WO2018070072A1 - Stress light-emitting material, stress light-emitter, and use of stress light-emitting material - Google Patents

Stress light-emitting material, stress light-emitter, and use of stress light-emitting material Download PDF

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WO2018070072A1
WO2018070072A1 PCT/JP2017/018824 JP2017018824W WO2018070072A1 WO 2018070072 A1 WO2018070072 A1 WO 2018070072A1 JP 2017018824 W JP2017018824 W JP 2017018824W WO 2018070072 A1 WO2018070072 A1 WO 2018070072A1
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stress
luminescent material
stimulated luminescent
nbo
light
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PCT/JP2017/018824
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French (fr)
Japanese (ja)
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徐超男
塗東
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国立研究開発法人産業技術総合研究所
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Priority to JP2018544680A priority Critical patent/JP7097072B2/en
Publication of WO2018070072A1 publication Critical patent/WO2018070072A1/en

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G33/00—Compounds of niobium
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/67—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing refractory metals
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general

Definitions

  • the present invention relates to the use of a stress luminescent material, a stress luminescent material, and a stress luminescent material.
  • stress-stimulated luminescent materials are known as materials that emit luminescence correlated to their energy by mechanical stimuli from the outside. Sensors, nondestructive inspection, visualization of stress distribution, stress sensing, and structural abnormalities ⁇ Various uses such as danger detection are expected.
  • stress-stimulated luminescent materials using a piezoelectric material as a base material have been studied in various ways because of their advantages of enabling various electronic control functions and the ability to perform multiple conversion of electricity, force, and light.
  • the stress-stimulated luminescent materials based on the piezoelectric material studied so far have weak piezoelectricity when the stress luminescence intensity is relatively high, and those that use a strong piezoelectric material as the base material. There is a tendency that the stress emission intensity is weak.
  • the conventional stress-stimulated luminescent material is composed of a mixed phase, and a single-phase stress-stimulated luminescent material is not known so far although it is a piezoelectric body.
  • the present invention has been made in view of such circumstances, and provides a single-phase stress luminescent material using a piezoelectric material as a base material, which can emit light with high sensitivity even with a minute force.
  • the present invention also provides a stress luminescent material obtained by dispersing a stress luminescent material in a predetermined matrix material, a use of the stress luminescent material, and a method of manufacturing the stress luminescent material.
  • a part of Li constituting the crystal of LiNbO 3 is at least one selected from rare earth metal ions and transition metal ions. It was decided to be replaced by metal ions.
  • the stress-stimulated luminescent material according to the present invention is also characterized by the following points.
  • (2) General formula Li x NbO 3 : M y (where M is at least one metal ion selected from a rare earth metal ion and a transition metal ion replacing a part of Li constituting the crystal of LiNbO 3 . And non-stoichiometric composition, x 1 ⁇ y, and 0.0001 ⁇ y ⁇ 0.2.
  • the metal ion is Pr 3+ .
  • the stress-stimulated luminescent material according to the present invention is characterized in that (6) the stress-stimulated luminescent material described in any one of (1) to (5) is dispersed in a predetermined matrix material.
  • the present invention is characterized by (7) the use of the stress-stimulated luminescent material according to any one of the above (1) to (5) for detecting a force of 1000 pN or less by luminescence.
  • the present invention is characterized in that (8) the stress-stimulated luminescent material described in any one of (1) to (5) above is used to detect minute strains of 100 ⁇ st or less by light emission.
  • the base material is LiNbO 3 which is obtained by mixing and firing a niobium compound, a lithium compound, and a compound of at least one metal selected from rare earth metals and transition metals.
  • the method for producing a stress-stimulated luminescent material is characterized in that the molar ratio of niobium atoms to lithium atoms is 1: 0.8 to 3.0.
  • a part of Li constituting the LiNbO 3 crystal is replaced with at least one metal ion selected from rare earth metal ions and transition metal ions. It is possible to provide a single-phase stress luminescent material using a piezoelectric material as a base material and capable of emitting light with high sensitivity even for a large force.
  • Li x NbO 3 M y (where M is at least one metal ion selected from a rare earth metal ion and a transition metal ion substituting for a part of Li constituting the crystal of LiNbO 3 )
  • M 1 ⁇ y and 0.0001 ⁇ y ⁇ 0.2
  • Li x NbO 3 M y (where M is at least one metal ion selected from a rare earth metal ion and a transition metal ion substituting for a part of Li constituting the crystal of LiNbO 3 )
  • M is at least one metal ion selected from a rare earth metal ion and a transition metal ion substituting for a part of Li constituting the crystal of LiNbO 3 .
  • the emission intensity can be improved more steadily.
  • the metal ion is Pr 3+ , light emission according to stress can be caused more steadily.
  • the stress-stimulated luminescent material according to the present invention since these stress-stimulated luminescent materials are dispersed in a predetermined matrix material, it is possible to provide a stress-stimulated luminescent material that emits light when subjected to stress.
  • a minute force of 1000 pN or less can be detected by light emission if the above-described stress light emitting material is used.
  • a micro strain of 100 ⁇ st or less can be detected by light emission.
  • LiNbO 3 is obtained by mixing and firing a niobium compound, a lithium compound, and a compound of at least one metal selected from rare earth metals and transition metals.
  • a single-phase stress luminescent material having a body as a base material can be manufactured.
  • the present invention provides a stress-stimulated luminescent material in which a part of Li constituting a crystal of LiNbO 3 is substituted with at least one metal ion selected from rare earth metal ions and transition metal ions.
  • a stress-stimulated luminescent material is a material that exhibits luminescence correlated with its energy by mechanical stimulation, and is expected to be applied in various fields.
  • the present inventor has developed various stress light emitters, and has also studied a stress light emitter using a piezoelectric material as a base material.
  • stress emission can be confirmed with famous piezoelectric materials such as PZT.
  • Ba 1-x Ca x TiO 3 Pr 3+ emitted light in response to stress, but this was due to the combined action of the piezoelectric phase and the electroluminescence phase, and stress emission in a single phase could not be realized. It was. That is, the results so far have shown that a material using a typical piezoelectric material as a base material does not exhibit good stress luminescence.
  • LiNbO 3 is a ferroelectric substance with a high Curie temperature, and has been attracting attention for a long time because of its piezoelectric characteristics, electro-optical characteristics, and nonlinear optical characteristics, and is currently widely used as an excellent electro / optical material. .
  • the inventors of the present invention have discovered for the first time that the function as a stress-stimulated luminescent material is expressed by doping Pr 3+ into LiNbO 3 through intensive studies, and have completed the present invention.
  • the present invention relates to a stress-stimulated luminescent material using as a base material LiNbO 3 doped with Pr 3+, which is the first material exhibiting both high piezoelectric characteristics and stress-stimulated luminescent characteristics.
  • the stress-stimulated luminescent material according to the present embodiment is characterized by being a single phase while being a base material having piezoelectricity.
  • the single phase means that a single type of crystal phase is completed from excitation to light emission regardless of other crystal phases, and the generated stress luminescent material does not contain an impurity phase. It does not necessarily mean that. That is, the crystalline phase characteristic of the stress-stimulated luminescent material according to the present embodiment, that is, a part of Li constituting the LiNbO 3 crystal is formed by at least one metal ion selected from rare earth metal ions and transition metal ions. If the substituted stress emission phase is included, the stress emission property is obtained regardless of the presence or absence of other impurity phases.
  • the stress-stimulated luminescent material for example, Sc (scandium), Y (yttrium), La (lanthanum), Ce (cerium), Pr (praseodymium), Nd (neodymium), Pm (promethium) , Sm (samarium), Eu (europium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Yb (ytterbium), Lu (lutetium) It can be understood that
  • transition metal ions can be interpreted as transition metal ions existing between Group 3 elements and Group 11 elements.
  • the metal ions used for substituting a part of Li constituting the LiNbO 3 crystal are particularly limited as long as they are the rare earth metal ions and transition metal ions described above. It is not a thing.
  • a stress-stimulated luminescent material it is possible to obtain a single-phase stress-stimulated luminescent material using a piezoelectric body as a base material, which can emit light with high sensitivity even with a minute stress.
  • y is less than 0.0001 because the emission intensity is significantly reduced.
  • y exceeds 0.2, the ratio of impurities increases, and the ratio of the LiNbO 3 crystal phase that emits stress light decreases, so that the stress light emission intensity decreases, which is not preferable.
  • the stress light-emitting material according to the present embodiment the general formula Li x NbO 3: having a non-stoichiometric composition represented by M y, x> a 1-y, with 0.0001 ⁇ y ⁇ 0.2 It is good to be.
  • x at this time may be 0.8 ⁇ x ⁇ 3.0.
  • the metal ion may be Pr 3+ .
  • the stress-stimulated luminescent material according to the present embodiment having such a configuration has extremely high stress responsiveness, for example, it can be used to detect a force of 1000 pN or less by luminescence.
  • it can be used to detect minute strains of 100 ⁇ st or less by light emission.
  • the stress-stimulated luminescent material according to this embodiment described above may be dispersed in a predetermined matrix material to form a stress-stimulated luminescent material.
  • a stress-stimulated luminescent material that emits light by applying stress can be easily obtained by dispersing and curing a powdered stress-stimulated luminescent material in the resin before curing, using a curable resin as a matrix material. Can be formed. Note that at least the matrix material that can transmit the excitation light for exciting the stress luminescent material mixed in the matrix material and the fluorescence emitted from the stress luminescent material is used.
  • the stress-stimulated luminescent material is not limited to a solid, and may be a liquid material having fluidity.
  • a paint containing the stress-stimulated luminescent material according to this embodiment is also included in the concept of the stress-stimulated luminescent material.
  • the method for producing a stress-stimulated luminescent material according to the present embodiment is based on LiNbO 3 obtained by mixing and firing a niobium compound, a lithium compound, and a compound of at least one metal selected from a rare earth metal and a transition metal.
  • the stress-luminescent material manufacturing method is characterized in that the molar ratio of niobium atoms to lithium atoms is 1: 0.8 to 3.0.
  • the niobium compound is not particularly limited as long as it is a compound capable of constructing a LiNbO 3 crystal through mixing and firing processes.
  • Nb 2 O 5 , NbCl 5 , NbF 5, etc. it can.
  • the lithium compound is not particularly limited as long as it is a compound capable of constructing a LiNbO 3 crystal.
  • it can be Li 2 CO 3 , LiNO 3 , LiCl, or the like.
  • the compound of at least one metal selected from rare earth metals and transition metals is not particularly limited, and an oxide of the same metal can be used.
  • Pr is selected as the metal
  • Pr 2 O 3 , PrCl 3 , Pr (NO 3 ) 3 and the like can be used.
  • These compounds can be mixed according to known synthesis methods regardless of whether they are dry or wet.
  • the solid phase synthesis method may be used.
