed in a crucible, heated in air at 800 ° C. for 1 hour using a Yamato Scientific muffle furnace, and then reduced in atmosphere. Using a carbon electric furnace, firing was performed at 1350 ° C. for 4 hours in a reducing atmosphere of 5% H ₂ / Ar, and the obtained powder was used as a comparative stress luminescent material.

[Light emission comparison test]
Next, the difference in light emission intensity between the above-described microstress luminescent material and the comparative stress luminescent material under microstrain conditions was compared.

_{Specifically, Sr x Al 2 O 4:} Eu y thick film upon tensile test by an adhesive metal specimen material testing machine Sr _x Al ₂ O _4: the light emission from Eu _y thick film by the CCD camera It was measured. _{Sr x Al 2 O 4: Eu} y thick film, a mixture of a commercially available epoxy resin and the above-mentioned sample (small stress luminescent material or comparative stress luminescent material) was prepared by screen printing. The thicknesses of the Sr _x Al ₂ O ₄ : Eu _y thick films of both materials were adjusted to be about 30 μm. The produced Sr _x Al ₂ O ₄ : Eu _y thick film was cut to a size of 10 x 10 cm and a metal test piece (SUS631, length 200 x width 20 x thickness 0.2 cm) using a commercially available adhesive Bonded to the center of the surface. The strain was measured with a uniaxial strain gauge adhered to the back surface of the metal test piece. The light emission measurement method for minute strains is Sr _x Al ₂ O when a tensile load is applied with a material tester so that the strain is about 1000 μst after excitation for 1 minute at a wavelength of 365 nm and standing for 1 minute. _4: the light emission from Eu _y thick measured by CCD camera. The result is shown in FIG. In FIG. 2, the microstress luminescent material is indicated by a solid line, and the comparative stress luminescent material is indicated by a broken line.

  As can be seen from FIG. 2, it can be seen that the microstress luminescent material exhibits high luminescence intensity even with a micro strain of 1000 μst or less, as compared with the comparative stress luminescent material.

  Also, it should be noted that conventional stress luminescent materials (comparative stress luminescent materials) emit little light at a stress of about 100 to 200 μst, whereas microstress luminescent materials are resistant to such small stresses. Even light emission can be shown.

  As described above, according to the method for manufacturing a stress-stimulated luminescent material according to the present embodiment, a stress-stimulated luminescent material that exhibits good light emission even with a minute strain is manufactured as compared with the conventional method for manufacturing a stress-stimulated luminescent material. be able to.

[Crystal structure comparison]
Next, the crystal structures of the microstress luminescent material and the comparative stress luminescent material were compared in order to investigate the light emission expression factor with respect to the microstrain of the microstress luminescent material.

FIG. 3 is a diagram showing the results of crystal structure analysis of the microstress luminescent material and the comparative stress luminescent material, and FIG. 4 is a diagram showing a diffraction pattern in which the range of 2θ = 26 to 34 ° is enlarged. . Note that the diffraction peaks of both stress luminescent materials are corrected by the diffraction peaks of the CeO ₂ standard sample mixed before the powder X-ray diffraction measurement.

As can be seen from FIG. 3, it can be seen that both the microstress luminescent material and the comparative stress luminescent material have a single phase of SrAl ₂ O ₄ formed thereon. Also, from the enlarged diffraction pattern shown in FIG. 4, the positions of the diffraction peaks of the micro-stress luminescent material indicated by the solid line and the comparative stress luminescent material indicated by the broken line coincided, and no peak shift was observed. It was shown that the comparative stress-stimulated luminescent material manufactured by the above method and the micro-stress luminescent material manufactured by the stress-luminescent material manufacturing method according to the present embodiment are the same in terms of crystal structure. That is, no structural difference was found from the comparison of X-ray diffraction patterns.

[Evaluation of defect levels by thermoluminescence measurement]
The light emission mechanism against the strain of stress-stimulated luminescent material is that when stress-stimulated luminescent material is excited by light such as ultraviolet light, the level caused by defects in the material is supplemented with electrons and holes (carriers). Are emitted by mechanical stimulation, and are considered to emit light upon recombination.

  In addition, when the temperature rises after excitation with ultraviolet light or the like, a phosphor having a defect emits light again by releasing electrons and holes captured in the trap level and radiative recombination at the emission center. (Thermoluminescence).

  That is, the peak position of the glow curve obtained by thermoluminescence measurement greatly affects the defect level.

  Therefore, both the above-described microstress luminescent material and comparative stress luminescent material were subjected to thermoluminescence measurement, and the defect levels of both stress luminescent materials were evaluated.

  When performing the thermoluminescence measurement, as a pretreatment, a minute or comparative stress luminescent material cooled to -190 ° C with liquid nitrogen is irradiated with 371 nm light for 5 minutes to sufficiently excite it, and then left in a dark place for 5 minutes. I put it.

  In the measurement, light emission at 514 nm was measured when the temperature of a minute or comparative stress light-emitting material was raised at 60 K / min. FIG. 5 shows the measurement results of the thermoluminescence measurement of the microstress luminescent material and the comparative stress luminescent material.

  As shown by the broken line in FIG. 5, according to the measurement result of the comparative stress luminescent material prepared by the conventional solid-phase reaction method, when attention is paid to the temperature above room temperature, a peak is obtained around 140 ° C. .

  On the other hand, according to the measurement result of the microstress luminescent material prepared by the method for manufacturing the stress luminescent material according to the present embodiment, as shown by the solid line in FIG. You can see that it was obtained.