  • the method for producing a stress-stimulated luminescent material according to this embodiment is characterized in that the molar ratio of niobium atoms to lithium atoms is 1: 0.8 to 3.0, more specifically 1: 0.95 to 2.4. It is done.
  • the ratio of lithium atoms When the ratio of lithium atoms is less than 0.8 with respect to the ratio of niobium atoms of 1, the luminous efficiency is remarkably lowered, which is not preferable. On the other hand, if the ratio of lithium atoms exceeds 3.0, a decrease in luminous efficiency appears remarkably, which is not preferable.
  • the molar ratio of niobium atoms to lithium atoms By setting the molar ratio of niobium atoms to lithium atoms to 1: 0.8 to 3.0, more preferably 1: 0.95 to 2.4, a stress-stimulated luminescent material that responds extremely efficiently to stress can be produced.
  • Samples were prepared by solid phase synthesis. Nb 2 O 5 as a niobium compound, Li 2 CO 3 as a lithium compound, Pr 2 O 3 as a compound of at least one metal selected from rare earth metals and transition metals, and Li x NbO 3 : Pr 3+ y x And weighed so that y had the target composition, and then mixed and ground in an agate mortar. x was adjusted within the range of 0.8 ⁇ x ⁇ 3.0, and y was adjusted within the range of 0.0001 ⁇ y ⁇ 0.2.
  • samples were prepared by firing them in an electric furnace.
  • the reaction precursor powder was formed into pellets with a hydraulic machine and fired. Firing was performed in a muffle furnace, the firing conditions were 1050 ° C. for 8 hours in the air, and the heating rate was 3 ° C./min.
  • the fired sample was pulverized in a mortar and subjected to various measurements as a powdered material of the stress-stimulated luminescent material according to this embodiment.
  • the formation of LiNbO 3 was confirmed at any doping amount. Further, in the sample in which the Pr 3+ doping amount was less than 2 mol%, as shown in the 0.5 mol% chart in FIG. 1, no significant peak derived from the impurity phase was confirmed. On the other hand, in the sample in which the Pr 3+ dope amount was 2 mol% to 10 mol%, as shown in the 10 mol% chart in FIG. 1, a peak considered to be derived from the impurity phase was observed. In addition, in the samples with a low dope amount of 0 mol% to 0.5 mol%, a slight orientation was observed in the crystal phase.
  • FIG. 2A shows the result of fluorescence spectroscopy measurement. But not doped with Pr 3+ as an emission center of the fluorescent can not be confirmed, when doped with Pr 3+, as shown in FIG. 2 (a), the emission peak was observed around 620 nm.
  • the fluorescent characteristics for Pr 3+ doping amount as shown in FIG.
  • the stress emission characteristics were evaluated.
  • the stress luminescence property was evaluated by a stress luminescence evaluation system by preparing a cylindrical resin pellet (diameter: 2.5 cm, height: 1.5 cm) by mixing a fired sample and a resin to obtain a stress luminescent material.
  • the measuring method applied the load of the perpendicular direction with respect to the resin pellet, and measured the emitted light intensity at that time with the photon sensor. The result is shown in FIG.
  • FIG. 3A shows a stress emission curve of each sample.
  • the sample not doped with Pr 3+ shows no light emission.
  • stress luminescence according to the increase in applied load was confirmed.
  • the stress emission intensity increased with an increase in the dope amount, and in the sample prepared this time, the one with 5 mol% showed the highest stress emission intensity.
  • the fluorescence intensity of the fluorescence intensity was lower in the sample added with 5 mol% than that in the sample added with 0.5 mol%, whereas it was 0.5 mol% in the stress emission intensity. It is interesting to note that the 5 mol% added sample has a higher emission intensity than the added sample.
  • the impurity phase other than LiNbO 3 is It was not confirmed, but it was confirmed that a single phase of LiNbO 3 (PDF No.01-085-2456) was formed.
  • a slight crystal phase of Li 3 NbO 4 was confirmed as an impurity phase.
  • the horizontal axis represents the value of x of Li x NbO 3 : Pr 3+ y (0.95 ⁇ x ⁇ 1.05), the left vertical axis represents the lattice constant a, and the right vertical axis represents the axial ratio c / a. Yes.
  • the difference in crystal structure due to the difference in the value of x became clear.
  • x values of 0.95 and 0.97 indicate relatively high values exceeding 5.152, and x values of 0.99 to 1.03, which are stoichiometric ratios, remain relatively low values below 5.151.
  • x values of 0.99 to 1.03 which are stoichiometric ratios
  • the stress luminescence characteristics were evaluated.
  • the previous [2. Similar to Li x NbO 3 : Pr 3+ y (x 1, 0 ⁇ y ⁇ 0.1)], the stress luminescence characteristics are a cylindrical resin pellet (diameter: 2.5 cm, high by mixing the fired sample and resin) The thickness was 1.5 cm) to obtain a stress luminescent material, which was evaluated by a stress luminescence evaluation system.
  • the measuring method applied the load of the perpendicular direction with respect to the resin pellet, and measured the emitted light intensity at that time with the photon sensor. The result is shown in FIG.
  • FIG. 5 (a) is a stress luminescence curve with a load of 0 to 1000N in each sample when the value of x is changed within the range of 0.95 ⁇ x ⁇ 1.00 for Li x NbO 3 : Pr 3+ 0.01 .
  • FIG. 5B is a graph showing the light emission intensity at a load of 1000 N in each sample when the value of x is changed within the range of 0.95 ⁇ x ⁇ 1.05 for Li x NbO 3 : Pr 3+ 0.01. It is.
  • the enhancement of the emission intensity is considered to be based on the difference in the crystal structure derived from the lithium amount x, and the lattice constant a is less than 5.151.
  • the stress-stimulated luminescent material containing Li x NbO 3 : Pr 3+ y having a crystal structure with an axial ratio c / a exceeding 2.6900 can be used as a stress-stimulated luminescent material having excellent stress responsiveness. .
  • the stress-stimulated luminescent material according to this embodiment exhibits an unprecedented ultra-high sensitivity, and when repeated strain is applied, the ultra-sensitive stress luminescence is repeated with good reproducibility. It was confirmed that In particular, even within the range of small strain (0 to 300 ⁇ st, especially 0 to 100 ⁇ st), the stress emission intensity of LiNbO 3 : Pr 3+ coating increases linearly with increasing strain, and LiNbO 3 : Pr It was confirmed that it is possible to obtain stress emission with small strain and high sensitivity using 3+ .
  • FIG. 7A shows changes with time in stress and luminescence
  • FIG. 7B shows a relationship between equivalent stress and linear proportion.
  • FIG. 7 (a) shows that the stress emission intensity increases with the load.
  • the stress luminescence characteristics were evaluated.
  • the previous [2. Similar to Li x NbO 3 : Pr 3+ y (x 1, 0 ⁇ y ⁇ 0.1)], the stress luminescence characteristics are a cylindrical resin pellet (diameter: 2.5 cm, high by mixing the fired sample and resin) The thickness was 1.5 cm) to obtain a stress luminescent material, which was evaluated by a stress luminescence evaluation system.
  • the measuring method applied the load of the perpendicular direction with respect to the resin pellet, and measured the emitted light intensity at that time with the photon sensor. The result is shown in FIG.
  • the emission intensity decreased to 1929.
  • the stress-stimulated luminescent material according to the present embodiment can obtain sufficient light emission according to the stress even in a state having an impurity phase. Also from this point, it can be seen that the impurity phase does not contribute to the stress luminescence and does not inhibit the stress luminescence to such an extent that it becomes impractical.
  • the stress-stimulated luminescent material according to the present embodiment emits light in response to extremely small stress or strain, and in particular, it exhibits light emission even for a minute strain of 100 ⁇ st or less. It can be said that it is characteristic.
  • Such a stress-stimulated luminescent material according to this embodiment can be applied to, for example, highly sensitive measurement of stress against minute strain.
  • the force that generates a strain of several tens of ⁇ st in a nanomachine or the like is a force of about 1 to 1000 pN (pN order force). If the material is arranged, the light emission material with the same stress can respond to a strain of several tens of ⁇ st, so that light emission can be obtained by the strain. This is also clear from the results shown in FIG. 6, and it can be said that the stress-stimulated luminescent material according to this embodiment can detect a pN-order force.
  • the stress-stimulated luminescent material according to the present embodiment is placed inside or outside a cell that stretches or contracts, for example, muscle cells
  • the time-dependent changes in stress and movement inside and outside the cell are emitted by light emission according to the stretching and contracting operation of the cell. It is also possible to observe the strength of the stress and movement by the intensity of the observation.
  • the distribution of the predetermined substance inside and outside the cell has been detected by light, but there is no example of visualizing the force and movement applied inside and outside the cell, and it can be said that it is extremely innovative.
  • the stress-stimulated luminescent material according to this embodiment can be used as a single-phase stress-stimulated luminescent material using a piezoelectric material as a base material, which can emit light with high sensitivity even with a minute force due to stress, molecular motion, or natural vibration. have.
  • a part of Li constituting the crystal of LiNbO 3 is replaced with at least one metal ion selected from rare earth metal ions and transition metal ions. Therefore, it is possible to provide a single-phase stress luminescent material using a piezoelectric material as a base material, which can emit light with high sensitivity even for a minute stress.

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Abstract

Provided is a single-phase stress light-emitting material which is capable of emitting light with high sensitivity even under small stress, and uses a piezoelectric material as a host material. The single-phase stress light-emitting material is characterized in that some of the Li atoms constituting a LiNbO3 crystal are substituted by at least one kind of metal ion selected from among rare earth metal ions and transition metal ions. The single-phase stress light-emitting material is also characterized by having a nonstoichiometric composition represented by general formula LixNbO3:My, wherein: x=1-y and 0.0001≤y≤0.2, or x>1-y and 0.0001≤y≤0.2; 0.8<x≤3.0; and said metal ion is Pr3+.

Description

応力発光材料、及び応力発光体、並びに応力発光材料の使用Stress luminescent material, stress luminescent material, and use of stress luminescent material
　本発明は、応力発光材料、及び応力発光体、並びに応力発光材料の使用に関する。 The present invention relates to the use of a stress luminescent material, a stress luminescent material, and a stress luminescent material.
　従来、応力発光材料は、外部から力学的な刺激によって、そのエネルギーに相関したルミネッセンスを放出する材料として知られており、センサ、非破壊検査、応力分布の可視化、ストレスセンシング、および構造物の異常・危険検知など実に様々な用途が期待されている。 Traditionally, stress-stimulated luminescent materials are known as materials that emit luminescence correlated to their energy by mechanical stimuli from the outside. Sensors, nondestructive inspection, visualization of stress distribution, stress sensing, and structural abnormalities・ Various uses such as danger detection are expected.
　それゆえ、これまでに紫外領域波長から近赤外領域波長まで、様々な波長で応力に応じた発光が可能な応力発光材料の開発がなされている。 Therefore, stress luminescent materials that can emit light according to stress at various wavelengths from the ultraviolet region wavelength to the near infrared region wavelength have been developed so far.
　なかでも、圧電体を母体材料とした応力発光材料は、さらに様々な電子制御機能が可能になることや、電気、力、光の多元変換可能という長所があるため、種々検討されている。 In particular, stress-stimulated luminescent materials using a piezoelectric material as a base material have been studied in various ways because of their advantages of enabling various electronic control functions and the ability to perform multiple conversion of electricity, force, and light.
　しかし、これまでに検討された圧電体を母体材料とする応力発光材料は、応力発光強度が比較的高いものについては圧電性が弱く、また、強い圧電体を母体材料とするものにあっては応力発光強度が弱いという傾向がある。 However, the stress-stimulated luminescent materials based on the piezoelectric material studied so far have weak piezoelectricity when the stress luminescence intensity is relatively high, and those that use a strong piezoelectric material as the base material. There is a tendency that the stress emission intensity is weak.
　そこで、本発明者らは鋭意研究を行い、複数の結晶構造が混在してなる混相として発光強度の改善を図ったものを過去に提案している（例えば、特許文献１参照。）。 Therefore, the present inventors have conducted intensive research and have proposed in the past what the emission intensity has been improved as a mixed phase composed of a plurality of crystal structures (see, for example, Patent Document 1).
特開２０１０－７７４３７号公報JP 2010-77437 A
　しかしながら、上記従来の応力発光材料は混相で構成されるものであり、圧電体でありながら単相の応力発光材料については、これまで知られていない。 However, the conventional stress-stimulated luminescent material is composed of a mixed phase, and a single-phase stress-stimulated luminescent material is not known so far although it is a piezoelectric body.
　また、構造物の異常・危険検知に関し、欠陥の危険レベルを予知すべく応力集中を高感度に検知できる応力発光材料の開発が期待されるところ、上記従来の混相とした応力発光材料であってもひずみ検知する閾値は高く、1万分の1以下のような小ひずみ（0-100μst)で発光することは困難であった。 In addition, regarding the detection of structural abnormalities and dangers, the development of stress-stimulated luminescent materials that can detect stress concentration with high sensitivity to predict the risk level of defects is expected. However, the threshold for strain detection was high, and it was difficult to emit light with a small strain (0-100 μst) of 1 / 10,000 or less.
　本発明は、斯かる事情に鑑みてなされたものであって、微小な力に対しても高感度で発光が可能な、圧電体を母体材料とする単相の応力発光材料を提供する。 The present invention has been made in view of such circumstances, and provides a single-phase stress luminescent material using a piezoelectric material as a base material, which can emit light with high sensitivity even with a minute force.
　また、本発明では、応力発光材料を所定のマトリクス材料中に分散してなる応力発光体や、応力発光材料の使用、応力発光材料の製造方法についても提供する。 The present invention also provides a stress luminescent material obtained by dispersing a stress luminescent material in a predetermined matrix material, a use of the stress luminescent material, and a method of manufacturing the stress luminescent material.
　上記従来の課題を解決するために、本発明に係る応力発光材料では、（１）LiNbO3の結晶体を構成する一部のLiが、希土類金属イオン及び遷移金属イオンから選ばれる少なくとも１種の金属イオンにより置換されることとした。 In order to solve the above conventional problems, in the stress-stimulated luminescent material according to the present invention, (1) a part of Li constituting the crystal of LiNbO 3 is at least one selected from rare earth metal ions and transition metal ions. It was decided to be replaced by metal ions.
　また、本発明に係る応力発光材料では、以下の点にも特徴を有する。
（２）一般式LixNbO3:My（ただし、Mは、LiNbO3の結晶体を構成する一部のLiを置換する希土類金属イオン及び遷移金属イオンから選ばれる少なくとも１種の金属イオン。）で表される非化学量論的組成を有し、x=1-yであって、0.0001≦y≦0.2であること。
（３）一般式LixNbO3:My（ただし、Mは、LiNbO3の結晶体を構成する一部のLiを置換する希土類金属イオン及び遷移金属イオンから選ばれる少なくとも１種の金属イオン。）で表される非化学量論的組成を有し、x＞1-yであって、0.0001≦y≦0.2であること。
（４）0.8＜x≦3.0であること。
（５）前記金属イオンは、Pr3+であること。 The stress-stimulated luminescent material according to the present invention is also characterized by the following points.
(2) General formula Li x NbO 3 : M y (where M is at least one metal ion selected from a rare earth metal ion and a transition metal ion replacing a part of Li constituting the crystal of LiNbO 3 . And non-stoichiometric composition, x = 1−y, and 0.0001 ≦ y ≦ 0.2.
(3) General formula Li x NbO 3 : M y (where M is at least one metal ion selected from a rare earth metal ion and a transition metal ion replacing a part of Li constituting the crystal of LiNbO 3 . ), X> 1-y, and 0.0001 ≦ y ≦ 0.2.
(4) 0.8 <x ≦ 3.0.
(5) The metal ion is Pr 3+ .
　また、本発明に係る応力発光体では、（６）上記（１）～（５）のいずれかに記載の応力発光材料が所定のマトリクス材料中に分散されていることに特徴を有する。 The stress-stimulated luminescent material according to the present invention is characterized in that (6) the stress-stimulated luminescent material described in any one of (1) to (5) is dispersed in a predetermined matrix material.
　また、本発明では、（７）1000pN以下の力を発光により検出するための上記（１）～（５）のいずれかに記載の応力発光材料の使用に特徴を有する。 Further, the present invention is characterized by (7) the use of the stress-stimulated luminescent material according to any one of the above (1) to (5) for detecting a force of 1000 pN or less by luminescence.
　また、本発明では、（８）100μst以下の微小ひずみを発光により検知するための上記（１）～（５）のいずれかに記載の応力発光材料の使用に特徴を有する。 Further, the present invention is characterized in that (8) the stress-stimulated luminescent material described in any one of (1) to (5) above is used to detect minute strains of 100 μst or less by light emission.
　また、本発明に係る応力発光材料の製造方法では、ニオブ化合物と、リチウム化合物と、希土類金属及び遷移金属から選ばれる少なくとも１種の金属の化合物とを混合して焼成するLiNbO3を母体材料とした応力発光材料の製造方法であって、ニオブ原子とリチウム原子とのモル比を１：0.8～3.0とすることに特徴を有する。 In the method for producing a stress-stimulated luminescent material according to the present invention, the base material is LiNbO 3 which is obtained by mixing and firing a niobium compound, a lithium compound, and a compound of at least one metal selected from rare earth metals and transition metals. The method for producing a stress-stimulated luminescent material is characterized in that the molar ratio of niobium atoms to lithium atoms is 1: 0.8 to 3.0.
　本発明に係る応力発光材料によれば、LiNbO3の結晶体を構成する一部のLiが、希土類金属イオン及び遷移金属イオンから選ばれる少なくとも１種の金属イオンにより置換されることとしたため、微小な力に対しても高感度で発光が可能な、圧電体を母体材料とする単相の応力発光材料を提供することができる。 According to the stress-stimulated luminescent material according to the present invention, a part of Li constituting the LiNbO 3 crystal is replaced with at least one metal ion selected from rare earth metal ions and transition metal ions. It is possible to provide a single-phase stress luminescent material using a piezoelectric material as a base material and capable of emitting light with high sensitivity even for a large force.
　また、一般式LixNbO3:My（ただし、Mは、LiNbO3の結晶体を構成する一部のLiを置換する希土類金属イオン及び遷移金属イオンから選ばれる少なくとも１種の金属イオン。）で表される非化学量論的組成を有し、x=1-yであって、0.0001≦y≦0.2であることとすれば、応力に応じた発光をより堅実に生起させることができる。 Further, the general formula Li x NbO 3 : M y (where M is at least one metal ion selected from a rare earth metal ion and a transition metal ion substituting for a part of Li constituting the crystal of LiNbO 3 ) When x = 1−y and 0.0001 ≦ y ≦ 0.2, the light emission according to the stress can be caused more steadily.
　また、一般式LixNbO3:My（ただし、Mは、LiNbO3の結晶体を構成する一部のLiを置換する希土類金属イオン及び遷移金属イオンから選ばれる少なくとも１種の金属イオン。）で表される非化学量論的組成を有し、x＞1-yであって、0.0001≦y≦0.2であることとすれば、発光強度をより向上させることができる。 Further, the general formula Li x NbO 3 : M y (where M is at least one metal ion selected from a rare earth metal ion and a transition metal ion substituting for a part of Li constituting the crystal of LiNbO 3 ) The emission intensity can be further improved if x> 1-y and 0.0001 ≦ y ≦ 0.2.
　また、0.8＜x≦3.0であることとすれば、発光強度をより堅実に向上させることができる。 Moreover, if 0.8 <x ≦ 3.0, the emission intensity can be improved more steadily.
　また、前記金属イオンは、Pr3+であることとすれば、応力に応じた発光を更に堅実に生起させることができる。 Further, if the metal ion is Pr 3+ , light emission according to stress can be caused more steadily.
　また、本発明に係る応力発光体によれば、これらの応力発光材料が所定のマトリクス材料中に分散されていることとしたため、応力を受けることにより発光する応力発光体を提供することができる。 Also, according to the stress-stimulated luminescent material according to the present invention, since these stress-stimulated luminescent materials are dispersed in a predetermined matrix material, it is possible to provide a stress-stimulated luminescent material that emits light when subjected to stress.
　また、1000pN以下の力を発光により検出するために、上述の応力発光材料を使用すれば、1000pN以下の微小な力を発光により検出することができる。 Also, in order to detect a force of 1000 pN or less by light emission, a minute force of 1000 pN or less can be detected by light emission if the above-described stress light emitting material is used.
　また、100μst以下の微小ひずみを発光により検知するために、上述の応力発光材料を使用すれば、100μst以下の微小ひずみを発光により検知することができる。 Also, in order to detect a micro strain of 100 μst or less by light emission, if the above-described stress light emitting material is used, a micro strain of 100 μst or less can be detected by light emission.
　また、本発明に係る応力発光材料の製造方法によれば、ニオブ化合物と、リチウム化合物と、希土類金属及び遷移金属から選ばれる少なくとも１種の金属の化合物とを混合して焼成するLiNbO3を母体材料とした応力発光材料の製造方法であって、ニオブ原子とリチウム原子とのモル比を１：0.8～3.0とすることとしたため、微小な応力に対しても高感度で発光が可能な、圧電体を母体材料とする単相の応力発光材料を製造することができる。 In addition, according to the method for producing a stress-stimulated luminescent material according to the present invention, LiNbO 3 is obtained by mixing and firing a niobium compound, a lithium compound, and a compound of at least one metal selected from rare earth metals and transition metals. A method for producing a stress-stimulated luminescent material, wherein the molar ratio of niobium atoms to lithium atoms is set to 1: 0.8 to 3.0. A single-phase stress luminescent material having a body as a base material can be manufactured.