  From this, it was considered that the microstress luminescent material had a shallower defect level than the comparative stress luminescent material, and exhibited high luminescence intensity against microstrain.

Moreover, from the evaluation results of the defect level by the thermoluminescence measurement and the comparison results of the above-mentioned crystal structure, the microstress luminescent material and the comparative stress luminescent material prepared by different methods are SrAl ₂ O regardless of the preparation method. It was confirmed that Eu ²⁺ was activated in SrAl ₂ O _{4 and} existed as _four single phases.

[Stress emission characteristics when the amount of alkaline earth metal element is changed]
Next, the stress luminescence characteristics when the amount of strontium in the base material of the above-described microstress luminescent material, that is, strontium aluminate was changed, were examined.

Specifically, a microstress luminescent material having a different amount of strontium, that is, Sr _x Al ₂ O ₄ : Eu _0.03 (x = 0.92 to 0.97) is prepared by the method of manufacturing a stress luminescent material according to the present embodiment, Each of the emission intensity was measured. The result is shown in FIG.

  As can be seen from FIG. 6, by decreasing the strontium amount from 0.97, the emission intensity with respect to a strain of 1000 μst or more increased, and the maximum value was shown when the strontium amount was 0.94.

  On the other hand, almost no change was observed in the luminescence intensity for microstrain of 1000 μst or less, particularly 500 μst or less, in any of the microstress luminescent materials.

  From this, it was shown that the light emission characteristic with respect to the micro strain of the micro stress light emitting material does not affect the strontium content in the strontium aluminate.

  As described above, according to the method for manufacturing a stress-stimulated luminescent material according to the present embodiment, light is emitted by mechanical energy made of an aluminate having a non-stoichiometric composition in which a luminescent center element is dispersed in a base material. A method for producing a stress-stimulated luminescent material, wherein a salt of aluminum and an alkaline earth metal element and a salt of a luminescent center element constituting the matrix material are dissolved in a solvent, and the aluminum and alkaline earth are dissolved in the same solvent. An ionization solution preparation step of preparing a solution in which a metal element and a luminescent center element are ionized; an evaporation and drying step of evaporating a solvent of the solution obtained in the ionization solution preparation step to obtain a dry powder; The dry powder obtained in the solid process is heated in an oxidizing atmosphere to obtain a mixed powder of an aluminum oxide, an alkaline earth metal element oxide, and an emission center element oxide. A sintering aid is added to the mixed powder obtained in the oxidation step and the oxidation step, and the resultant powder is fired for a predetermined time in a reducing atmosphere at a temperature higher than that in the oxidation step. Therefore, it is possible to provide a method for producing a stress-stimulated luminescent material that exhibits good light emission even with a minute strain as compared with a conventional stress-stimulated luminescent material.

  Finally, the description of each embodiment described above is an example of the present invention, and the present invention is not limited to the above-described embodiment. For this reason, it is a matter of course that various modifications can be made in accordance with the design and the like as long as they do not depart from the technical idea according to the present invention other than the embodiments described above.

Claims (4)

A method for producing a stress-stimulated luminescent material, which is composed of an aluminate having a non-stoichiometric composition in which a luminescent center element is dispersed in a base material and emits light by mechanical energy,
A solution in which a salt of aluminum and an alkaline earth metal element and a salt of a luminescent center element constituting the matrix material are dissolved in a solvent, and an aluminum, an alkaline earth metal element, and a luminescent center element are ionized in the same solvent ( However, an ionized solution preparation step for preparing an organic acid is excluded.)
Evaporating to dryness on the surface by evaporating the solvent of the solution obtained in the ionized solution preparation step while boiling without stirring, and evaporating to dryness on the surface;
The dry powder obtained in the evaporating and drying step is heated to 700 to 900 ° C. in an oxidizing atmosphere, and an oxide of aluminum, an oxide of an alkaline earth metal element, and an oxide of a luminescent center element An oxidation step to obtain a mixed powder of
By adding a sintering aid to the mixed powder obtained in the oxidation step, firing for a predetermined time in a reducing atmosphere at a temperature higher than that in the oxidation step, and measuring thermoluminescence at a heating rate of 60 K / min. The position of the maximum value of the main peak in the temperature range above the room temperature of the glow curve obtained is less than 140 ° C., and the obtained powder is a substantially flat plate having an average grain size of 10 μm or more in which a plurality of crystal grains are connected in the plane direction And a firing step using the body as a stress-stimulated luminescent material. The base material is composed of an aluminum oxide and an alkaline earth metal oxide, and is an alkaline earth metal deficient type in which the composition ratio of alkaline earth metal ions therein is deficient, and has the formula M _x Al ₂ O _{3 + x} , M _x QAl ₁₀ O _{16 + x} , M _x1 Q _x2 Al ₂ O _{3 + x1 + x2} or M _x1 Q _x2 LAl ₁₀ O _{16 + x1 + x2} [M, Q and L in the formula Are each Mg, Ca, Sr or Ba as the metal element, x is a number satisfying 0.8 ≦ x ≦ 0.99, x1 and x2 satisfying 0.8 ≦ (x1 + x2) ≦ 0.99] The method for producing a stress-stimulated luminescent material according to claim 1, comprising a main component.   The method for producing a stress-stimulated luminescent material according to claim 1 or 2, wherein the salt dissolved in the solvent in the ionization solution preparation step is nitrate, and the solvent is water.   The luminescent center element is at least one selected from scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. The method for producing a stress-stimulated luminescent material according to any one of claims 1 to 3.