X線回折装置による結晶相の同定結果を示す説明図である。It is explanatory drawing which shows the identification result of the crystal phase by a X-ray-diffraction apparatus. 蛍光分光スペクトル測定結果、応力発光スペクトル（ａ）、及びPrドープ量と蛍光強度との関係（ｂ）を示す説明図である。It is explanatory drawing which shows the relationship (b) of a fluorescence spectroscopy spectrum measurement result, a stress luminescence spectrum (a), and the amount of Pr dope, and fluorescence intensity. 応力発光体を応力発光評価システムに供して得られた応力発光曲線（ａ）、及びPrドープ量と応力発光強度との関係（ｂ）を示す説明図である。It is explanatory drawing which shows the relationship (b) of the stress light emission curve (a) obtained by using a stress light-emitting body for a stress light-emission evaluation system, and Pr dope amount and stress light emission intensity. X線回折装置による結晶相と計算した格子定数の結果を示す説明図である。It is explanatory drawing which shows the result of the lattice constant calculated with the crystal phase by an X-ray-diffraction apparatus. 応力発光体を応力発光評価システムに供して得られた応力発光曲線を示す説明図である。It is explanatory drawing which shows the stress light emission curve obtained by using a stress light-emitting body for a stress light-emission evaluation system. ひずみに対する発光強度の変化を示した説明図である。It is explanatory drawing which showed the change of the emitted light intensity with respect to distortion. 荷重と発光強度との経時変化を示した説明図（ａ）、及び応力発光強度分布と応力分布の定量解析結果との比較を示した説明図（ｂ）である。It is explanatory drawing (a) which showed the time-dependent change of a load and luminescence intensity, and explanatory drawing (b) which showed the comparison with the quantitative analysis result of stress luminescence intensity distribution and stress distribution. X線回折装置による結晶相の同定結果を示す説明図である。It is explanatory drawing which shows the identification result of the crystal phase by a X-ray-diffraction apparatus. 応力発光体を応力発光評価システムに供して得られた応力発光曲線を示す説明図である。It is explanatory drawing which shows the stress light emission curve obtained by using a stress light-emitting body for a stress light-emission evaluation system. Eu3+, Er3+, Nd3+をドープした場合の応力発光強度を示す説明図である。It is explanatory drawing which shows the stress luminescence intensity at the time of doping with Eu3 + , Er3 + , Nd3 + .
　本発明は、LiNbO3の結晶体を構成する一部のLiが、希土類金属イオン及び遷移金属イオンから選ばれる少なくとも１種の金属イオンにより置換された応力発光材料を提供するものである。 The present invention provides a stress-stimulated luminescent material in which a part of Li constituting a crystal of LiNbO 3 is substituted with at least one metal ion selected from rare earth metal ions and transition metal ions.
　先に述べたように、応力発光体は力学的刺激によってそのエネルギーに相関したルミネセンスを示す材料であり、様々な分野への応用が期待されている。 As described above, a stress-stimulated luminescent material is a material that exhibits luminescence correlated with its energy by mechanical stimulation, and is expected to be applied in various fields.
　本発明者はこれまでに様々な応力発光体を開発してきており、圧電体を母体材料とする応力発光体についても研究を行ってきたが、PZTなどの有名な圧電体では応力発光を確認できず、Ba1-xCaxTiO3:Pr3+は応力に応答して発光したが、これは圧電相とエレクトロルミネッセンス相の複合作用によるもので、単相での応力発光は実現できていなかった。すなわち、母体材料として典型的な圧電体を用いたものは良好な応力発光を示さない、というのがこれまでの結果であった。 The present inventor has developed various stress light emitters, and has also studied a stress light emitter using a piezoelectric material as a base material. However, stress emission can be confirmed with famous piezoelectric materials such as PZT. In addition, Ba 1-x Ca x TiO 3 : Pr 3+ emitted light in response to stress, but this was due to the combined action of the piezoelectric phase and the electroluminescence phase, and stress emission in a single phase could not be realized. It was. That is, the results so far have shown that a material using a typical piezoelectric material as a base material does not exhibit good stress luminescence.
　一方、LiNbO3は高いキュリー温度を持つ強誘電体であり、その圧電特性、電気光学特性、非線形光学特性のため長らく注目されており、現在は優れた電気・光学材料として多岐にわたり利用されている。 On the other hand, LiNbO 3 is a ferroelectric substance with a high Curie temperature, and has been attracting attention for a long time because of its piezoelectric characteristics, electro-optical characteristics, and nonlinear optical characteristics, and is currently widely used as an excellent electro / optical material. .
　本発明者らは、鋭意研究によりこのLiNbO3にPr3+をドープすることで、応力発光体としての機能が発現することを初めて発見し、本発明を完成させるに至ったものである。 The inventors of the present invention have discovered for the first time that the function as a stress-stimulated luminescent material is expressed by doping Pr 3+ into LiNbO 3 through intensive studies, and have completed the present invention.
　すなわち、本発明は、高い圧電特性と応力発光特性の両方を示す最初の材料であるPr3+がドープされたLiNbO3を母体材料とする応力発光材料に関するものとも言える。 That is, it can be said that the present invention relates to a stress-stimulated luminescent material using as a base material LiNbO 3 doped with Pr 3+, which is the first material exhibiting both high piezoelectric characteristics and stress-stimulated luminescent characteristics.
　また、本実施形態に係る応力発光材料は、圧電性を有する母体材料でありながら、単相であることが特徴的である。なお、ここで単相とは、他の結晶相によらず単一種の結晶相で励起から発光までが完結していることをいうものであり、生成された応力発光材料に不純物相を含まないことを必ずしも意味しているのではない。つまり、本実施形態に係る応力発光材料に特徴的な結晶相、すなわち、LiNbO3の結晶体を構成する一部のLiが、希土類金属イオン及び遷移金属イオンから選ばれる少なくとも１種の金属イオンにより置換された応力発光相が含まれていれば、他の不純物相の有無にかかわらず、応力発光特性を有することとなる。 In addition, the stress-stimulated luminescent material according to the present embodiment is characterized by being a single phase while being a base material having piezoelectricity. Here, the single phase means that a single type of crystal phase is completed from excitation to light emission regardless of other crystal phases, and the generated stress luminescent material does not contain an impurity phase. It does not necessarily mean that. That is, the crystalline phase characteristic of the stress-stimulated luminescent material according to the present embodiment, that is, a part of Li constituting the LiNbO 3 crystal is formed by at least one metal ion selected from rare earth metal ions and transition metal ions. If the substituted stress emission phase is included, the stress emission property is obtained regardless of the presence or absence of other impurity phases.
　本実施形態に係る応力発光材料において希土類金属イオンは、例えば、Sc(スカンジウム)、Y（イットリウム）、La（ランタン）、Ce（セリウム）、Pr（プラセオジム）、Nd（ネオジム）、Pm（プロメチウム）、Sm（サマリウム）、Eu（ユウロピウム）、Gd（ガドリニウム）、Tb（テルビウム）、Dy（ジスプロシウム）、Ho（ホルミウム）、Er（エルビウム）、Tm（ツリウム）、Yb（イッテルビウム）、Lu（ルテチウム）のイオンと解することができる。 In the stress-stimulated luminescent material according to the present embodiment, for example, Sc (scandium), Y (yttrium), La (lanthanum), Ce (cerium), Pr (praseodymium), Nd (neodymium), Pm (promethium) , Sm (samarium), Eu (europium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Yb (ytterbium), Lu (lutetium) It can be understood that
　また、遷移金属イオンは、第3族元素から第11族元素の間に存在する遷移金属のイオンと解することができる。 Also, transition metal ions can be interpreted as transition metal ions existing between Group 3 elements and Group 11 elements.
　本実施形態に係る応力発光材料において、LiNbO3の結晶体を構成する一部のLiを置換するために用いられる金属イオンは、上述した希土類金属イオンや遷移金属イオンであれば、特に限定されるものではない。 In the stress-stimulated luminescent material according to the present embodiment, the metal ions used for substituting a part of Li constituting the LiNbO 3 crystal are particularly limited as long as they are the rare earth metal ions and transition metal ions described above. It is not a thing.
　そして、このような応力発光材料によれば、微小な応力に対しても高感度で発光が可能な、圧電体を母体材料とする単相の応力発光材料とすることができる。 Further, according to such a stress-stimulated luminescent material, it is possible to obtain a single-phase stress-stimulated luminescent material using a piezoelectric body as a base material, which can emit light with high sensitivity even with a minute stress.
　また、本実施形態に係る応力発光材料は、一般式LixNbO3:My（ただし、Mは、LiNbO3の結晶体を構成する一部のLiを置換する希土類金属イオン及び遷移金属イオンから選ばれる少なくとも１種の金属イオン。）で表される非化学量論的組成を有し、x=1-yであって、0.0001≦y≦0.2であることとしても良い。 In addition, the stress-stimulated luminescent material according to the present embodiment has a general formula Li x NbO 3 : M y (where M is a rare earth metal ion and a transition metal ion substituting a part of Li constituting the crystal of LiNbO 3. At least one metal ion selected)), and x = 1−y, and 0.0001 ≦ y ≦ 0.2.
　ここで、yが0.0001未満となると、発光強度が著しく低下するため好ましくない。また、yが0.2を超えると、不純物の割合は高くなり、応力発光するLiNbO3結晶相の割合は減少するため応力発光強度は減少することとなり好ましくない。0.0001≦y≦0.2とすることにより、応力に応じた発光をより堅実に生起させることができる。 Here, it is not preferable that y is less than 0.0001 because the emission intensity is significantly reduced. On the other hand, if y exceeds 0.2, the ratio of impurities increases, and the ratio of the LiNbO 3 crystal phase that emits stress light decreases, so that the stress light emission intensity decreases, which is not preferable. By setting 0.0001 ≦ y ≦ 0.2, light emission according to the stress can be caused more firmly.
　また、本実施形態に係る応力発光材料は、一般式LixNbO3:Myで表される非化学量論的組成を有し、x＞1-yであって、0.0001≦y≦0.2であることとしても良い。 Further, the stress light-emitting material according to the present embodiment, the general formula Li x NbO 3: having a non-stoichiometric composition represented by M y, x> a 1-y, with 0.0001 ≦ y ≦ 0.2 It is good to be.
　これは後に図面を参照しつつ説明するが、本発明者らが見出した特筆すべき構成の一つであり、LiNbO3の結晶構造を構築する上で必要なリチウムよりも、リチウムと金属イオンとの和を大きくして過剰量存在させることにより、発光強度をより向上させ発光効率を高めることができる Although this will be described later with reference to the drawings, it is one of the notable configurations found by the present inventors, and more than lithium and metal ions than lithium necessary for constructing the crystal structure of LiNbO 3. By increasing the sum of the two and making it exist in an excessive amount, the emission intensity can be further improved and the luminous efficiency can be increased.
　また、このときのxは、0.8＜x≦3.0としても良い。このような構成とすることにより、極めて高効率に発光する応力発光材料とすることができる。 Also, x at this time may be 0.8 <x ≦ 3.0. With such a configuration, a stress light emitting material that emits light with extremely high efficiency can be obtained.
　また、金属イオンはPr3+としても良い。このような構成とすることにより、応力に応じた発光を更に堅実に高効率で生起させることができる。 The metal ion may be Pr 3+ . By adopting such a configuration, it is possible to cause light emission according to stress to occur more stably and efficiently.
　そしてこのような構成を備えた本実施形態に係る応力発光材料は、極めて高い応力応答性を備えているため、例えば、1000pN以下の力を発光により検出するため使用することができる。 Since the stress-stimulated luminescent material according to the present embodiment having such a configuration has extremely high stress responsiveness, for example, it can be used to detect a force of 1000 pN or less by luminescence.
　また、例えば、100μst以下の微小ひずみを発光により検知するために使用することができる。 Also, for example, it can be used to detect minute strains of 100 μst or less by light emission.
　また、上述した本実施形態に係る応力発光材料は、所定のマトリクス材料中に分散させて応力発光体を形成させても良い。例えば、硬化性を有する樹脂をマトリクス材料とし、硬化前の樹脂中に粉末状の応力発光材料を分散させ硬化させることにより、応力を付与することで発光を示す所望の形状の応力発光体を容易に形成することができる。なお、マトリクス材料は少なくとも、同マトリクス材料中に混在させた応力発光材料を励起させるための励起光や、応力発光材料から放射される蛍光が透過可能なものが用いられる。 Further, the stress-stimulated luminescent material according to this embodiment described above may be dispersed in a predetermined matrix material to form a stress-stimulated luminescent material. For example, a stress-stimulated luminescent material that emits light by applying stress can be easily obtained by dispersing and curing a powdered stress-stimulated luminescent material in the resin before curing, using a curable resin as a matrix material. Can be formed. Note that at least the matrix material that can transmit the excitation light for exciting the stress luminescent material mixed in the matrix material and the fluorescence emitted from the stress luminescent material is used.
　また、応力発光体は、固体に限られず、流動性を有する液体状の物であっても良い。具体的には、本実施形態に係る応力発光材料を混入させた塗料なども応力発光体の概念に含まれる。 Further, the stress-stimulated luminescent material is not limited to a solid, and may be a liquid material having fluidity. Specifically, a paint containing the stress-stimulated luminescent material according to this embodiment is also included in the concept of the stress-stimulated luminescent material.
　また、本実施形態に係る応力発光材料の製造方法は、ニオブ化合物と、リチウム化合物と、希土類金属及び遷移金属から選ばれる少なくとも１種の金属の化合物とを混合して焼成するLiNbO3を母体材料とした応力発光材料の製造方法であって、ニオブ原子とリチウム原子とのモル比を１：0.8～3.0とすることを特徴としている。 In addition, the method for producing a stress-stimulated luminescent material according to the present embodiment is based on LiNbO 3 obtained by mixing and firing a niobium compound, a lithium compound, and a compound of at least one metal selected from a rare earth metal and a transition metal. The stress-luminescent material manufacturing method is characterized in that the molar ratio of niobium atoms to lithium atoms is 1: 0.8 to 3.0.
　ここで、ニオブ化合物は、混合や焼成過程を経てLiNbO3の結晶を構築可能な化合物であれば特に限定されるものではなく、例えば、Nb2O5やNbCl5、NbF5等とすることができる。 Here, the niobium compound is not particularly limited as long as it is a compound capable of constructing a LiNbO 3 crystal through mixing and firing processes. For example, Nb 2 O 5 , NbCl 5 , NbF 5, etc. it can.
　また、リチウム化合物も同様に、LiNbO3の結晶を構築可能な化合物であれば特に限定されるものではなく、例えば、Li2CO3やLiNO3、LiCl等とすることができる。 Similarly, the lithium compound is not particularly limited as long as it is a compound capable of constructing a LiNbO 3 crystal. For example, it can be Li 2 CO 3 , LiNO 3 , LiCl, or the like.
　また、希土類金属及び遷移金属から選ばれる少なくとも１種の金属の化合物についても特に限定されるものではなく、同金属の酸化物等を用いることができ、例えば金属としてPrを選択した場合には、Pr2O3やPrCl3、Pr(NO3)3等とすることができる。 Further, the compound of at least one metal selected from rare earth metals and transition metals is not particularly limited, and an oxide of the same metal can be used. For example, when Pr is selected as the metal, Pr 2 O 3 , PrCl 3 , Pr (NO 3 ) 3 and the like can be used.
　なお、上述の各化合物は、必ずしもそれぞれ別個の化合物を用いる必要はなく、いずれか２つの元素を含む化合物などがあれば、そのような化合物を利用することも可能である。 In addition, it is not always necessary to use a separate compound for each of the above-described compounds. If there is a compound containing any two elements, it is possible to use such a compound.
　これらの化合物の混合は、乾式、湿式を問わず公知の合成方法に準じて行うことができる。一例を挙げるならば、固相合成法により行うようにしても良い。 These compounds can be mixed according to known synthesis methods regardless of whether they are dry or wet. For example, the solid phase synthesis method may be used.
　また、本実施形態に係る応力発光材料の製造方法において特徴的には、ニオブ原子とリチウム原子とのモル比を１：0.8～3.0、より限定的には１：0.95～2.4とする点が挙げられる。 In addition, the method for producing a stress-stimulated luminescent material according to this embodiment is characterized in that the molar ratio of niobium atoms to lithium atoms is 1: 0.8 to 3.0, more specifically 1: 0.95 to 2.4. It is done.
　ニオブ原子の比率１に対して、リチウム原子の比率が0.8を下回ると発光効率が著しく低下するため好ましくない。また、リチウム原子の比率が3.0を上回ると、発光効率の低下が顕著に現れるため好ましくない。ニオブ原子とリチウム原子とのモル比を１：0.8～3.0、より好ましくは１：0.95～2.4とすることにより、応力に対して極めて高効率に応答する応力発光材料を製造することができる。 When the ratio of lithium atoms is less than 0.8 with respect to the ratio of niobium atoms of 1, the luminous efficiency is remarkably lowered, which is not preferable. On the other hand, if the ratio of lithium atoms exceeds 3.0, a decrease in luminous efficiency appears remarkably, which is not preferable. By setting the molar ratio of niobium atoms to lithium atoms to 1: 0.8 to 3.0, more preferably 1: 0.95 to 2.4, a stress-stimulated luminescent material that responds extremely efficiently to stress can be produced.
　以下、本実施形態に係る応力発光材料について、図面を参照しながら更に説明する。 Hereinafter, the stress-stimulated luminescent material according to this embodiment will be further described with reference to the drawings.
〔１．応力発光材料の調製〕
　試料の調製は固相合成法によって行った。ニオブ化合物としてNb2O5、リチウム化合物としてLi2CO3、希土類金属及び遷移金属から選ばれる少なくとも１種の金属の化合物としてPr2O3を用い、LixNbO3:Pr3+ yのx及びyが目的組成になるよう秤量後、メノウ乳鉢で混合・粉砕した。xは、0.8＜x≦3.0の範囲内で調整し、yは、0.0001≦y≦0.2の範囲内で調整した。 [1. Preparation of stress luminescent material
Samples were prepared by solid phase synthesis. Nb 2 O 5 as a niobium compound, Li 2 CO 3 as a lithium compound, Pr 2 O 3 as a compound of at least one metal selected from rare earth metals and transition metals, and Li x NbO 3 : Pr 3+ y x And weighed so that y had the target composition, and then mixed and ground in an agate mortar. x was adjusted within the range of 0.8 <x ≦ 3.0, and y was adjusted within the range of 0.0001 ≦ y ≦ 0.2.
　次いで、これらを電気炉で焼成することで試料の調製を行った。焼成に際し、反応前駆体粉末を油圧機でペレット状に成型し、焼成を行った。焼成はマッフル炉で、焼成条件は大気中で1050℃で8時間、昇温速度は3℃/minとした。焼成後の試料を乳鉢で粉砕し、本実施形態に係る応力発光材料の粉末状のものとして各種測定に供した。 Next, samples were prepared by firing them in an electric furnace. At the time of firing, the reaction precursor powder was formed into pellets with a hydraulic machine and fired. Firing was performed in a muffle furnace, the firing conditions were 1050 ° C. for 8 hours in the air, and the heating rate was 3 ° C./min. The fired sample was pulverized in a mortar and subjected to various measurements as a powdered material of the stress-stimulated luminescent material according to this embodiment.
〔２．LixNbO3:Pr3+ y（x=1, 0≦y≦0.1）の検討〕
　上記〔１．応力発光材料の調製〕に従い、LixNbO3:Pr3+ y（x=1, 0≦y≦0.1）の調製を行った。調製した試料は粉末X線回折装置により結晶相の同定を行った。その結果を図１に示す。 [2. Li x NbO 3 : Pr 3+ y (examination of x = 1, 0 ≦ y ≦ 0.1)]
[1. Preparation of Stress Luminescent Material] Li x NbO 3 : Pr 3+ y (x = 1, 0 ≦ y ≦ 0.1) was prepared. The prepared sample was identified by a powder X-ray diffractometer. The result is shown in FIG.
　図１からも分かるように、いずれのドープ量でもLiNbO3の生成を確認できた。また、Pr3+ドープ量を2mol％未満とした試料では、図１における0.5mol%のチャートに示すように、不純物相に由来する顕著なピークは確認されなかった。一方、Pr3+ドープ量を2mol％～10mol％とした試料では、図１における10mol%のチャートに示すように、不純物相に由来すると考えられるピークが観察された。また、0mol％～0.5mol％の低ドープ量の試料では結晶相に若干の配向性がみられた。 As can be seen from FIG. 1, the formation of LiNbO 3 was confirmed at any doping amount. Further, in the sample in which the Pr 3+ doping amount was less than 2 mol%, as shown in the 0.5 mol% chart in FIG. 1, no significant peak derived from the impurity phase was confirmed. On the other hand, in the sample in which the Pr 3+ dope amount was 2 mol% to 10 mol%, as shown in the 10 mol% chart in FIG. 1, a peak considered to be derived from the impurity phase was observed. In addition, in the samples with a low dope amount of 0 mol% to 0.5 mol%, a slight orientation was observed in the crystal phase.
　次に、蛍光分光光度計により蛍光特性を評価した。図２（ａ）に蛍光分光測定結果を示す。発光中心であるPr3+をドープしてないものでは蛍光は確認できず、Pr3+をドープすると、図２（ａ）に示すように、620nm付近に発光ピークが観察された。また、Pr3+ドープ量に対する蛍光特性は、図２（ｂ）に示すように、LixNbO3:Pr3+ yについてx=1, y=0.001のときに最大の約160[a.u.]を示し、x=1, y=0.005のときに約120[a.u.]、x=1, y=0.01のときに約150[a.u.]、x=1, y=0.02～0.05のときに約100[a.u.]、x=1, y=0.1のときに約85[a.u.]を示した。 Next, the fluorescence characteristics were evaluated using a fluorescence spectrophotometer. FIG. 2A shows the result of fluorescence spectroscopy measurement. But not doped with Pr 3+ as an emission center of the fluorescent can not be confirmed, when doped with Pr 3+, as shown in FIG. 2 (a), the emission peak was observed around 620 nm. The fluorescent characteristics for Pr 3+ doping amount, as shown in FIG. 2 (b), Li x NbO 3: up to about 160 when about Pr 3+ y x = 1, y = 0.001 to [au] About 120 [au] when x = 1, y = 0.005, about 150 [au] when x = 1, y = 0.01, about 100 [au when x = 1, y = 0.02 to 0.05 ], X = 1, y = 0.1 showed about 85 [au].
　次に、応力発光特性について評価を行った。応力発光特性は、焼成試料と樹脂を混合し円柱形の樹脂ペレット（直径：2.5 cm、高さ：1.5 cm）を作成して応力発光体とし、応力発光評価システムにより評価した。測定方法は、樹脂ペレットに対し垂直方向の荷重を印加し、その時の発光強度をフォトンセンサで測定した。その結果を図３に示す。 Next, the stress emission characteristics were evaluated. The stress luminescence property was evaluated by a stress luminescence evaluation system by preparing a cylindrical resin pellet (diameter: 2.5 cm, height: 1.5 cm) by mixing a fired sample and a resin to obtain a stress luminescent material. The measuring method applied the load of the perpendicular direction with respect to the resin pellet, and measured the emitted light intensity at that time with the photon sensor. The result is shown in FIG.
　図３（ａ）は、各試料の応力発光曲線である。Pr3+をドープしていない試料では全く発光を示していない。一方、Pr3+をドープした試料では、印加荷重の増加に従った応力発光が確認できた。また、ドープ量の増加とともに応力発光強度が増加することが観察され、今回調製した試料では5mol％のものが最も高い応力発光強度を示した。特に、蛍光強度では、図２（ｂ）にて示したように、0.5mol%添加試料よりも、5mol%添加試料の方が蛍光発光強度が低かったのに対し、応力発光強度では0.5mol%添加試料よりも、5mol%添加試料の方が発光強度が高いという結果が得られた点は興味深い。また、LixNbO3:Pr3+ y（x=1, [y=0.001, 0.005, 0.01, 0.02, 0.03, 0.05, 0.1]）について、Pr3+ドープ量と応力発光強度との関係について検討したところ、5mol%(y=0.05)までは大凡ドープ量に応じて応力発光強度が高くなる傾向が見られたが、10mol%(y=0.1)では応力発光強度が低下することが確認された。 FIG. 3A shows a stress emission curve of each sample. The sample not doped with Pr 3+ shows no light emission. On the other hand, in the sample doped with Pr 3+ , stress luminescence according to the increase in applied load was confirmed. In addition, it was observed that the stress emission intensity increased with an increase in the dope amount, and in the sample prepared this time, the one with 5 mol% showed the highest stress emission intensity. In particular, as shown in FIG. 2 (b), the fluorescence intensity of the fluorescence intensity was lower in the sample added with 5 mol% than that in the sample added with 0.5 mol%, whereas it was 0.5 mol% in the stress emission intensity. It is interesting to note that the 5 mol% added sample has a higher emission intensity than the added sample. In addition, for Li x NbO 3 : Pr 3+ y (x = 1, [y = 0.001, 0.005, 0.01, 0.02, 0.03, 0.05, 0.1]), the relationship between the Pr 3+ doping amount and the stress emission intensity was examined. As a result, up to 5 mol% (y = 0.05), the stress emission intensity tended to increase according to the amount of doping, but it was confirmed that the stress emission intensity decreased at 10 mol% (y = 0.1). .
〔３．LixNbO3:Pr3+ y（0.95≦x≦1.05, y=0.01）の検討〕
　前述の〔１．応力発光材料の調製〕に従い、LixNbO3:Pr3+ y（0.95≦x≦1.05, y=0.01）の調製を行った。調製した試料は粉末X線回折装置により結晶相の同定を行った。その結果を図４に示す。 [3. Li x NbO 3 : Pr 3+ y (0.95 ≦ x ≦ 1.05, y = 0.01)
[1. Preparation of Stress Luminescent Material] Li x NbO 3 : Pr 3+ y (0.95 ≦ x ≦ 1.05, y = 0.01) was prepared. The prepared sample was identified by a powder X-ray diffractometer. The result is shown in FIG.
　図４（ａ）からも分かるように、LixNbO3:Pr3+ y（[x=0.95, 0.97, 0.99, 1.00], y=0.01）についてはいずれの場合もLiNbO3以外の不純物相は確認されず、LiNbO3（PDF No.01-085-2456）の単相を形成していることが確認された。また、LixNbO3:Pr3+ y（[x=1.03, 1.05], y=0.01）については、不純物相としてLi3NbO4の結晶相が僅かながら確認された。 As can be seen from FIG. 4 (a), for Li x NbO 3 : Pr 3+ y ([x = 0.95, 0.97, 0.99, 1.00], y = 0.01), the impurity phase other than LiNbO 3 is It was not confirmed, but it was confirmed that a single phase of LiNbO 3 (PDF No.01-085-2456) was formed. As for Li x NbO 3 : Pr 3+ y ([x = 1.03, 1.05], y = 0.01), a slight crystal phase of Li 3 NbO 4 was confirmed as an impurity phase.
　次に、Ｘ線解析により得られたデータに基づき、リートベルト分析（Rietveld refinement）を行って格子定数の検討を行った。その結果を図４（ｂ）に示す。 Next, based on the data obtained by X-ray analysis, Rietveld analysis was performed to examine the lattice constant. The result is shown in FIG.
　図４（ｂ）において横軸はLixNbO3:Pr3+ yのxの値（0.95≦x≦1.05）、左縦軸は格子定数a、右縦軸は軸率c/aを示している。図４（ｂ）からも分かるように、xの値が異なることによる結晶構造上の違いが明らかとなった。 In FIG. 4B, the horizontal axis represents the value of x of Li x NbO 3 : Pr 3+ y (0.95 ≦ x ≦ 1.05), the left vertical axis represents the lattice constant a, and the right vertical axis represents the axial ratio c / a. Yes. As can be seen from FIG. 4B, the difference in crystal structure due to the difference in the value of x became clear.
　特に格子定数aにあっては、xの値が0.95や0.97では5.152を上回る比較的高値を示し、xの値が化学量論比である0.99から1.03までは5.151を下回る比較的低値を維持し、xの値が1.05となると再び増加傾向を示した。 In particular, for the lattice constant a, x values of 0.95 and 0.97 indicate relatively high values exceeding 5.152, and x values of 0.99 to 1.03, which are stoichiometric ratios, remain relatively low values below 5.151. When the value of x reached 1.05, it showed an increasing trend again.
　また軸率c/aにあっては、xの値が0.95から0.97では低下傾向を示したものの、0.97から0.99、1.00に至る過程で急激な増加傾向を示し、xの値が1.03、1.05において多少の揺らぎはあるものの比較的高値を維持する傾向が見られた。 In addition, in the axial ratio c / a, although the value of x showed a downward trend from 0.95 to 0.97, it showed a sharp increase in the process from 0.97 to 0.99 and 1.00, and the value of x was 1.03 and 1.05. Although there was some fluctuation, there was a tendency to maintain a relatively high price.
　次に、応力発光特性について評価を行った。先の〔２．LixNbO3:Pr3+ y（x=1, 0≦y≦0.1）の検討〕と同様、応力発光特性は、焼成試料と樹脂を混合し円柱形の樹脂ペレット（直径：2.5 cm、高さ：1.5 cm）を作成して応力発光体とし、応力発光評価システムにより評価した。測定方法は、樹脂ペレットに対し垂直方向の荷重を印加し、その時の発光強度をフォトンセンサで測定した。その結果を図５に示す。 Next, the stress luminescence characteristics were evaluated. The previous [2. Similar to Li x NbO 3 : Pr 3+ y (x = 1, 0 ≦ y ≦ 0.1)], the stress luminescence characteristics are a cylindrical resin pellet (diameter: 2.5 cm, high by mixing the fired sample and resin) The thickness was 1.5 cm) to obtain a stress luminescent material, which was evaluated by a stress luminescence evaluation system. The measuring method applied the load of the perpendicular direction with respect to the resin pellet, and measured the emitted light intensity at that time with the photon sensor. The result is shown in FIG.
　図５（ａ）は、LixNbO3:Pr3+ 0.01について、xの値を0.95≦x≦1.00の範囲内で変化させた際の各試料における荷重0～1000Nまでの応力発光曲線であり、図５（ｂ）は、LixNbO3:Pr3+ 0.01について、xの値を0.95≦x≦1.05の範囲内で変化させた際の各試料における荷重1000N時における発光強度を示したグラフである。 FIG. 5 (a) is a stress luminescence curve with a load of 0 to 1000N in each sample when the value of x is changed within the range of 0.95 ≦ x ≦ 1.00 for Li x NbO 3 : Pr 3+ 0.01 . FIG. 5B is a graph showing the light emission intensity at a load of 1000 N in each sample when the value of x is changed within the range of 0.95 ≦ x ≦ 1.05 for Li x NbO 3 : Pr 3+ 0.01. It is.
　図５（ａ）からも分かるように、xの値を0.95≦x≦1.00の範囲内としたものについては、いずれも発光が確認された。また、図５（ｂ）に示すように、特に、xの値が0.97を超えると著しく発光が増強され、化学量論比であるx+y=1.00(x=0.99)を超えてもなお、その発光強度の増強傾向は維持され、x=1.00において最大値が確認された。付言すれば、化学量論比であるLixNbO3:Pr3+ y（x=0.99,y=0.01）よりもリチウムの量を多く配合することで、極めて顕著な応力に対する応答性を示すことが確認された。 As can be seen from FIG. 5A, light emission was confirmed in all cases where the value of x was in the range of 0.95 ≦ x ≦ 1.00. Further, as shown in FIG. 5 (b), particularly when the value of x exceeds 0.97, the emission is remarkably enhanced, and even when the stoichiometric ratio x + y = 1.00 (x = 0.99) is exceeded, The tendency to increase the emission intensity was maintained, and the maximum value was confirmed at x = 1.00. In other words, by adding a larger amount of lithium than the stoichiometric ratio of Li x NbO 3 : Pr 3+ y (x = 0.99, y = 0.01), it should show extremely responsiveness to stress. Was confirmed.
　またここで、先に示した図４（ｂ）の結果を勘案すると、この発光強度の増強は、リチウム量xに由来する結晶構造の違いに基づくものと考えられ、格子定数aが5.151を下回り、且つ、軸率c/aが2.6900を上回る結晶構造を備えたLixNbO3:Pr3+ yを含む応力発光材料は、優れた応力応答性を有する応力発光材料として利用可能であるとも言える。 Here, considering the result shown in FIG. 4B, the enhancement of the emission intensity is considered to be based on the difference in the crystal structure derived from the lithium amount x, and the lattice constant a is less than 5.151. In addition, it can be said that the stress-stimulated luminescent material containing Li x NbO 3 : Pr 3+ y having a crystal structure with an axial ratio c / a exceeding 2.6900 can be used as a stress-stimulated luminescent material having excellent stress responsiveness. .
　次に、Li1.00NbO3:Pr3+ 0.01について、ひずみと発光強度との関係について検討を行った。具体的には、平均粒子径を大凡1μm程度としたLi1.00NbO3:Pr3+ 0.01の粉末をエポキシ樹脂に分散し、スプレー法により厚さ50μmの応力発光シート作成し、この応力発光シートを引張試験機に供することで、引張試験中に生起した応力発光特性の評価を行った。その結果を図６に示す。図６は、0～2000μstまでのひずみを付与した際の発光強度について５回の繰り返し試験を行った結果を示している。図６からも分かるように、0～2000μstのひずみに応じて極めて強い応力発光が確認された。特に、一部拡大図にて示すように、0～300μstの間においても優れた直線性を示し、0～100μstの間でも大凡1000[a.u.]もの発光強度が観察された。このことは、これまでの応力発光材料が、100μst以下のひずみに対し殆ど発光しないか、発光しても10[a.u.]以下程度の発光強度であったことを加味すると、飛躍的に強い発光であることが分かる。 Next, for Li 1.00 NbO 3 : Pr 3+ 0.01 , the relationship between strain and emission intensity was examined. Specifically, a powder of Li 1.00 NbO 3 : Pr 3+ 0.01 with an average particle diameter of about 1 μm is dispersed in an epoxy resin, and a stress light emitting sheet having a thickness of 50 μm is prepared by a spray method. By using the tensile tester, the stress luminescence characteristics generated during the tensile test were evaluated. The result is shown in FIG. FIG. 6 shows the results of repeating the test five times with respect to the emission intensity when a strain of 0 to 2000 μst is applied. As can be seen from FIG. 6, very strong stress luminescence was confirmed depending on the strain of 0 to 2000 μst. In particular, as shown in a partially enlarged view, excellent linearity was exhibited even between 0 and 300 μst, and emission intensity of approximately 1000 [au] was observed even between 0 and 100 μst. Considering that conventional stress light-emitting materials emit little light for strains of 100 μst or less, or that the light emission intensity is about 10 [au] or less, I understand that there is.
　すなわち、図６から分かるように、本実施形態に係る応力発光材料は、これまでにない超高感度を示し、また繰り返してひずみを加えた際に、超高感度な応力発光が再現性良く繰り返して示すことが確認された。特に、小ひずみ（0～300μst、特に0～100μst）の範囲内でも、LiNbO3:Pr3+塗膜の応力発光強度が歪みの増大に応じて、リニアに増大しており、LiNbO3:Pr3+を利用して小ひずみ高感度の応力発光を得ることが可能であるということが確認された。特に、応力発光シートのヤング率は数Gpa程度であることから、直径1μmの応力発光材料の微粒子にかかる力Ｆは、
　　F＝面積×応力＝μm×μm×ヤング率×ひずみ
であることに鑑みると、力ＦはpNレベルの力であるため、本実験結果から本実施形態に係る応力発光材料は、pNレベルの力を検知可能であることが分かる。 That is, as can be seen from FIG. 6, the stress-stimulated luminescent material according to this embodiment exhibits an unprecedented ultra-high sensitivity, and when repeated strain is applied, the ultra-sensitive stress luminescence is repeated with good reproducibility. It was confirmed that In particular, even within the range of small strain (0 to 300μst, especially 0 to 100μst), the stress emission intensity of LiNbO 3 : Pr 3+ coating increases linearly with increasing strain, and LiNbO 3 : Pr It was confirmed that it is possible to obtain stress emission with small strain and high sensitivity using 3+ . In particular, since the Young's modulus of the stress luminescent sheet is about several Gpa, the force F applied to the fine particles of the stress luminescent material having a diameter of 1 μm is:
Considering that F = area × stress = μm × μm × Young's modulus × strain, since the force F is a pN level force, the stress luminescent material according to the present embodiment has a pN level force based on the results of this experiment. It can be seen that it can be detected.
　また、Li0.99NbO3:Pr3+ 0.01について、図７の（ａ）に応力と発光との経時変化を示し、図７（ｂ）に相当応力と直線比例との関係を示す。 Further, with respect to Li 0.99 NbO 3 : Pr 3+ 0.01 , FIG. 7A shows changes with time in stress and luminescence, and FIG. 7B shows a relationship between equivalent stress and linear proportion.
　図７（ａ）から、応力発光強度は荷重と共に増大することが分かる。 FIG. 7 (a) shows that the stress emission intensity increases with the load.
　また、図７（ｂ）から、相当応力分布の計算結果とよく一致しており、定量的な解析に有用であることが分かる。 Also, from FIG. 7 (b), it is in good agreement with the calculation result of the equivalent stress distribution, and it can be seen that it is useful for quantitative analysis.
〔４．LixNbO3:Pr3+ y（1.00≦x≦2.4, y=0.01）の検討〕
　前述の〔１．応力発光材料の調製〕に従い、LixNbO3:Pr3+ y（1.00≦x≦2.4, y=0.01）の調製を行った。調製した試料は粉末X線回折装置により結晶相の同定を行った。その結果を図８に示す。 [4. Li x NbO 3 : Pr 3+ y (1.00 ≦ x ≦ 2.4, y = 0.01)
[1. Preparation of Stress Luminescent Material] Li x NbO 3 : Pr 3+ y (1.00 ≦ x ≦ 2.4, y = 0.01) was prepared. The prepared sample was identified by a powder X-ray diffractometer. The result is shown in FIG.
　図８に示すように、LixNbO3:Pr3+ y（x=1.0, y=0.01）のときは、LiNbO3以外の不純物相は確認されなかったが、LixNbO3:Pr3+ y（[x=1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4], y=0.01）においては、Liの割合が高まるに従い、Li3NbO4の結晶相が徐々に増加するのが確認された。 As shown in FIG. 8, when Li x NbO 3 : Pr 3+ y (x = 1.0, y = 0.01), no impurity phase other than LiNbO 3 was confirmed, but Li x NbO 3 : Pr 3+ In y ([x = 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4], y = 0.01), it was confirmed that the Li 3 NbO 4 crystal phase gradually increased as the Li content increased. It was.
　次に、応力発光特性について評価を行った。先の〔２．LixNbO3:Pr3+ y（x=1, 0≦y≦0.1）の検討〕と同様、応力発光特性は、焼成試料と樹脂を混合し円柱形の樹脂ペレット（直径：2.5 cm、高さ：1.5 cm）を作成して応力発光体とし、応力発光評価システムにより評価した。測定方法は、樹脂ペレットに対し垂直方向の荷重を印加し、その時の発光強度をフォトンセンサで測定した。その結果を図９に示す。 Next, the stress luminescence characteristics were evaluated. The previous [2. Similar to Li x NbO 3 : Pr 3+ y (x = 1, 0 ≦ y ≦ 0.1)], the stress luminescence characteristics are a cylindrical resin pellet (diameter: 2.5 cm, high by mixing the fired sample and resin) The thickness was 1.5 cm) to obtain a stress luminescent material, which was evaluated by a stress luminescence evaluation system. The measuring method applied the load of the perpendicular direction with respect to the resin pellet, and measured the emitted light intensity at that time with the photon sensor. The result is shown in FIG.
　図９（ａ）～（ｅ）は、LixNbO3:Pr3+ 0.01について、xの値を1.0, 1.2, 1.4, 1.6, 1.8, 2.4に変化させた際の各試料における荷重0～1000Nまでの応力発光の経時変化を示したグラフである。 9 (a) to 9 (e) show the load 0 to 1000N for each sample when the value of x is changed to 1.0, 1.2, 1.4, 1.6, 1.8, 2.4 for Li x NbO 3 : Pr 3+ 0.01. It is the graph which showed the time-dependent change of stress luminescence until.
　図９に示すように、三角波状に最大1000Nの荷重を２連続で付与した際、x=1.0において１回目の1000N荷重時に980[a.u.]の最大発光が確認されたのを初め、x=1.2では7238[a.u.]、x=1.4では7796[a.u.]、x=1.6では9680[a.u.]、x=1.8では10481[a.u.]と徐々に増強傾向が認められた。 As shown in FIG. 9, when a maximum load of 1000 N was applied in a triangular wave shape continuously, the maximum emission of 980 [au] was confirmed at the first load of 1000 N at x = 1.0. In 7238 [au], x = 1.4, 7796 [au], x = 1.6, 9680 [au], and x = 1.8, 10481 [au].
　また、更にリチウム割合を高め、x=2.4とした際には、1929と発光強度の低下が認められた。しかしながら、このような発光強度であっても、圧電体を母体材料とする従来の応力発光材料では実現できなかった発光強度である。 Further, when the lithium ratio was further increased and x = 2.4, the emission intensity decreased to 1929. However, even with such a light emission intensity, it is a light emission intensity that could not be realized by a conventional stress light-emitting material using a piezoelectric material as a base material.
　なお、図８において示したように、LixNbO3:Pr3+ y（[x=1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4], y=0.01）においては、Li3NbO4の結晶相が不純物相として生成しているが、このLi3NbO4の結晶相は応力発光に寄与するものではなく、LixNbO3:Pr3+ y（[x=1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4], y=0.01）の結晶単独で応力応答が完結していることが本発明者らの研究により明らかとなっている。 In addition, as shown in FIG. 8, in Li x NbO 3 : Pr 3+ y ([x = 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4], y = 0.01), Li 3 NbO 4 Although the crystal phase is formed as an impurity phase, this crystal phase of Li 3 NbO 4 does not contribute to stress luminescence, and Li x NbO 3 : Pr 3+ y ([x = 1.2, 1.4, 1.6, 1.8 , 2.0, 2.2, 2.4], y = 0.01), it has been clarified by the present inventors that the stress response is completed by the crystal alone.
　また、着目すべきは、本実施形態に係る応力発光材料は不純物相を有している状態であっても、応力に応じた十分な発光が得られていることである。この点からも不純物相は応力発光に寄与もしないし、応力発光が実用不可能になる程度にまで阻害することもないことが分かる。 Also, it should be noted that the stress-stimulated luminescent material according to the present embodiment can obtain sufficient light emission according to the stress even in a state having an impurity phase. Also from this point, it can be seen that the impurity phase does not contribute to the stress luminescence and does not inhibit the stress luminescence to such an extent that it becomes impractical.
〔５．Pr3+以外の金属イオンによる応力発光の検討〕
　次に、上述してきたPr3+以外の金属イオンをドープした際の応力発光について検討を行った。具体的には、Li1.00NbO3:Eu3+ 0.01、Li1.00NbO3:Er3+ 0.01、Li1.00NbO3:Nd3+ 0.01について、先の〔２．LixNbO3:Pr3+ y（x=1, 0≦y≦0.1）の検討〕と同様、焼成試料と樹脂を混合し円柱形の樹脂ペレット（直径：2.5 cm、高さ：1.5 cm）を作成して応力発光体とし、応力発光評価システムにより評価した。測定方法は、樹脂ペレットに対し垂直方向の荷重(1000N)を印加し、その時の発光強度をフォトンセンサで測定した。その結果を図１０に示す。 [5. (Study of stress luminescence by metal ions other than Pr 3+ )
Next, stress luminescence was examined when doping metal ions other than Pr 3+ described above. Specifically, for Li 1.00 NbO 3 : Eu 3+ 0.01 , Li 1.00 NbO 3 : Er 3+ 0.01 , and Li 1.00 NbO 3 : Nd 3+ 0.01 , [2. As in Li x NbO 3 : Pr 3+ y (x = 1, 0 ≦ y ≦ 0.1)], a cylindrical resin pellet (diameter: 2.5 cm, height: 1.5 cm) mixed with a calcined sample and resin Was made into a stress luminescent material and evaluated by a stress luminescence evaluation system. In the measurement method, a vertical load (1000 N) was applied to the resin pellet, and the light emission intensity at that time was measured with a photon sensor. The result is shown in FIG.
　図１０からも分かるように、Li1.00NbO3:Eu3+ 0.01、Li1.00NbO3:Er3+ 0.01、Li1.00NbO3:Nd3+ 0.01のいずれにおいても、応力発光が検出された。 As can be seen from FIG. 10, stress luminescence was detected in any of Li 1.00 NbO 3 : Eu 3+ 0.01 , Li 1.00 NbO 3 : Er 3+ 0.01 , and Li 1.00 NbO 3 : Nd 3+ 0.01 .
〔６．応力発光材料の使用例について〕
　これまで述べてきたように、本実施形態に係る応力発光材料は、極めて小さな応力やひずみに応答して発光を示すものであり、特に、100μst以下の微小ひずみに対しても発光を示す点が特徴的であると言える。 [6. Example of use of stress luminescent material)
As described so far, the stress-stimulated luminescent material according to the present embodiment emits light in response to extremely small stress or strain, and in particular, it exhibits light emission even for a minute strain of 100 μst or less. It can be said that it is characteristic.
　このような本実施形態に係る応力発光材料は、例えば、微小ひずみに対する応力の高感度測定に応用することが可能である。 Such a stress-stimulated luminescent material according to this embodiment can be applied to, for example, highly sensitive measurement of stress against minute strain.
　また、数十μstのひずみがあれば発光は可能であることから、例えばナノマシンの車軸などのような構成部材の応力を計測したり、細胞内に働く応力の変化を光により可視化することなども考えられる。 In addition, since light emission is possible if there is a strain of several tens of μst, it is possible to measure the stress of components such as the nanomachine axle, and to visualize changes in stress acting on cells with light, etc. Conceivable.
　すなわち、ナノマシン等において数十μstのひずみを生じさせる力は大凡1～1000pN程度の力（pNオーダーの力）であると考えられ、応力計測を行うナノマシンの構成部材に本実施形態に係る応力発光材料を配置すれば、同応力発光材料は数十μstのひずみに対しても応答可能であるため、ひずみにより発光が得られることとなる。このことは、先の図６にて示した結果からも明らかであり、本実施形態に係る応力発光材料は、pNオーダーの力を検出できるものであると言える。 That is, it is considered that the force that generates a strain of several tens of μst in a nanomachine or the like is a force of about 1 to 1000 pN (pN order force). If the material is arranged, the light emission material with the same stress can respond to a strain of several tens of μst, so that light emission can be obtained by the strain. This is also clear from the results shown in FIG. 6, and it can be said that the stress-stimulated luminescent material according to this embodiment can detect a pN-order force.
　また、例えば筋肉細胞など伸縮するような細胞内や細胞外に本実施形態に係る応力発光材料を配置すれば、細胞の伸縮動作に応じた発光により、細胞内外における応力や運動の経時変化を光により観測したり、その強度により応力や運動の強さを知ることも可能となる。これまでに細胞内外の所定物質の分布などは光により検出が行われていたが、細胞内外に加わる力や運動を可視化するといった例はなく、極めて画期的であると言える。すなわち、本実施形態に係る応力発光材料は、応力や分子運動、自然振動による微小な力でも高感度で発光が可能な、圧電体を母体材料とした単相の応力発光材料としての利用可能性を有している。 In addition, if the stress-stimulated luminescent material according to the present embodiment is placed inside or outside a cell that stretches or contracts, for example, muscle cells, the time-dependent changes in stress and movement inside and outside the cell are emitted by light emission according to the stretching and contracting operation of the cell. It is also possible to observe the strength of the stress and movement by the intensity of the observation. Until now, the distribution of the predetermined substance inside and outside the cell has been detected by light, but there is no example of visualizing the force and movement applied inside and outside the cell, and it can be said that it is extremely innovative. That is, the stress-stimulated luminescent material according to this embodiment can be used as a single-phase stress-stimulated luminescent material using a piezoelectric material as a base material, which can emit light with high sensitivity even with a minute force due to stress, molecular motion, or natural vibration. have.
　上述してきたように、本実施形態に係る応力発光材料によれば、LiNbO3の結晶体を構成する一部のLiを、希土類金属イオン及び遷移金属イオンから選ばれる少なくとも１種の金属イオンにより置換して構成したため、微小な応力に対しても高感度で発光が可能な、圧電体を母体材料とする単相の応力発光材料を提供することができる。 As described above, according to the stress-stimulated luminescent material according to this embodiment, a part of Li constituting the crystal of LiNbO 3 is replaced with at least one metal ion selected from rare earth metal ions and transition metal ions. Therefore, it is possible to provide a single-phase stress luminescent material using a piezoelectric material as a base material, which can emit light with high sensitivity even for a minute stress.
　最後に、上述した各実施の形態の説明は本発明の一例であり、本発明は上述の実施の形態に限定されることはない。このため、上述した各実施の形態以外であっても、本発明に係る技術的思想を逸脱しない範囲であれば、設計等に応じて種々の変更が可能であることは勿論である。 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 (9)

  1. 　LiNbO3の結晶体を構成する一部のLiが、希土類金属イオン及び遷移金属イオンから選ばれる少なくとも１種の金属イオンにより置換された応力発光材料。 A stress-stimulated luminescent material in which a part of Li constituting a LiNbO 3 crystal is substituted with at least one metal ion selected from rare earth metal ions and transition metal ions.
  2. 　一般式LixNbO3:My（ただし、Mは、LiNbO3の結晶体を構成する一部のLiを置換する希土類金属イオン及び遷移金属イオンから選ばれる少なくとも１種の金属イオン。）で表される非化学量論的組成を有し、x=1-yであって、0.0001≦y≦0.2であることを特徴とする請求項１に記載の応力発光材料。 Represented by the general formula Li x NbO 3 : M y (where M is at least one metal ion selected from rare earth metal ions and transition metal ions substituting for part of Li constituting the crystal of LiNbO 3 ). The stress-stimulated luminescent material according to claim 1, wherein x = 1−y and 0.0001 ≦ y ≦ 0.2.
  3. 　一般式LixNbO3:My（ただし、Mは、LiNbO3の結晶体を構成する一部のLiを置換する希土類金属イオン及び遷移金属イオンから選ばれる少なくとも１種の金属イオン。）で表される非化学量論的組成を有し、x＞1-yであって、0.0001≦y≦0.2であることを特徴とする請求項１に記載の応力発光材料。 Represented by the general formula Li x NbO 3 : M y (where M is at least one metal ion selected from rare earth metal ions and transition metal ions substituting for part of Li constituting the crystal of LiNbO 3 ). The stress-stimulated luminescent material according to claim 1, wherein x> 1-y and 0.0001 ≦ y ≦ 0.2.
  4. 　0.8＜x≦3.0であることを特徴とする請求項３に記載の応力発光材料。 The stress-stimulated luminescent material according to claim 3, wherein 0.8 <x ≦ 3.0.
  5. 　前記金属イオンは、Pr3+であることを特徴とする請求項１～４いずれか１項に記載の応力発光材料。 The stress-stimulated luminescent material according to any one of claims 1 to 4, wherein the metal ion is Pr 3+ .
  6. 　請求項１～５いずれか１項に記載の応力発光材料が所定のマトリクス材料中に分散された応力発光体。 A stress-stimulated luminescent material in which the stress-stimulated luminescent material according to any one of claims 1 to 5 is dispersed in a predetermined matrix material.
  7. 　1000pN以下の力を発光により検出するための請求項１～５いずれか１項に記載の応力発光材料の使用。 Use of the stress-stimulated luminescent material according to any one of claims 1 to 5 for detecting a force of 1000 pN or less by luminescence.
  8. 　100μst以下の微小ひずみを発光により検知するための請求項１～５いずれか１項に記載の応力発光材料の使用。 Use of the stress-stimulated luminescent material according to any one of claims 1 to 5 for detecting minute strains of 100 µst or less by luminescence.
  9. 　ニオブ化合物と、リチウム化合物と、希土類金属及び遷移金属から選ばれる少なくとも１種の金属の化合物とを混合して焼成するLiNbO3を母体材料とした応力発光材料の製造方法であって、ニオブ原子とリチウム原子とのモル比を１：0.8～3.0とすることを特徴とする応力発光材料の製造方法。 A method for producing a stress-stimulated luminescent material using LiNbO 3 as a base material obtained by mixing and firing a niobium compound, a lithium compound, and a compound of at least one metal selected from rare earth metals and transition metals, A method for producing a stress-stimulated luminescent material, wherein the molar ratio to lithium atoms is 1: 0.8 to 3.0.
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